7 :abbr:`BGP` stands for Border Gateway Protocol. The latest BGP version is 4.
8 BGP-4 is one of the Exterior Gateway Protocols and the de facto standard
9 interdomain routing protocol. BGP-4 is described in :rfc:`1771` and updated by
10 :rfc:`4271`. :rfc:`2858` adds multiprotocol support to BGP-4.
17 The default configuration file of *bgpd* is :file:`bgpd.conf`. *bgpd* searches
18 the current directory first, followed by |INSTALL_PREFIX_ETC|/bgpd.conf. All of
19 *bgpd*'s commands must be configured in :file:`bgpd.conf` when the integrated
20 config is not being used.
22 *bgpd* specific invocation options are described below. Common options may also
23 be specified (:ref:`common-invocation-options`).
27 .. option:: -p, --bgp_port <port>
29 Set the bgp protocol's port number. When port number is 0, that means do not
32 .. option:: -l, --listenon
34 Specify a specific IP address for bgpd to listen on, rather than its default
35 of ``0.0.0.0`` / ``::``. This can be useful to constrain bgpd to an internal
36 address, or to run multiple bgpd processes on one host.
38 .. option:: -n, --no_kernel
40 Do not install learned routes into the linux kernel. This option is useful
41 for a route-reflector environment or if you are running multiple bgp
42 processes in the same namespace. This option is different than the --no_zebra
43 option in that a ZAPI connection is made.
45 .. option:: -S, --skip_runas
47 Skip the normal process of checking capabilities and changing user and group
50 .. option:: -e, --ecmp
52 Run BGP with a limited ecmp capability, that is different than what BGP
53 was compiled with. The value specified must be greater than 0 and less
54 than or equal to the MULTIPATH_NUM specified on compilation.
56 .. option:: -Z, --no_zebra
58 Do not communicate with zebra at all. This is different than the --no_kernel
59 option in that we do not even open a ZAPI connection to the zebra process.
61 .. option:: -s, --socket_size
63 When opening tcp connections to our peers, set the socket send buffer
64 size that the kernel will use for the peers socket. This option
65 is only really useful at a very large scale. Experimentation should
66 be done to see if this is helping or not at the scale you are running
72 .. option:: -I, --int_num
74 Set zclient id. This is required when using Zebra label manager in proxy mode.
76 .. _bgp-basic-concepts:
81 .. _bgp-autonomous-systems:
88 An AS is a connected group of one or more IP prefixes run by one or more
89 network operators which has a SINGLE and CLEARLY DEFINED routing policy.
91 Each AS has an identifying number associated with it called an :abbr:`ASN
92 (Autonomous System Number)`. This is a two octet value ranging in value from 1
93 to 65535. The AS numbers 64512 through 65535 are defined as private AS numbers.
94 Private AS numbers must not be advertised on the global Internet.
96 The :abbr:`ASN (Autonomous System Number)` is one of the essential elements of
97 BGP. BGP is a distance vector routing protocol, and the AS-Path framework
98 provides distance vector metric and loop detection to BGP.
100 .. seealso:: :rfc:`1930`
102 .. _bgp-address-families:
107 Multiprotocol extensions enable BGP to carry routing information for multiple
108 network layer protocols. BGP supports an Address Family Identifier (AFI) for
109 IPv4 and IPv6. Support is also provided for multiple sets of per-AFI
110 information via the BGP Subsequent Address Family Identifier (SAFI). FRR
111 supports SAFIs for unicast information, labeled information (:rfc:`3107` and
112 :rfc:`8277`), and Layer 3 VPN information (:rfc:`4364` and :rfc:`4659`).
114 .. _bgp-route-selection:
119 The route selection process used by FRR's BGP implementation uses the following
120 decision criterion, starting at the top of the list and going towards the
121 bottom until one of the factors can be used.
125 Prefer higher local weight routes to lower routes.
127 2. **Local preference check**
129 Prefer higher local preference routes to lower.
131 3. **Local route check**
133 Prefer local routes (statics, aggregates, redistributed) to received routes.
135 4. **AS path length check**
137 Prefer shortest hop-count AS_PATHs.
141 Prefer the lowest origin type route. That is, prefer IGP origin routes to
142 EGP, to Incomplete routes.
146 Where routes with a MED were received from the same AS, prefer the route
147 with the lowest MED. :ref:`bgp-med`.
149 7. **External check**
151 Prefer the route received from an external, eBGP peer over routes received
152 from other types of peers.
154 8. **IGP cost check**
156 Prefer the route with the lower IGP cost.
158 9. **Multi-path check**
160 If multi-pathing is enabled, then check whether the routes not yet
161 distinguished in preference may be considered equal. If
162 :clicmd:`bgp bestpath as-path multipath-relax` is set, all such routes are
163 considered equal, otherwise routes received via iBGP with identical AS_PATHs
164 or routes received from eBGP neighbours in the same AS are considered equal.
166 10. **Already-selected external check**
168 Where both routes were received from eBGP peers, then prefer the route
169 which is already selected. Note that this check is not applied if
170 :clicmd:`bgp bestpath compare-routerid` is configured. This check can
171 prevent some cases of oscillation.
173 11. **Router-ID check**
175 Prefer the route with the lowest `router-ID`. If the route has an
176 `ORIGINATOR_ID` attribute, through iBGP reflection, then that router ID is
177 used, otherwise the `router-ID` of the peer the route was received from is
180 12. **Cluster-List length check**
182 The route with the shortest cluster-list length is used. The cluster-list
183 reflects the iBGP reflection path the route has taken.
187 Prefer the route received from the peer with the higher transport layer
188 address, as a last-resort tie-breaker.
190 .. _bgp-capability-negotiation:
192 Capability Negotiation
193 ----------------------
195 When adding IPv6 routing information exchange feature to BGP. There were some
196 proposals. :abbr:`IETF (Internet Engineering Task Force)`
197 :abbr:`IDR (Inter Domain Routing)` adopted a proposal called Multiprotocol
198 Extension for BGP. The specification is described in :rfc:`2283`. The protocol
199 does not define new protocols. It defines new attributes to existing BGP. When
200 it is used exchanging IPv6 routing information it is called BGP-4+. When it is
201 used for exchanging multicast routing information it is called MBGP.
203 *bgpd* supports Multiprotocol Extension for BGP. So if a remote peer supports
204 the protocol, *bgpd* can exchange IPv6 and/or multicast routing information.
206 Traditional BGP did not have the feature to detect a remote peer's
207 capabilities, e.g. whether it can handle prefix types other than IPv4 unicast
208 routes. This was a big problem using Multiprotocol Extension for BGP in an
209 operational network. :rfc:`2842` adopted a feature called Capability
210 Negotiation. *bgpd* use this Capability Negotiation to detect the remote peer's
211 capabilities. If a peer is only configured as an IPv4 unicast neighbor, *bgpd*
212 does not send these Capability Negotiation packets (at least not unless other
213 optional BGP features require capability negotiation).
215 By default, FRR will bring up peering with minimal common capability for the
216 both sides. For example, if the local router has unicast and multicast
217 capabilities and the remote router only has unicast capability the local router
218 will establish the connection with unicast only capability. When there are no
219 common capabilities, FRR sends Unsupported Capability error and then resets the
222 .. _bgp-router-configuration:
224 BGP Router Configuration
225 ========================
230 First of all you must configure BGP router with the :clicmd:`router bgp ASN`
231 command. The AS number is an identifier for the autonomous system. The BGP
232 protocol uses the AS number for detecting whether the BGP connection is
233 internal or external.
235 .. index:: router bgp ASN
236 .. clicmd:: router bgp ASN
238 Enable a BGP protocol process with the specified ASN. After
239 this statement you can input any `BGP Commands`.
241 .. index:: no router bgp ASN
242 .. clicmd:: no router bgp ASN
244 Destroy a BGP protocol process with the specified ASN.
246 .. index:: bgp router-id A.B.C.D
247 .. clicmd:: bgp router-id A.B.C.D
249 This command specifies the router-ID. If *bgpd* connects to *zebra* it gets
250 interface and address information. In that case default router ID value is
251 selected as the largest IP Address of the interfaces. When `router zebra` is
252 not enabled *bgpd* can't get interface information so `router-id` is set to
253 0.0.0.0. So please set router-id by hand.
256 .. _bgp-multiple-autonomous-systems:
258 Multiple Autonomous Systems
259 ---------------------------
261 FRR's BGP implementation is capable of running multiple autonomous systems at
262 once. Each configured AS corresponds to a :ref:`zebra-vrf`. In the past, to get
263 the same functionality the network administrator had to run a new *bgpd*
264 process; using VRFs allows multiple autonomous systems to be handled in a
267 When using multiple autonomous systems, all router config blocks after the
268 first one must specify a VRF to be the target of BGP's route selection. This
269 VRF must be unique within respect to all other VRFs being used for the same
270 purpose, i.e. two different autonomous systems cannot use the same VRF.
271 However, the same AS can be used with different VRFs.
275 The separated nature of VRFs makes it possible to peer a single *bgpd*
276 process to itself, on one machine. Note that this can be done fully within
277 BGP without a corresponding VRF in the kernel or Zebra, which enables some
278 practical use cases such as :ref:`route reflectors <bgp-route-reflector>`
281 Configuration of additional autonomous systems, or of a router that targets a
282 specific VRF, is accomplished with the following command:
284 .. index:: router bgp ASN vrf VRFNAME
285 .. clicmd:: router bgp ASN vrf VRFNAME
287 ``VRFNAME`` is matched against VRFs configured in the kernel. When ``vrf
288 VRFNAME`` is not specified, the BGP protocol process belongs to the default
291 An example configuration with multiple autonomous systems might look like this:
296 neighbor 10.0.0.1 remote-as 20
297 neighbor 10.0.0.2 remote-as 30
299 router bgp 2 vrf blue
300 neighbor 10.0.0.3 remote-as 40
301 neighbor 10.0.0.4 remote-as 50
304 neighbor 10.0.0.5 remote-as 60
305 neighbor 10.0.0.6 remote-as 70
308 .. seealso:: :ref:`bgp-vrf-route-leaking`
309 .. seealso:: :ref:`zebra-vrf`
317 In addition to supporting multiple autonomous systems, FRR's BGP implementation
318 also supports *views*.
320 BGP views are almost the same as normal BGP processes, except that routes
321 selected by BGP are not installed into the kernel routing table. Each BGP view
322 provides an independent set of routing information which is only distributed
323 via BGP. Multiple views can be supported, and BGP view information is always
324 independent from other routing protocols and Zebra/kernel routes. BGP views use
325 the core instance (i.e., default VRF) for communication with peers.
327 .. index:: router bgp AS-NUMBER view NAME
328 .. clicmd:: router bgp AS-NUMBER view NAME
330 Make a new BGP view. You can use an arbitrary word for the ``NAME``. Routes
331 selected by the view are not installed into the kernel routing table.
333 With this command, you can setup Route Server like below.
339 neighbor 10.0.0.1 remote-as 2
340 neighbor 10.0.0.2 remote-as 3
343 neighbor 10.0.0.3 remote-as 4
344 neighbor 10.0.0.4 remote-as 5
346 .. index:: show [ip] bgp view NAME
347 .. clicmd:: show [ip] bgp view NAME
349 Display the routing table of BGP view ``NAME``.
355 .. index:: bgp bestpath as-path confed
356 .. clicmd:: bgp bestpath as-path confed
358 This command specifies that the length of confederation path sets and
359 sequences should should be taken into account during the BGP best path
362 .. index:: bgp bestpath as-path multipath-relax
363 .. clicmd:: bgp bestpath as-path multipath-relax
365 This command specifies that BGP decision process should consider paths
366 of equal AS_PATH length candidates for multipath computation. Without
367 the knob, the entire AS_PATH must match for multipath computation.
369 .. clicmd:: bgp bestpath compare-routerid
371 Ensure that when comparing routes where both are equal on most metrics,
372 including local-pref, AS_PATH length, IGP cost, MED, that the tie is broken
375 If this option is enabled, then the already-selected check, where
376 already selected eBGP routes are preferred, is skipped.
378 If a route has an `ORIGINATOR_ID` attribute because it has been reflected,
379 that `ORIGINATOR_ID` will be used. Otherwise, the router-ID of the peer the
380 route was received from will be used.
382 The advantage of this is that the route-selection (at this point) will be
383 more deterministic. The disadvantage is that a few or even one lowest-ID
384 router may attract all traffic to otherwise-equal paths because of this
385 check. It may increase the possibility of MED or IGP oscillation, unless
386 other measures were taken to avoid these. The exact behaviour will be
387 sensitive to the iBGP and reflection topology.
391 Administrative Distance Metrics
392 -------------------------------
394 .. index:: distance bgp (1-255) (1-255) (1-255)
395 .. clicmd:: distance bgp (1-255) (1-255) (1-255)
397 This command change distance value of BGP. The arguments are the distance
398 values for for external routes, internal routes and local routes
401 .. index:: distance (1-255) A.B.C.D/M
402 .. clicmd:: distance (1-255) A.B.C.D/M
404 .. index:: distance (1-255) A.B.C.D/M WORD
405 .. clicmd:: distance (1-255) A.B.C.D/M WORD
407 Sets the administrative distance for a particular route.
409 .. _bgp-requires-policy:
411 Require policy on EBGP
412 -------------------------------
414 .. index:: [no] bgp ebgp-requires-policy
415 .. clicmd:: [no] bgp ebgp-requires-policy
417 This command requires incoming and outgoing filters to be applied
418 for eBGP sessions. Without the incoming filter, no routes will be
419 accepted. Without the outgoing filter, no routes will be announced.
421 This is enabled by default.
423 When the incoming or outgoing filter is missing you will see
424 "(Policy)" sign under ``show bgp summary``:
428 exit1# show bgp summary
430 IPv4 Unicast Summary:
431 BGP router identifier 10.10.10.1, local AS number 65001 vrf-id 0
433 RIB entries 7, using 1344 bytes of memory
434 Peers 2, using 43 KiB of memory
436 Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd PfxSnt
437 192.168.0.2 4 65002 8 10 0 0 0 00:03:09 5 (Policy)
438 fe80:1::2222 4 65002 9 11 0 0 0 00:03:09 (Policy) (Policy)
440 Reject routes with AS_SET or AS_CONFED_SET types
441 ------------------------------------------------
443 .. index:: [no] bgp reject-as-sets
444 .. clicmd:: [no] bgp reject-as-sets
446 This command enables rejection of incoming and outgoing routes having AS_SET or AS_CONFED_SET type.
448 Disable checking if nexthop is connected on EBGP sessions
449 ---------------------------------------------------------
451 .. index:: [no] bgp disable-ebgp-connected-route-check
452 .. clicmd:: [no] bgp disable-ebgp-connected-route-check
454 This command is used to disable the connection verification process for EBGP peering sessions
455 that are reachable by a single hop but are configured on a loopback interface or otherwise
456 configured with a non-directly connected IP address.
458 .. _bgp-route-flap-dampening:
463 .. clicmd:: bgp dampening (1-45) (1-20000) (1-20000) (1-255)
465 This command enables BGP route-flap dampening and specifies dampening parameters.
468 Half-life time for the penalty
471 Value to start reusing a route
474 Value to start suppressing a route
477 Maximum duration to suppress a stable route
479 The route-flap damping algorithm is compatible with :rfc:`2439`. The use of
480 this command is not recommended nowadays.
482 At the moment, route-flap dampening is not working per VRF and is working only
483 for IPv4 unicast and multicast.
486 https://www.ripe.net/publications/docs/ripe-378
490 Multi-Exit Discriminator
491 ------------------------
493 The BGP :abbr:`MED (Multi-Exit Discriminator)` attribute has properties which
494 can cause subtle convergence problems in BGP. These properties and problems
495 have proven to be hard to understand, at least historically, and may still not
496 be widely understood. The following attempts to collect together and present
497 what is known about MED, to help operators and FRR users in designing and
498 configuring their networks.
500 The BGP :abbr:`MED` attribute is intended to allow one AS to indicate its
501 preferences for its ingress points to another AS. The MED attribute will not be
502 propagated on to another AS by the receiving AS - it is 'non-transitive' in the
505 E.g., if AS X and AS Y have 2 different BGP peering points, then AS X might set
506 a MED of 100 on routes advertised at one and a MED of 200 at the other. When AS
507 Y selects between otherwise equal routes to or via AS X, AS Y should prefer to
508 take the path via the lower MED peering of 100 with AS X. Setting the MED
509 allows an AS to influence the routing taken to it within another, neighbouring
512 In this use of MED it is not really meaningful to compare the MED value on
513 routes where the next AS on the paths differs. E.g., if AS Y also had a route
514 for some destination via AS Z in addition to the routes from AS X, and AS Z had
515 also set a MED, it wouldn't make sense for AS Y to compare AS Z's MED values to
516 those of AS X. The MED values have been set by different administrators, with
517 different frames of reference.
519 The default behaviour of BGP therefore is to not compare MED values across
520 routes received from different neighbouring ASes. In FRR this is done by
521 comparing the neighbouring, left-most AS in the received AS_PATHs of the routes
522 and only comparing MED if those are the same.
524 Unfortunately, this behaviour of MED, of sometimes being compared across routes
525 and sometimes not, depending on the properties of those other routes, means MED
526 can cause the order of preference over all the routes to be undefined. That is,
527 given routes A, B, and C, if A is preferred to B, and B is preferred to C, then
528 a well-defined order should mean the preference is transitive (in the sense of
529 orders [#med-transitivity-rant]_) and that A would be preferred to C.
531 However, when MED is involved this need not be the case. With MED it is
532 possible that C is actually preferred over A. So A is preferred to B, B is
533 preferred to C, but C is preferred to A. This can be true even where BGP
534 defines a deterministic 'most preferred' route out of the full set of A,B,C.
535 With MED, for any given set of routes there may be a deterministically
536 preferred route, but there need not be any way to arrange them into any order
537 of preference. With unmodified MED, the order of preference of routes literally
540 That MED can induce non-transitive preferences over routes can cause issues.
541 Firstly, it may be perceived to cause routing table churn locally at speakers;
542 secondly, and more seriously, it may cause routing instability in iBGP
543 topologies, where sets of speakers continually oscillate between different
546 The first issue arises from how speakers often implement routing decisions.
547 Though BGP defines a selection process that will deterministically select the
548 same route as best at any given speaker, even with MED, that process requires
549 evaluating all routes together. For performance and ease of implementation
550 reasons, many implementations evaluate route preferences in a pair-wise fashion
551 instead. Given there is no well-defined order when MED is involved, the best
552 route that will be chosen becomes subject to implementation details, such as
553 the order the routes are stored in. That may be (locally) non-deterministic,
554 e.g.: it may be the order the routes were received in.
556 This indeterminism may be considered undesirable, though it need not cause
557 problems. It may mean additional routing churn is perceived, as sometimes more
558 updates may be produced than at other times in reaction to some event .
560 This first issue can be fixed with a more deterministic route selection that
561 ensures routes are ordered by the neighbouring AS during selection.
562 :clicmd:`bgp deterministic-med`. This may reduce the number of updates as routes
563 are received, and may in some cases reduce routing churn. Though, it could
564 equally deterministically produce the largest possible set of updates in
565 response to the most common sequence of received updates.
567 A deterministic order of evaluation tends to imply an additional overhead of
568 sorting over any set of n routes to a destination. The implementation of
569 deterministic MED in FRR scales significantly worse than most sorting
570 algorithms at present, with the number of paths to a given destination. That
571 number is often low enough to not cause any issues, but where there are many
572 paths, the deterministic comparison may quickly become increasingly expensive
575 Deterministic local evaluation can *not* fix the second, more major, issue of
576 MED however. Which is that the non-transitive preference of routes MED can
577 cause may lead to routing instability or oscillation across multiple speakers
578 in iBGP topologies. This can occur with full-mesh iBGP, but is particularly
579 problematic in non-full-mesh iBGP topologies that further reduce the routing
580 information known to each speaker. This has primarily been documented with iBGP
581 :ref:`route-reflection <bgp-route-reflector>` topologies. However, any
582 route-hiding technologies potentially could also exacerbate oscillation with MED.
584 This second issue occurs where speakers each have only a subset of routes, and
585 there are cycles in the preferences between different combinations of routes -
586 as the undefined order of preference of MED allows - and the routes are
587 distributed in a way that causes the BGP speakers to 'chase' those cycles. This
588 can occur even if all speakers use a deterministic order of evaluation in route
591 E.g., speaker 4 in AS A might receive a route from speaker 2 in AS X, and from
592 speaker 3 in AS Y; while speaker 5 in AS A might receive that route from
593 speaker 1 in AS Y. AS Y might set a MED of 200 at speaker 1, and 100 at speaker
594 3. I.e, using ASN:ID:MED to label the speakers:
600 X:2------|--A:4-------A:5--|-Y:1:200
606 Assuming all other metrics are equal (AS_PATH, ORIGIN, 0 IGP costs), then based
607 on the RFC4271 decision process speaker 4 will choose X:2 over Y:3:100, based
608 on the lower ID of 2. Speaker 4 advertises X:2 to speaker 5. Speaker 5 will
609 continue to prefer Y:1:200 based on the ID, and advertise this to speaker 4.
610 Speaker 4 will now have the full set of routes, and the Y:1:200 it receives
611 from 5 will beat X:2, but when speaker 4 compares Y:1:200 to Y:3:100 the MED
612 check now becomes active as the ASes match, and now Y:3:100 is preferred.
613 Speaker 4 therefore now advertises Y:3:100 to 5, which will also agrees that
614 Y:3:100 is preferred to Y:1:200, and so withdraws the latter route from 4.
615 Speaker 4 now has only X:2 and Y:3:100, and X:2 beats Y:3:100, and so speaker 4
616 implicitly updates its route to speaker 5 to X:2. Speaker 5 sees that Y:1:200
617 beats X:2 based on the ID, and advertises Y:1:200 to speaker 4, and the cycle
620 The root cause is the lack of a clear order of preference caused by how MED
621 sometimes is and sometimes is not compared, leading to this cycle in the
622 preferences between the routes:
627 /---> X:2 ---beats---> Y:3:100 --\\
630 \\---beats--- Y:1:200 <---beats---/
634 This particular type of oscillation in full-mesh iBGP topologies can be
635 avoided by speakers preferring already selected, external routes rather than
636 choosing to update to new a route based on a post-MED metric (e.g. router-ID),
637 at the cost of a non-deterministic selection process. FRR implements this, as
638 do many other implementations, so long as it is not overridden by setting
639 :clicmd:`bgp bestpath compare-routerid`, and see also
640 :ref:`bgp-route-selection`.
642 However, more complex and insidious cycles of oscillation are possible with
643 iBGP route-reflection, which are not so easily avoided. These have been
644 documented in various places. See, e.g.:
646 - [bgp-route-osci-cond]_
647 - [stable-flexible-ibgp]_
648 - [ibgp-correctness]_
650 for concrete examples and further references.
652 There is as of this writing *no* known way to use MED for its original purpose;
653 *and* reduce routing information in iBGP topologies; *and* be sure to avoid the
654 instability problems of MED due the non-transitive routing preferences it can
655 induce; in general on arbitrary networks.
657 There may be iBGP topology specific ways to reduce the instability risks, even
658 while using MED, e.g.: by constraining the reflection topology and by tuning
659 IGP costs between route-reflector clusters, see :rfc:`3345` for details. In the
660 near future, the Add-Path extension to BGP may also solve MED oscillation while
661 still allowing MED to be used as intended, by distributing "best-paths per
662 neighbour AS". This would be at the cost of distributing at least as many
663 routes to all speakers as a full-mesh iBGP would, if not more, while also
664 imposing similar CPU overheads as the "Deterministic MED" feature at each
667 More generally, the instability problems that MED can introduce on more
668 complex, non-full-mesh, iBGP topologies may be avoided either by:
670 - Setting :clicmd:`bgp always-compare-med`, however this allows MED to be compared
671 across values set by different neighbour ASes, which may not produce
672 coherent desirable results, of itself.
673 - Effectively ignoring MED by setting MED to the same value (e.g.: 0) using
674 :clicmd:`set metric METRIC` on all received routes, in combination with
675 setting :clicmd:`bgp always-compare-med` on all speakers. This is the simplest
676 and most performant way to avoid MED oscillation issues, where an AS is happy
677 not to allow neighbours to inject this problematic metric.
679 As MED is evaluated after the AS_PATH length check, another possible use for
680 MED is for intra-AS steering of routes with equal AS_PATH length, as an
681 extension of the last case above. As MED is evaluated before IGP metric, this
682 can allow cold-potato routing to be implemented to send traffic to preferred
683 hand-offs with neighbours, rather than the closest hand-off according to the
686 Note that even if action is taken to address the MED non-transitivity issues,
687 other oscillations may still be possible. E.g., on IGP cost if iBGP and IGP
688 topologies are at cross-purposes with each other - see the Flavel and Roughan
689 paper above for an example. Hence the guideline that the iBGP topology should
690 follow the IGP topology.
692 .. index:: bgp deterministic-med
693 .. clicmd:: bgp deterministic-med
695 Carry out route-selection in way that produces deterministic answers
696 locally, even in the face of MED and the lack of a well-defined order of
697 preference it can induce on routes. Without this option the preferred route
698 with MED may be determined largely by the order that routes were received
701 Setting this option will have a performance cost that may be noticeable when
702 there are many routes for each destination. Currently in FRR it is
703 implemented in a way that scales poorly as the number of routes per
704 destination increases.
706 The default is that this option is not set.
708 Note that there are other sources of indeterminism in the route selection
709 process, specifically, the preference for older and already selected routes
710 from eBGP peers, :ref:`bgp-route-selection`.
712 .. index:: bgp always-compare-med
713 .. clicmd:: bgp always-compare-med
715 Always compare the MED on routes, even when they were received from
716 different neighbouring ASes. Setting this option makes the order of
717 preference of routes more defined, and should eliminate MED induced
720 If using this option, it may also be desirable to use
721 :clicmd:`set metric METRIC` to set MED to 0 on routes received from external
724 This option can be used, together with :clicmd:`set metric METRIC` to use
725 MED as an intra-AS metric to steer equal-length AS_PATH routes to, e.g.,
729 .. _bgp-graceful-restart:
734 BGP graceful restart functionality as defined in
735 `RFC-4724 <https://tools.ietf.org/html/rfc4724/>`_ defines the mechanisms that
736 allows BGP speaker to continue to forward data packets along known routes
737 while the routing protocol information is being restored.
740 Usually, when BGP on a router restarts, all the BGP peers detect that the
741 session went down and then came up. This "down/up" transition results in a
742 "routing flap" and causes BGP route re-computation, generation of BGP routing
743 updates, and unnecessary churn to the forwarding tables.
745 The following functionality is provided by graceful restart:
747 1. The feature allows the restarting router to indicate to the helping peer the
748 routes it can preserve in its forwarding plane during control plane restart
749 by sending graceful restart capability in the OPEN message sent during
750 session establishment.
751 2. The feature allows helping router to advertise to all other peers the routes
752 received from the restarting router which are preserved in the forwarding
753 plane of the restarting router during control plane restart.
760 (R1)-----------------------------------------------------------------(R2)
762 1. BGP Graceful Restart Capability exchanged between R1 & R2.
764 <--------------------------------------------------------------------->
766 2. Kill BGP Process at R1.
768 ---------------------------------------------------------------------->
770 3. R2 Detects the above BGP Restart & verifies BGP Restarting
773 4. Start BGP Process at R1.
775 5. Re-establish the BGP session between R1 & R2.
777 <--------------------------------------------------------------------->
779 6. R2 Send initial route updates, followed by End-Of-Rib.
781 <----------------------------------------------------------------------
783 7. R1 was waiting for End-Of-Rib from R2 & which has been received
786 8. R1 now runs BGP Best-Path algorithm. Send Initial BGP Update,
787 followed by End-Of Rib
789 <--------------------------------------------------------------------->
792 .. _bgp-end-of-rib-message:
794 End-of-RIB (EOR) message
795 ^^^^^^^^^^^^^^^^^^^^^^^^
797 An UPDATE message with no reachable Network Layer Reachability Information
798 (NLRI) and empty withdrawn NLRI is specified as the End-of-RIB marker that can
799 be used by a BGP speaker to indicate to its peer the completion of the initial
800 routing update after the session is established.
802 For the IPv4 unicast address family, the End-of-RIB marker is an UPDATE message
803 with the minimum length. For any other address family, it is an UPDATE message
804 that contains only the MP_UNREACH_NLRI attribute with no withdrawn routes for
807 Although the End-of-RIB marker is specified for the purpose of BGP graceful
808 restart, it is noted that the generation of such a marker upon completion of
809 the initial update would be useful for routing convergence in general, and thus
810 the practice is recommended.
812 .. _bgp-route-selection-deferral-timer:
814 Route Selection Deferral Timer
815 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
817 Specifies the time the restarting router defers the route selection process
820 Restarting Router : The usage of route election deferral timer is specified
821 in https://tools.ietf.org/html/rfc4724#section-4.1
823 Once the session between the Restarting Speaker and the Receiving Speaker is
824 re-established, the Restarting Speaker will receive and process BGP messages
827 However, it MUST defer route selection for an address family until it either.
829 1. Receives the End-of-RIB marker from all its peers (excluding the ones with
830 the "Restart State" bit set in the received capability and excluding the ones
831 that do not advertise the graceful restart capability).
832 2. The Selection_Deferral_Timer timeout.
834 .. index:: bgp graceful-restart select-defer-time (0-3600)
835 .. clicmd:: bgp graceful-restart select-defer-time (0-3600)
837 This is command, will set deferral time to value specified.
840 .. index:: bgp graceful-restart rib-stale-time (1-3600)
841 .. clicmd:: bgp graceful-restart rib-stale-time (1-3600)
843 This is command, will set the time for which stale routes are kept in RIB.
845 .. _bgp-per-peer-graceful-restart:
847 BGP Per Peer Graceful Restart
848 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
850 Ability to enable and disable graceful restart, helper and no GR at all mode
851 functionality at peer level.
853 So bgp graceful restart can be enabled at modes global BGP level or at per
854 peer level. There are two FSM, one for BGP GR global mode and other for peer
857 Default global mode is helper and default peer per mode is inherit from global.
858 If per peer mode is configured, the GR mode of this particular peer will
859 override the global mode.
861 .. _bgp-GR-global-mode-cmd:
863 BGP GR Global Mode Commands
864 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
866 .. index:: bgp graceful-restart
867 .. clicmd:: bgp graceful-restart
869 This command will enable BGP graceful restart ifunctionality at the global
872 .. index:: bgp graceful-restart disable
873 .. clicmd:: bgp graceful-restart disable
875 This command will disable both the functionality graceful restart and helper
879 .. _bgp-GR-peer-mode-cmd:
881 BGP GR Peer Mode Commands
882 ^^^^^^^^^^^^^^^^^^^^^^^^^
884 .. index:: neighbor A.B.C.D graceful-restart
885 .. clicmd:: neighbor A.B.C.D graceful-restart
887 This command will enable BGP graceful restart ifunctionality at the peer
890 .. index:: neighbor A.B.C.D graceful-restart-helper
891 .. clicmd:: neighbor A.B.C.D graceful-restart-helper
893 This command will enable BGP graceful restart helper only functionality
896 .. index:: neighbor A.B.C.D graceful-restart-disable
897 .. clicmd:: neighbor A.B.C.D graceful-restart-disable
899 This command will disable the entire BGP graceful restart functionality
908 .. index:: network A.B.C.D/M
909 .. clicmd:: network A.B.C.D/M
911 This command adds the announcement network.
916 address-family ipv4 unicast
920 This configuration example says that network 10.0.0.0/8 will be
921 announced to all neighbors. Some vendors' routers don't advertise
922 routes if they aren't present in their IGP routing tables; `bgpd`
923 doesn't care about IGP routes when announcing its routes.
925 .. index:: no network A.B.C.D/M
926 .. clicmd:: no network A.B.C.D/M
928 .. index:: [no] bgp network import-check
929 .. clicmd:: [no] bgp network import-check
931 This configuration modifies the behavior of the network statement.
932 If you have this configured the underlying network must exist in
933 the rib. If you have the [no] form configured then BGP will not
934 check for the networks existence in the rib. For versions 7.3 and
935 before frr defaults for datacenter were the network must exist,
936 traditional did not check for existence. For versions 7.4 and beyond
937 both traditional and datacenter the network must exist.
939 .. _bgp-route-aggregation:
944 .. _bgp-route-aggregation-ipv4:
946 Route Aggregation-IPv4 Address Family
947 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
949 .. index:: aggregate-address A.B.C.D/M
950 .. clicmd:: aggregate-address A.B.C.D/M
952 This command specifies an aggregate address.
954 .. index:: aggregate-address A.B.C.D/M route-map NAME
955 .. clicmd:: aggregate-address A.B.C.D/M route-map NAME
957 Apply a route-map for an aggregated prefix.
959 .. index:: aggregate-address A.B.C.D/M origin <egp|igp|incomplete>
960 .. clicmd:: aggregate-address A.B.C.D/M origin <egp|igp|incomplete>
962 Override ORIGIN for an aggregated prefix.
964 .. index:: aggregate-address A.B.C.D/M as-set
965 .. clicmd:: aggregate-address A.B.C.D/M as-set
967 This command specifies an aggregate address. Resulting routes include
970 .. index:: aggregate-address A.B.C.D/M summary-only
971 .. clicmd:: aggregate-address A.B.C.D/M summary-only
973 This command specifies an aggregate address. Aggregated routes will
976 .. index:: no aggregate-address A.B.C.D/M
977 .. clicmd:: no aggregate-address A.B.C.D/M
979 This command removes an aggregate address.
982 This configuration example setup the aggregate-address under
988 address-family ipv4 unicast
989 aggregate-address 10.0.0.0/8
990 aggregate-address 20.0.0.0/8 as-set
991 aggregate-address 40.0.0.0/8 summary-only
992 aggregate-address 50.0.0.0/8 route-map aggr-rmap
996 .. _bgp-route-aggregation-ipv6:
998 Route Aggregation-IPv6 Address Family
999 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1001 .. index:: aggregate-address X:X::X:X/M
1002 .. clicmd:: aggregate-address X:X::X:X/M
1004 This command specifies an aggregate address.
1006 .. index:: aggregate-address X:X::X:X/M route-map NAME
1007 .. clicmd:: aggregate-address X:X::X:X/M route-map NAME
1009 Apply a route-map for an aggregated prefix.
1011 .. index:: aggregate-address X:X::X:X/M origin <egp|igp|incomplete>
1012 .. clicmd:: aggregate-address X:X::X:X/M origin <egp|igp|incomplete>
1014 Override ORIGIN for an aggregated prefix.
1016 .. index:: aggregate-address X:X::X:X/M as-set
1017 .. clicmd:: aggregate-address X:X::X:X/M as-set
1019 This command specifies an aggregate address. Resulting routes include
1022 .. index:: aggregate-address X:X::X:X/M summary-only
1023 .. clicmd:: aggregate-address X:X::X:X/M summary-only
1025 This command specifies an aggregate address. Aggregated routes will
1028 .. index:: no aggregate-address X:X::X:X/M
1029 .. clicmd:: no aggregate-address X:X::X:X/M
1031 This command removes an aggregate address.
1034 This configuration example setup the aggregate-address under
1035 ipv6 address-family.
1040 address-family ipv6 unicast
1041 aggregate-address 10::0/64
1042 aggregate-address 20::0/64 as-set
1043 aggregate-address 40::0/64 summary-only
1044 aggregate-address 50::0/64 route-map aggr-rmap
1047 .. _bgp-redistribute-to-bgp:
1052 .. index:: redistribute kernel
1053 .. clicmd:: redistribute kernel
1055 Redistribute kernel route to BGP process.
1057 .. index:: redistribute static
1058 .. clicmd:: redistribute static
1060 Redistribute static route to BGP process.
1062 .. index:: redistribute connected
1063 .. clicmd:: redistribute connected
1065 Redistribute connected route to BGP process.
1067 .. index:: redistribute rip
1068 .. clicmd:: redistribute rip
1070 Redistribute RIP route to BGP process.
1072 .. index:: redistribute ospf
1073 .. clicmd:: redistribute ospf
1075 Redistribute OSPF route to BGP process.
1077 .. index:: redistribute vnc
1078 .. clicmd:: redistribute vnc
1080 Redistribute VNC routes to BGP process.
1082 .. index:: redistribute vnc-direct
1083 .. clicmd:: redistribute vnc-direct
1085 Redistribute VNC direct (not via zebra) routes to BGP process.
1087 .. index:: update-delay MAX-DELAY
1088 .. clicmd:: update-delay MAX-DELAY
1090 .. index:: update-delay MAX-DELAY ESTABLISH-WAIT
1091 .. clicmd:: update-delay MAX-DELAY ESTABLISH-WAIT
1093 This feature is used to enable read-only mode on BGP process restart or when
1094 BGP process is cleared using 'clear ip bgp \*'. When applicable, read-only
1095 mode would begin as soon as the first peer reaches Established status and a
1096 timer for max-delay seconds is started.
1098 During this mode BGP doesn't run any best-path or generate any updates to its
1099 peers. This mode continues until:
1101 1. All the configured peers, except the shutdown peers, have sent explicit EOR
1102 (End-Of-RIB) or an implicit-EOR. The first keep-alive after BGP has reached
1103 Established is considered an implicit-EOR.
1104 If the establish-wait optional value is given, then BGP will wait for
1105 peers to reach established from the beginning of the update-delay till the
1106 establish-wait period is over, i.e. the minimum set of established peers for
1107 which EOR is expected would be peers established during the establish-wait
1108 window, not necessarily all the configured neighbors.
1109 2. max-delay period is over.
1111 On hitting any of the above two conditions, BGP resumes the decision process
1112 and generates updates to its peers.
1114 Default max-delay is 0, i.e. the feature is off by default.
1116 .. index:: table-map ROUTE-MAP-NAME
1117 .. clicmd:: table-map ROUTE-MAP-NAME
1119 This feature is used to apply a route-map on route updates from BGP to
1120 Zebra. All the applicable match operations are allowed, such as match on
1121 prefix, next-hop, communities, etc. Set operations for this attach-point are
1122 limited to metric and next-hop only. Any operation of this feature does not
1123 affect BGPs internal RIB.
1125 Supported for ipv4 and ipv6 address families. It works on multi-paths as
1126 well, however, metric setting is based on the best-path only.
1133 .. _bgp-defining-peers:
1138 .. index:: neighbor PEER remote-as ASN
1139 .. clicmd:: neighbor PEER remote-as ASN
1141 Creates a new neighbor whose remote-as is ASN. PEER can be an IPv4 address
1142 or an IPv6 address or an interface to use for the connection.
1147 neighbor 10.0.0.1 remote-as 2
1149 In this case my router, in AS-1, is trying to peer with AS-2 at 10.0.0.1.
1151 This command must be the first command used when configuring a neighbor. If
1152 the remote-as is not specified, *bgpd* will complain like this: ::
1154 can't find neighbor 10.0.0.1
1156 .. index:: neighbor PEER remote-as internal
1157 .. clicmd:: neighbor PEER remote-as internal
1159 Create a peer as you would when you specify an ASN, except that if the
1160 peers ASN is different than mine as specified under the :clicmd:`router bgp ASN`
1161 command the connection will be denied.
1163 .. index:: neighbor PEER remote-as external
1164 .. clicmd:: neighbor PEER remote-as external
1166 Create a peer as you would when you specify an ASN, except that if the
1167 peers ASN is the same as mine as specified under the :clicmd:`router bgp ASN`
1168 command the connection will be denied.
1170 .. index:: [no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group PGNAME
1171 .. clicmd:: [no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group PGNAME
1173 Accept connections from any peers in the specified prefix. Configuration
1174 from the specified peer-group is used to configure these peers.
1178 When using BGP listen ranges, if the associated peer group has TCP MD5
1179 authentication configured, your kernel must support this on prefixes. On
1180 Linux, this support was added in kernel version 4.14. If your kernel does
1181 not support this feature you will get a warning in the log file, and the
1182 listen range will only accept connections from peers without MD5 configured.
1184 Additionally, we have observed that when using this option at scale (several
1185 hundred peers) the kernel may hit its option memory limit. In this situation
1186 you will see error messages like:
1188 ``bgpd: sockopt_tcp_signature: setsockopt(23): Cannot allocate memory``
1190 In this case you need to increase the value of the sysctl
1191 ``net.core.optmem_max`` to allow the kernel to allocate the necessary option
1194 .. index:: [no] coalesce-time (0-4294967295)
1195 .. clicmd:: [no] coalesce-time (0-4294967295)
1197 The time in milliseconds that BGP will delay before deciding what peers
1198 can be put into an update-group together in order to generate a single
1199 update for them. The default time is 1000.
1201 .. _bgp-configuring-peers:
1206 .. index:: [no] neighbor PEER shutdown [message MSG...]
1207 .. clicmd:: [no] neighbor PEER shutdown [message MSG...]
1209 Shutdown the peer. We can delete the neighbor's configuration by
1210 ``no neighbor PEER remote-as ASN`` but all configuration of the neighbor
1211 will be deleted. When you want to preserve the configuration, but want to
1212 drop the BGP peer, use this syntax.
1214 Optionally you can specify a shutdown message `MSG`.
1216 .. index:: [no] neighbor PEER disable-connected-check
1217 .. clicmd:: [no] neighbor PEER disable-connected-check
1219 Allow peerings between directly connected eBGP peers using loopback
1222 .. index:: [no] neighbor PEER ebgp-multihop
1223 .. clicmd:: [no] neighbor PEER ebgp-multihop
1225 Specifying ``ebgp-multihop`` allows sessions with eBGP neighbors to
1226 establish when they are multiple hops away. When the neighbor is not
1227 directly connected and this knob is not enabled, the session will not
1230 .. index:: [no] neighbor PEER description ...
1231 .. clicmd:: [no] neighbor PEER description ...
1233 Set description of the peer.
1235 .. index:: [no] neighbor PEER version VERSION
1236 .. clicmd:: [no] neighbor PEER version VERSION
1238 Set up the neighbor's BGP version. `version` can be `4`, `4+` or `4-`. BGP
1239 version `4` is the default value used for BGP peering. BGP version `4+`
1240 means that the neighbor supports Multiprotocol Extensions for BGP-4. BGP
1241 version `4-` is similar but the neighbor speaks the old Internet-Draft
1242 revision 00's Multiprotocol Extensions for BGP-4. Some routing software is
1243 still using this version.
1245 .. index:: [no] neighbor PEER interface IFNAME
1246 .. clicmd:: [no] neighbor PEER interface IFNAME
1248 When you connect to a BGP peer over an IPv6 link-local address, you have to
1249 specify the IFNAME of the interface used for the connection. To specify
1250 IPv4 session addresses, see the ``neighbor PEER update-source`` command
1253 This command is deprecated and may be removed in a future release. Its use
1256 .. index:: [no] neighbor PEER next-hop-self [all]
1257 .. clicmd:: [no] neighbor PEER next-hop-self [all]
1259 This command specifies an announced route's nexthop as being equivalent to
1260 the address of the bgp router if it is learned via eBGP. If the optional
1261 keyword `all` is specified the modification is done also for routes learned
1264 .. index:: neighbor PEER attribute-unchanged [{as-path|next-hop|med}]
1265 .. clicmd:: neighbor PEER attribute-unchanged [{as-path|next-hop|med}]
1267 This command specifies attributes to be left unchanged for advertisements
1268 sent to a peer. Use this to leave the next-hop unchanged in ipv6
1269 configurations, as the route-map directive to leave the next-hop unchanged
1270 is only available for ipv4.
1272 .. index:: [no] neighbor PEER update-source <IFNAME|ADDRESS>
1273 .. clicmd:: [no] neighbor PEER update-source <IFNAME|ADDRESS>
1275 Specify the IPv4 source address to use for the :abbr:`BGP` session to this
1276 neighbour, may be specified as either an IPv4 address directly or as an
1277 interface name (in which case the *zebra* daemon MUST be running in order
1278 for *bgpd* to be able to retrieve interface state).
1283 neighbor foo update-source 192.168.0.1
1284 neighbor bar update-source lo0
1287 .. index:: [no] neighbor PEER default-originate
1288 .. clicmd:: [no] neighbor PEER default-originate
1290 *bgpd*'s default is to not announce the default route (0.0.0.0/0) even if it
1291 is in routing table. When you want to announce default routes to the peer,
1294 .. index:: neighbor PEER port PORT
1295 .. clicmd:: neighbor PEER port PORT
1297 .. index:: [no] neighbor PEER password PASSWORD
1298 .. clicmd:: [no] neighbor PEER password PASSWORD
1300 Set a MD5 password to be used with the tcp socket that is being used
1301 to connect to the remote peer. Please note if you are using this
1302 command with a large number of peers on linux you should consider
1303 modifying the `net.core.optmem_max` sysctl to a larger value to
1304 avoid out of memory errors from the linux kernel.
1306 .. index:: neighbor PEER send-community
1307 .. clicmd:: neighbor PEER send-community
1309 .. index:: [no] neighbor PEER weight WEIGHT
1310 .. clicmd:: [no] neighbor PEER weight WEIGHT
1312 This command specifies a default `weight` value for the neighbor's routes.
1314 .. index:: [no] neighbor PEER maximum-prefix NUMBER
1315 .. clicmd:: [no] neighbor PEER maximum-prefix NUMBER
1317 Sets a maximum number of prefixes we can receive from a given peer. If this
1318 number is exceeded, the BGP session will be destroyed.
1320 In practice, it is generally preferable to use a prefix-list to limit what
1321 prefixes are received from the peer instead of using this knob. Tearing down
1322 the BGP session when a limit is exceeded is far more destructive than merely
1323 rejecting undesired prefixes. The prefix-list method is also much more
1324 granular and offers much smarter matching criterion than number of received
1325 prefixes, making it more suited to implementing policy.
1327 .. index:: [no] neighbor PEER maximum-prefix-out NUMBER
1328 .. clicmd:: [no] neighbor PEER maximum-prefix-out NUMBER
1330 Sets a maximum number of prefixes we can send to a given peer.
1332 .. index:: [no] neighbor PEER local-as AS-NUMBER [no-prepend] [replace-as]
1333 .. clicmd:: [no] neighbor PEER local-as AS-NUMBER [no-prepend] [replace-as]
1335 Specify an alternate AS for this BGP process when interacting with the
1336 specified peer. With no modifiers, the specified local-as is prepended to
1337 the received AS_PATH when receiving routing updates from the peer, and
1338 prepended to the outgoing AS_PATH (after the process local AS) when
1339 transmitting local routes to the peer.
1341 If the no-prepend attribute is specified, then the supplied local-as is not
1342 prepended to the received AS_PATH.
1344 If the replace-as attribute is specified, then only the supplied local-as is
1345 prepended to the AS_PATH when transmitting local-route updates to this peer.
1347 Note that replace-as can only be specified if no-prepend is.
1349 This command is only allowed for eBGP peers.
1351 .. index:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> as-override
1352 .. clicmd:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> as-override
1354 Override AS number of the originating router with the local AS number.
1356 Usually this configuration is used in PEs (Provider Edge) to replace
1357 the incoming customer AS number so the connected CE (Customer Edge)
1358 can use the same AS number as the other customer sites. This allows
1359 customers of the provider network to use the same AS number across
1362 This command is only allowed for eBGP peers.
1364 .. index:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> allowas-in [<(1-10)|origin>]
1365 .. clicmd:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> allowas-in [<(1-10)|origin>]
1367 Accept incoming routes with AS path containing AS number with the same value
1368 as the current system AS.
1370 This is used when you want to use the same AS number in your sites, but you
1371 can't connect them directly. This is an alternative to
1372 `neighbor WORD as-override`.
1374 The parameter `(1-10)` configures the amount of accepted occurences of the
1375 system AS number in AS path.
1377 The parameter `origin` configures BGP to only accept routes originated with
1378 the same AS number as the system.
1380 This command is only allowed for eBGP peers.
1382 .. index:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> addpath-tx-all-paths
1383 .. clicmd:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> addpath-tx-all-paths
1385 Configure BGP to send all known paths to neighbor in order to preserve multi
1386 path capabilities inside a network.
1388 .. index:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> addpath-tx-bestpath-per-AS
1389 .. clicmd:: [no] neighbor <A.B.C.D|X:X::X:X|WORD> addpath-tx-bestpath-per-AS
1391 Configure BGP to send best known paths to neighbor in order to preserve multi
1392 path capabilities inside a network.
1394 .. index:: [no] neighbor PEER ttl-security hops NUMBER
1395 .. clicmd:: [no] neighbor PEER ttl-security hops NUMBER
1397 This command enforces Generalized TTL Security Mechanism (GTSM), as
1398 specified in RFC 5082. With this command, only neighbors that are the
1399 specified number of hops away will be allowed to become neighbors. This
1400 command is mutually exclusive with *ebgp-multihop*.
1402 .. index:: [no] neighbor PEER capability extended-nexthop
1403 .. clicmd:: [no] neighbor PEER capability extended-nexthop
1405 Allow bgp to negotiate the extended-nexthop capability with it's peer.
1406 If you are peering over a v6 LL address then this capability is turned
1407 on automatically. If you are peering over a v6 Global Address then
1408 turning on this command will allow BGP to install v4 routes with
1409 v6 nexthops if you do not have v4 configured on interfaces.
1411 .. index:: [no] bgp fast-external-failover
1412 .. clicmd:: [no] bgp fast-external-failover
1414 This command causes bgp to not take down ebgp peers immediately
1415 when a link flaps. `bgp fast-external-failover` is the default
1416 and will not be displayed as part of a `show run`. The no form
1417 of the command turns off this ability.
1419 .. index:: [no] bgp default ipv4-unicast
1420 .. clicmd:: [no] bgp default ipv4-unicast
1422 This command allows the user to specify that v4 peering is turned
1423 on by default or not. This command defaults to on and is not displayed.
1424 The `no bgp default ipv4-unicast` form of the command is displayed.
1426 .. index:: [no] bgp default show-hostname
1427 .. clicmd:: [no] bgp default show-hostname
1429 This command shows the hostname of the peer in certain BGP commands
1430 outputs. It's easier to troubleshoot if you have a number of BGP peers.
1432 .. index:: [no] bgp default show-nexthop-hostname
1433 .. clicmd:: [no] bgp default show-nexthop-hostname
1435 This command shows the hostname of the next-hop in certain BGP commands
1436 outputs. It's easier to troubleshoot if you have a number of BGP peers
1437 and a number of routes to check.
1439 .. index:: [no] neighbor PEER advertisement-interval (0-600)
1440 .. clicmd:: [no] neighbor PEER advertisement-interval (0-600)
1442 Setup the minimum route advertisement interval(mrai) for the
1443 peer in question. This number is between 0 and 600 seconds,
1444 with the default advertisement interval being 0.
1446 Displaying Information about Peers
1447 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1449 .. index:: show bgp <afi> <safi> neighbors WORD bestpath-routes [json] [wide]
1450 .. clicmd:: show bgp <afi> <safi> neighbors WORD bestpath-routes [json] [wide]
1452 For the given neighbor, WORD, that is specified list the routes selected
1453 by BGP as having the best path.
1455 .. _bgp-peer-filtering:
1460 .. index:: neighbor PEER distribute-list NAME [in|out]
1461 .. clicmd:: neighbor PEER distribute-list NAME [in|out]
1463 This command specifies a distribute-list for the peer. `direct` is
1466 .. index:: neighbor PEER prefix-list NAME [in|out]
1467 .. clicmd:: neighbor PEER prefix-list NAME [in|out]
1469 .. index:: neighbor PEER filter-list NAME [in|out]
1470 .. clicmd:: neighbor PEER filter-list NAME [in|out]
1472 .. index:: neighbor PEER route-map NAME [in|out]
1473 .. clicmd:: neighbor PEER route-map NAME [in|out]
1475 Apply a route-map on the neighbor. `direct` must be `in` or `out`.
1477 .. index:: bgp route-reflector allow-outbound-policy
1478 .. clicmd:: bgp route-reflector allow-outbound-policy
1480 By default, attribute modification via route-map policy out is not reflected
1481 on reflected routes. This option allows the modifications to be reflected as
1482 well. Once enabled, it affects all reflected routes.
1484 .. index:: [no] neighbor PEER sender-as-path-loop-detection
1485 .. clicmd:: [no] neighbor PEER sender-as-path-loop-detection
1487 Enable the detection of sender side AS path loops and filter the
1488 bad routes before they are sent.
1490 This setting is disabled by default.
1497 Peer groups are used to help improve scaling by generating the same
1498 update information to all members of a peer group. Note that this means
1499 that the routes generated by a member of a peer group will be sent back
1500 to that originating peer with the originator identifier attribute set to
1501 indicated the originating peer. All peers not associated with a
1502 specific peer group are treated as belonging to a default peer group,
1503 and will share updates.
1505 .. index:: neighbor WORD peer-group
1506 .. clicmd:: neighbor WORD peer-group
1508 This command defines a new peer group.
1510 .. index:: neighbor PEER peer-group PGNAME
1511 .. clicmd:: neighbor PEER peer-group PGNAME
1513 This command bind specific peer to peer group WORD.
1515 .. index:: neighbor PEER solo
1516 .. clicmd:: neighbor PEER solo
1518 This command is used to indicate that routes advertised by the peer
1519 should not be reflected back to the peer. This command only is only
1520 meaningful when there is a single peer defined in the peer-group.
1522 Capability Negotiation
1523 ^^^^^^^^^^^^^^^^^^^^^^
1525 .. index:: neighbor PEER strict-capability-match
1526 .. clicmd:: neighbor PEER strict-capability-match
1528 .. index:: no neighbor PEER strict-capability-match
1529 .. clicmd:: no neighbor PEER strict-capability-match
1531 Strictly compares remote capabilities and local capabilities. If
1532 capabilities are different, send Unsupported Capability error then reset
1535 You may want to disable sending Capability Negotiation OPEN message optional
1536 parameter to the peer when remote peer does not implement Capability
1537 Negotiation. Please use *dont-capability-negotiate* command to disable the
1540 .. index:: [no] neighbor PEER dont-capability-negotiate
1541 .. clicmd:: [no] neighbor PEER dont-capability-negotiate
1543 Suppress sending Capability Negotiation as OPEN message optional parameter
1544 to the peer. This command only affects the peer is configured other than
1545 IPv4 unicast configuration.
1547 When remote peer does not have capability negotiation feature, remote peer
1548 will not send any capabilities at all. In that case, bgp configures the peer
1549 with configured capabilities.
1551 You may prefer locally configured capabilities more than the negotiated
1552 capabilities even though remote peer sends capabilities. If the peer is
1553 configured by *override-capability*, *bgpd* ignores received capabilities
1554 then override negotiated capabilities with configured values.
1556 Additionally the operator should be reminded that this feature fundamentally
1557 disables the ability to use widely deployed BGP features. BGP unnumbered,
1558 hostname support, AS4, Addpath, Route Refresh, ORF, Dynamic Capabilities,
1559 and graceful restart.
1561 .. index:: neighbor PEER override-capability
1562 .. clicmd:: neighbor PEER override-capability
1564 .. index:: no neighbor PEER override-capability
1565 .. clicmd:: no neighbor PEER override-capability
1567 Override the result of Capability Negotiation with local configuration.
1568 Ignore remote peer's capability value.
1570 .. _bgp-as-path-access-lists:
1572 AS Path Access Lists
1573 --------------------
1575 AS path access list is user defined AS path.
1577 .. index:: bgp as-path access-list WORD permit|deny LINE
1578 .. clicmd:: bgp as-path access-list WORD permit|deny LINE
1580 This command defines a new AS path access list.
1582 .. index:: no bgp as-path access-list WORD
1583 .. clicmd:: no bgp as-path access-list WORD
1585 .. index:: no bgp as-path access-list WORD permit|deny LINE
1586 .. clicmd:: no bgp as-path access-list WORD permit|deny LINE
1588 .. _bgp-bogon-filter-example:
1590 Bogon ASN filter policy configuration example
1591 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1595 bgp as-path access-list 99 permit _0_
1596 bgp as-path access-list 99 permit _23456_
1597 bgp as-path access-list 99 permit _1310[0-6][0-9]_|_13107[0-1]_
1599 .. _bgp-using-as-path-in-route-map:
1601 Using AS Path in Route Map
1602 --------------------------
1604 .. index:: [no] match as-path WORD
1605 .. clicmd:: [no] match as-path WORD
1607 For a given as-path, WORD, match it on the BGP as-path given for the prefix
1608 and if it matches do normal route-map actions. The no form of the command
1609 removes this match from the route-map.
1611 .. index:: [no] set as-path prepend AS-PATH
1612 .. clicmd:: [no] set as-path prepend AS-PATH
1614 Prepend the given string of AS numbers to the AS_PATH of the BGP path's NLRI.
1615 The no form of this command removes this set operation from the route-map.
1617 .. index:: [no] set as-path prepend last-as NUM
1618 .. clicmd:: [no] set as-path prepend last-as NUM
1620 Prepend the existing last AS number (the leftmost ASN) to the AS_PATH.
1621 The no form of this command removes this set operation from the route-map.
1623 .. _bgp-communities-attribute:
1625 Communities Attribute
1626 ---------------------
1628 The BGP communities attribute is widely used for implementing policy routing.
1629 Network operators can manipulate BGP communities attribute based on their
1630 network policy. BGP communities attribute is defined in :rfc:`1997` and
1631 :rfc:`1998`. It is an optional transitive attribute, therefore local policy can
1632 travel through different autonomous system.
1634 The communities attribute is a set of communities values. Each community value
1635 is 4 octet long. The following format is used to define the community value.
1638 This format represents 4 octet communities value. ``AS`` is high order 2
1639 octet in digit format. ``VAL`` is low order 2 octet in digit format. This
1640 format is useful to define AS oriented policy value. For example,
1641 ``7675:80`` can be used when AS 7675 wants to pass local policy value 80 to
1645 ``internet`` represents well-known communities value 0.
1647 ``graceful-shutdown``
1648 ``graceful-shutdown`` represents well-known communities value
1649 ``GRACEFUL_SHUTDOWN`` ``0xFFFF0000`` ``65535:0``. :rfc:`8326` implements
1650 the purpose Graceful BGP Session Shutdown to reduce the amount of
1651 lost traffic when taking BGP sessions down for maintenance. The use
1652 of the community needs to be supported from your peers side to
1653 actually have any effect.
1656 ``accept-own`` represents well-known communities value ``ACCEPT_OWN``
1657 ``0xFFFF0001`` ``65535:1``. :rfc:`7611` implements a way to signal
1658 to a router to accept routes with a local nexthop address. This
1659 can be the case when doing policing and having traffic having a
1660 nexthop located in another VRF but still local interface to the
1661 router. It is recommended to read the RFC for full details.
1663 ``route-filter-translated-v4``
1664 ``route-filter-translated-v4`` represents well-known communities value
1665 ``ROUTE_FILTER_TRANSLATED_v4`` ``0xFFFF0002`` ``65535:2``.
1668 ``route-filter-v4`` represents well-known communities value
1669 ``ROUTE_FILTER_v4`` ``0xFFFF0003`` ``65535:3``.
1671 ``route-filter-translated-v6``
1672 ``route-filter-translated-v6`` represents well-known communities value
1673 ``ROUTE_FILTER_TRANSLATED_v6`` ``0xFFFF0004`` ``65535:4``.
1676 ``route-filter-v6`` represents well-known communities value
1677 ``ROUTE_FILTER_v6`` ``0xFFFF0005`` ``65535:5``.
1680 ``llgr-stale`` represents well-known communities value ``LLGR_STALE``
1681 ``0xFFFF0006`` ``65535:6``.
1682 Assigned and intended only for use with routers supporting the
1683 Long-lived Graceful Restart Capability as described in
1684 [Draft-IETF-uttaro-idr-bgp-persistence]_.
1685 Routers receiving routes with this community may (depending on
1686 implementation) choose allow to reject or modify routes on the
1687 presence or absence of this community.
1690 ``no-llgr`` represents well-known communities value ``NO_LLGR``
1691 ``0xFFFF0007`` ``65535:7``.
1692 Assigned and intended only for use with routers supporting the
1693 Long-lived Graceful Restart Capability as described in
1694 [Draft-IETF-uttaro-idr-bgp-persistence]_.
1695 Routers receiving routes with this community may (depending on
1696 implementation) choose allow to reject or modify routes on the
1697 presence or absence of this community.
1699 ``accept-own-nexthop``
1700 ``accept-own-nexthop`` represents well-known communities value
1701 ``accept-own-nexthop`` ``0xFFFF0008`` ``65535:8``.
1702 [Draft-IETF-agrewal-idr-accept-own-nexthop]_ describes
1703 how to tag and label VPN routes to be able to send traffic between VRFs
1704 via an internal layer 2 domain on the same PE device. Refer to
1705 [Draft-IETF-agrewal-idr-accept-own-nexthop]_ for full details.
1708 ``blackhole`` represents well-known communities value ``BLACKHOLE``
1709 ``0xFFFF029A`` ``65535:666``. :rfc:`7999` documents sending prefixes to
1710 EBGP peers and upstream for the purpose of blackholing traffic.
1711 Prefixes tagged with the this community should normally not be
1712 re-advertised from neighbors of the originating network. It is
1713 recommended upon receiving prefixes tagged with this community to
1714 add ``NO_EXPORT`` and ``NO_ADVERTISE``.
1717 ``no-export`` represents well-known communities value ``NO_EXPORT``
1718 ``0xFFFFFF01``. All routes carry this value must not be advertised to
1719 outside a BGP confederation boundary. If neighboring BGP peer is part of BGP
1720 confederation, the peer is considered as inside a BGP confederation
1721 boundary, so the route will be announced to the peer.
1724 ``no-advertise`` represents well-known communities value ``NO_ADVERTISE``
1725 ``0xFFFFFF02``. All routes carry this value must not be advertise to other
1729 ``local-AS`` represents well-known communities value ``NO_EXPORT_SUBCONFED``
1730 ``0xFFFFFF03``. All routes carry this value must not be advertised to
1731 external BGP peers. Even if the neighboring router is part of confederation,
1732 it is considered as external BGP peer, so the route will not be announced to
1736 ``no-peer`` represents well-known communities value ``NOPEER``
1737 ``0xFFFFFF04`` ``65535:65284``. :rfc:`3765` is used to communicate to
1738 another network how the originating network want the prefix propagated.
1740 When the communities attribute is received duplicate community values in the
1741 attribute are ignored and value is sorted in numerical order.
1743 .. [Draft-IETF-uttaro-idr-bgp-persistence] <https://tools.ietf.org/id/draft-uttaro-idr-bgp-persistence-04.txt>
1744 .. [Draft-IETF-agrewal-idr-accept-own-nexthop] <https://tools.ietf.org/id/draft-agrewal-idr-accept-own-nexthop-00.txt>
1746 .. _bgp-community-lists:
1750 Community lists are user defined lists of community attribute values. These
1751 lists can be used for matching or manipulating the communities attribute in
1754 There are two types of community list:
1757 This type accepts an explicit value for the attribute.
1760 This type accepts a regular expression. Because the regex must be
1761 interpreted on each use expanded community lists are slower than standard
1764 .. index:: bgp community-list standard NAME permit|deny COMMUNITY
1765 .. clicmd:: bgp community-list standard NAME permit|deny COMMUNITY
1767 This command defines a new standard community list. ``COMMUNITY`` is
1768 communities value. The ``COMMUNITY`` is compiled into community structure.
1769 We can define multiple community list under same name. In that case match
1770 will happen user defined order. Once the community list matches to
1771 communities attribute in BGP updates it return permit or deny by the
1772 community list definition. When there is no matched entry, deny will be
1773 returned. When ``COMMUNITY`` is empty it matches to any routes.
1775 .. index:: bgp community-list expanded NAME permit|deny COMMUNITY
1776 .. clicmd:: bgp community-list expanded NAME permit|deny COMMUNITY
1778 This command defines a new expanded community list. ``COMMUNITY`` is a
1779 string expression of communities attribute. ``COMMUNITY`` can be a regular
1780 expression (:ref:`bgp-regular-expressions`) to match the communities
1781 attribute in BGP updates. The expanded community is only used to filter,
1785 It is recommended to use the more explicit versions of this command.
1787 .. index:: bgp community-list NAME permit|deny COMMUNITY
1788 .. clicmd:: bgp community-list NAME permit|deny COMMUNITY
1790 When the community list type is not specified, the community list type is
1791 automatically detected. If ``COMMUNITY`` can be compiled into communities
1792 attribute, the community list is defined as a standard community list.
1793 Otherwise it is defined as an expanded community list. This feature is left
1794 for backward compatibility. Use of this feature is not recommended.
1797 .. index:: no bgp community-list [standard|expanded] NAME
1798 .. clicmd:: no bgp community-list [standard|expanded] NAME
1800 Deletes the community list specified by ``NAME``. All community lists share
1801 the same namespace, so it's not necessary to specify ``standard`` or
1802 ``expanded``; these modifiers are purely aesthetic.
1804 .. index:: show bgp community-list [NAME detail]
1805 .. clicmd:: show bgp community-list [NAME detail]
1807 Displays community list information. When ``NAME`` is specified the
1808 specified community list's information is shown.
1812 # show bgp community-list
1813 Named Community standard list CLIST
1814 permit 7675:80 7675:100 no-export
1816 Named Community expanded list EXPAND
1819 # show bgp community-list CLIST detail
1820 Named Community standard list CLIST
1821 permit 7675:80 7675:100 no-export
1825 .. _bgp-numbered-community-lists:
1827 Numbered Community Lists
1828 ^^^^^^^^^^^^^^^^^^^^^^^^
1830 When number is used for BGP community list name, the number has
1831 special meanings. Community list number in the range from 1 and 99 is
1832 standard community list. Community list number in the range from 100
1833 to 199 is expanded community list. These community lists are called
1834 as numbered community lists. On the other hand normal community lists
1835 is called as named community lists.
1837 .. index:: bgp community-list (1-99) permit|deny COMMUNITY
1838 .. clicmd:: bgp community-list (1-99) permit|deny COMMUNITY
1840 This command defines a new community list. The argument to (1-99) defines
1841 the list identifier.
1843 .. index:: bgp community-list (100-199) permit|deny COMMUNITY
1844 .. clicmd:: bgp community-list (100-199) permit|deny COMMUNITY
1846 This command defines a new expanded community list. The argument to
1847 (100-199) defines the list identifier.
1849 .. _bgp-using-communities-in-route-map:
1851 Using Communities in Route Maps
1852 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1854 In :ref:`route-map` we can match on or set the BGP communities attribute. Using
1855 this feature network operator can implement their network policy based on BGP
1856 communities attribute.
1858 The following commands can be used in route maps:
1860 .. index:: match community WORD exact-match [exact-match]
1861 .. clicmd:: match community WORD exact-match [exact-match]
1863 This command perform match to BGP updates using community list WORD. When
1864 the one of BGP communities value match to the one of communities value in
1865 community list, it is match. When `exact-match` keyword is specified, match
1866 happen only when BGP updates have completely same communities value
1867 specified in the community list.
1869 .. index:: set community <none|COMMUNITY> additive
1870 .. clicmd:: set community <none|COMMUNITY> additive
1872 This command sets the community value in BGP updates. If the attribute is
1873 already configured, the newly provided value replaces the old one unless the
1874 ``additive`` keyword is specified, in which case the new value is appended
1875 to the existing value.
1877 If ``none`` is specified as the community value, the communities attribute
1880 It is not possible to set an expanded community list.
1882 .. index:: set comm-list WORD delete
1883 .. clicmd:: set comm-list WORD delete
1885 This command remove communities value from BGP communities attribute. The
1886 ``word`` is community list name. When BGP route's communities value matches
1887 to the community list ``word``, the communities value is removed. When all
1888 of communities value is removed eventually, the BGP update's communities
1889 attribute is completely removed.
1891 .. _bgp-communities-example:
1893 Example Configuration
1894 ^^^^^^^^^^^^^^^^^^^^^
1896 The following configuration is exemplary of the most typical usage of BGP
1897 communities attribute. In the example, AS 7675 provides an upstream Internet
1898 connection to AS 100. When the following configuration exists in AS 7675, the
1899 network operator of AS 100 can set local preference in AS 7675 network by
1900 setting BGP communities attribute to the updates.
1905 neighbor 192.168.0.1 remote-as 100
1906 address-family ipv4 unicast
1907 neighbor 192.168.0.1 route-map RMAP in
1910 bgp community-list 70 permit 7675:70
1911 bgp community-list 70 deny
1912 bgp community-list 80 permit 7675:80
1913 bgp community-list 80 deny
1914 bgp community-list 90 permit 7675:90
1915 bgp community-list 90 deny
1917 route-map RMAP permit 10
1919 set local-preference 70
1921 route-map RMAP permit 20
1923 set local-preference 80
1925 route-map RMAP permit 30
1927 set local-preference 90
1930 The following configuration announces ``10.0.0.0/8`` from AS 100 to AS 7675.
1931 The route has communities value ``7675:80`` so when above configuration exists
1932 in AS 7675, the announced routes' local preference value will be set to 80.
1938 neighbor 192.168.0.2 remote-as 7675
1939 address-family ipv4 unicast
1940 neighbor 192.168.0.2 route-map RMAP out
1943 ip prefix-list PLIST permit 10.0.0.0/8
1945 route-map RMAP permit 10
1946 match ip address prefix-list PLIST
1947 set community 7675:80
1950 The following configuration is an example of BGP route filtering using
1951 communities attribute. This configuration only permit BGP routes which has BGP
1952 communities value ``0:80`` or ``0:90``. The network operator can set special
1953 internal communities value at BGP border router, then limit the BGP route
1954 announcements into the internal network.
1959 neighbor 192.168.0.1 remote-as 100
1960 address-family ipv4 unicast
1961 neighbor 192.168.0.1 route-map RMAP in
1964 bgp community-list 1 permit 0:80 0:90
1966 route-map RMAP permit in
1970 The following example filters BGP routes which have a community value of
1971 ``1:1``. When there is no match community-list returns ``deny``. To avoid
1972 filtering all routes, a ``permit`` line is set at the end of the
1978 neighbor 192.168.0.1 remote-as 100
1979 address-family ipv4 unicast
1980 neighbor 192.168.0.1 route-map RMAP in
1983 bgp community-list standard FILTER deny 1:1
1984 bgp community-list standard FILTER permit
1986 route-map RMAP permit 10
1987 match community FILTER
1990 The communities value keyword ``internet`` has special meanings in standard
1991 community lists. In the below example ``internet`` matches all BGP routes even
1992 if the route does not have communities attribute at all. So community list
1993 ``INTERNET`` is the same as ``FILTER`` in the previous example.
1997 bgp community-list standard INTERNET deny 1:1
1998 bgp community-list standard INTERNET permit internet
2001 The following configuration is an example of communities value deletion. With
2002 this configuration the community values ``100:1`` and ``100:2`` are removed
2003 from BGP updates. For communities value deletion, only ``permit``
2004 community-list is used. ``deny`` community-list is ignored.
2009 neighbor 192.168.0.1 remote-as 100
2010 address-family ipv4 unicast
2011 neighbor 192.168.0.1 route-map RMAP in
2014 bgp community-list standard DEL permit 100:1 100:2
2016 route-map RMAP permit 10
2017 set comm-list DEL delete
2020 .. _bgp-extended-communities-attribute:
2022 Extended Communities Attribute
2023 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2025 BGP extended communities attribute is introduced with MPLS VPN/BGP technology.
2026 MPLS VPN/BGP expands capability of network infrastructure to provide VPN
2027 functionality. At the same time it requires a new framework for policy routing.
2028 With BGP Extended Communities Attribute we can use Route Target or Site of
2029 Origin for implementing network policy for MPLS VPN/BGP.
2031 BGP Extended Communities Attribute is similar to BGP Communities Attribute. It
2032 is an optional transitive attribute. BGP Extended Communities Attribute can
2033 carry multiple Extended Community value. Each Extended Community value is
2036 BGP Extended Communities Attribute provides an extended range compared with BGP
2037 Communities Attribute. Adding to that there is a type field in each value to
2038 provides community space structure.
2040 There are two format to define Extended Community value. One is AS based format
2041 the other is IP address based format.
2044 This is a format to define AS based Extended Community value. ``AS`` part
2045 is 2 octets Global Administrator subfield in Extended Community value.
2046 ``VAL`` part is 4 octets Local Administrator subfield. ``7675:100``
2047 represents AS 7675 policy value 100.
2050 This is a format to define IP address based Extended Community value.
2051 ``IP-Address`` part is 4 octets Global Administrator subfield. ``VAL`` part
2052 is 2 octets Local Administrator subfield.
2054 .. _bgp-extended-community-lists:
2056 Extended Community Lists
2057 ^^^^^^^^^^^^^^^^^^^^^^^^
2059 .. index:: bgp extcommunity-list standard NAME permit|deny EXTCOMMUNITY
2060 .. clicmd:: bgp extcommunity-list standard NAME permit|deny EXTCOMMUNITY
2062 This command defines a new standard extcommunity-list. `extcommunity` is
2063 extended communities value. The `extcommunity` is compiled into extended
2064 community structure. We can define multiple extcommunity-list under same
2065 name. In that case match will happen user defined order. Once the
2066 extcommunity-list matches to extended communities attribute in BGP updates
2067 it return permit or deny based upon the extcommunity-list definition. When
2068 there is no matched entry, deny will be returned. When `extcommunity` is
2069 empty it matches to any routes.
2071 .. index:: bgp extcommunity-list expanded NAME permit|deny LINE
2072 .. clicmd:: bgp extcommunity-list expanded NAME permit|deny LINE
2074 This command defines a new expanded extcommunity-list. `line` is a string
2075 expression of extended communities attribute. `line` can be a regular
2076 expression (:ref:`bgp-regular-expressions`) to match an extended communities
2077 attribute in BGP updates.
2079 .. index:: no bgp extcommunity-list NAME
2080 .. clicmd:: no bgp extcommunity-list NAME
2082 .. index:: no bgp extcommunity-list standard NAME
2083 .. clicmd:: no bgp extcommunity-list standard NAME
2085 .. index:: no bgp extcommunity-list expanded NAME
2086 .. clicmd:: no bgp extcommunity-list expanded NAME
2088 These commands delete extended community lists specified by `name`. All of
2089 extended community lists shares a single name space. So extended community
2090 lists can be removed simply specifying the name.
2092 .. index:: show bgp extcommunity-list
2093 .. clicmd:: show bgp extcommunity-list
2095 .. index:: show bgp extcommunity-list NAME detail
2096 .. clicmd:: show bgp extcommunity-list NAME detail
2098 This command displays current extcommunity-list information. When `name` is
2099 specified the community list's information is shown.::
2101 # show bgp extcommunity-list
2104 .. _bgp-extended-communities-in-route-map:
2106 BGP Extended Communities in Route Map
2107 """""""""""""""""""""""""""""""""""""
2109 .. index:: match extcommunity WORD
2110 .. clicmd:: match extcommunity WORD
2112 .. index:: set extcommunity rt EXTCOMMUNITY
2113 .. clicmd:: set extcommunity rt EXTCOMMUNITY
2115 This command set Route Target value.
2117 .. index:: set extcommunity soo EXTCOMMUNITY
2118 .. clicmd:: set extcommunity soo EXTCOMMUNITY
2120 This command set Site of Origin value.
2122 .. index:: set extcommunity bandwidth <(1-25600) | cumulative | num-multipaths> [non-transitive]
2123 .. clicmd:: set extcommunity bandwidth <(1-25600) | cumulative | num-multipaths> [non-transitive]
2125 This command sets the BGP link-bandwidth extended community for the prefix
2126 (best path) for which it is applied. The link-bandwidth can be specified as
2127 an ``explicit value`` (specified in Mbps), or the router can be told to use
2128 the ``cumulative bandwidth`` of all multipaths for the prefix or to compute
2129 it based on the ``number of multipaths``. The link bandwidth extended
2130 community is encoded as ``transitive`` unless the set command explicitly
2131 configures it as ``non-transitive``.
2133 .. seealso:: :ref:`wecmp_linkbw`
2135 Note that the extended expanded community is only used for `match` rule, not for
2138 .. _bgp-large-communities-attribute:
2140 Large Communities Attribute
2141 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
2143 The BGP Large Communities attribute was introduced in Feb 2017 with
2146 The BGP Large Communities Attribute is similar to the BGP Communities Attribute
2147 except that it has 3 components instead of two and each of which are 4 octets
2148 in length. Large Communities bring additional functionality and convenience
2149 over traditional communities, specifically the fact that the ``GLOBAL`` part
2150 below is now 4 octets wide allowing seamless use in networks using 4-byte ASNs.
2152 ``GLOBAL:LOCAL1:LOCAL2``
2153 This is the format to define Large Community values. Referencing :rfc:`8195`
2154 the values are commonly referred to as follows:
2156 - The ``GLOBAL`` part is a 4 octet Global Administrator field, commonly used
2157 as the operators AS number.
2158 - The ``LOCAL1`` part is a 4 octet Local Data Part 1 subfield referred to as
2160 - The ``LOCAL2`` part is a 4 octet Local Data Part 2 field and referred to
2161 as the parameter subfield.
2163 As an example, ``65551:1:10`` represents AS 65551 function 1 and parameter
2164 10. The referenced RFC above gives some guidelines on recommended usage.
2166 .. _bgp-large-community-lists:
2168 Large Community Lists
2169 """""""""""""""""""""
2171 Two types of large community lists are supported, namely `standard` and
2174 .. index:: bgp large-community-list standard NAME permit|deny LARGE-COMMUNITY
2175 .. clicmd:: bgp large-community-list standard NAME permit|deny LARGE-COMMUNITY
2177 This command defines a new standard large-community-list. `large-community`
2178 is the Large Community value. We can add multiple large communities under
2179 same name. In that case the match will happen in the user defined order.
2180 Once the large-community-list matches the Large Communities attribute in BGP
2181 updates it will return permit or deny based upon the large-community-list
2182 definition. When there is no matched entry, a deny will be returned. When
2183 `large-community` is empty it matches any routes.
2185 .. index:: bgp large-community-list expanded NAME permit|deny LINE
2186 .. clicmd:: bgp large-community-list expanded NAME permit|deny LINE
2188 This command defines a new expanded large-community-list. Where `line` is a
2189 string matching expression, it will be compared to the entire Large
2190 Communities attribute as a string, with each large-community in order from
2191 lowest to highest. `line` can also be a regular expression which matches
2192 this Large Community attribute.
2194 .. index:: no bgp large-community-list NAME
2195 .. clicmd:: no bgp large-community-list NAME
2197 .. index:: no bgp large-community-list standard NAME
2198 .. clicmd:: no bgp large-community-list standard NAME
2200 .. index:: no bgp large-community-list expanded NAME
2201 .. clicmd:: no bgp large-community-list expanded NAME
2203 These commands delete Large Community lists specified by `name`. All Large
2204 Community lists share a single namespace. This means Large Community lists
2205 can be removed by simply specifying the name.
2207 .. index:: show bgp large-community-list
2208 .. clicmd:: show bgp large-community-list
2210 .. index:: show bgp large-community-list NAME detail
2211 .. clicmd:: show bgp large-community-list NAME detail
2213 This command display current large-community-list information. When
2214 `name` is specified the community list information is shown.
2216 .. index:: show ip bgp large-community-info
2217 .. clicmd:: show ip bgp large-community-info
2219 This command displays the current large communities in use.
2221 .. _bgp-large-communities-in-route-map:
2223 Large Communities in Route Map
2224 """"""""""""""""""""""""""""""
2226 .. index:: match large-community LINE [exact-match]
2227 .. clicmd:: match large-community LINE [exact-match]
2229 Where `line` can be a simple string to match, or a regular expression. It
2230 is very important to note that this match occurs on the entire
2231 large-community string as a whole, where each large-community is ordered
2232 from lowest to highest. When `exact-match` keyword is specified, match
2233 happen only when BGP updates have completely same large communities value
2234 specified in the large community list.
2236 .. index:: set large-community LARGE-COMMUNITY
2237 .. clicmd:: set large-community LARGE-COMMUNITY
2239 .. index:: set large-community LARGE-COMMUNITY LARGE-COMMUNITY
2240 .. clicmd:: set large-community LARGE-COMMUNITY LARGE-COMMUNITY
2242 .. index:: set large-community LARGE-COMMUNITY additive
2243 .. clicmd:: set large-community LARGE-COMMUNITY additive
2245 These commands are used for setting large-community values. The first
2246 command will overwrite any large-communities currently present.
2247 The second specifies two large-communities, which overwrites the current
2248 large-community list. The third will add a large-community value without
2249 overwriting other values. Multiple large-community values can be specified.
2251 Note that the large expanded community is only used for `match` rule, not for
2259 *bgpd* supports :abbr:`L3VPN (Layer 3 Virtual Private Networks)` :abbr:`VRFs
2260 (Virtual Routing and Forwarding)` for IPv4 :rfc:`4364` and IPv6 :rfc:`4659`.
2261 L3VPN routes, and their associated VRF MPLS labels, can be distributed to VPN
2262 SAFI neighbors in the *default*, i.e., non VRF, BGP instance. VRF MPLS labels
2263 are reached using *core* MPLS labels which are distributed using LDP or BGP
2264 labeled unicast. *bgpd* also supports inter-VRF route leaking.
2267 .. _bgp-vrf-route-leaking:
2272 BGP routes may be leaked (i.e. copied) between a unicast VRF RIB and the VPN
2273 SAFI RIB of the default VRF for use in MPLS-based L3VPNs. Unicast routes may
2274 also be leaked between any VRFs (including the unicast RIB of the default BGP
2275 instanced). A shortcut syntax is also available for specifying leaking from one
2276 VRF to another VRF using the default instance's VPN RIB as the intemediary. A
2277 common application of the VRF-VRF feature is to connect a customer's private
2278 routing domain to a provider's VPN service. Leaking is configured from the
2279 point of view of an individual VRF: ``import`` refers to routes leaked from VPN
2280 to a unicast VRF, whereas ``export`` refers to routes leaked from a unicast VRF
2286 Routes exported from a unicast VRF to the VPN RIB must be augmented by two
2289 - an :abbr:`RD (Route Distinguisher)`
2290 - an :abbr:`RTLIST (Route-target List)`
2292 Configuration for these exported routes must, at a minimum, specify these two
2295 Routes imported from the VPN RIB to a unicast VRF are selected according to
2296 their RTLISTs. Routes whose RTLIST contains at least one route-target in
2297 common with the configured import RTLIST are leaked. Configuration for these
2298 imported routes must specify an RTLIST to be matched.
2300 The RD, which carries no semantic value, is intended to make the route unique
2301 in the VPN RIB among all routes of its prefix that originate from all the
2302 customers and sites that are attached to the provider's VPN service.
2303 Accordingly, each site of each customer is typically assigned an RD that is
2304 unique across the entire provider network.
2306 The RTLIST is a set of route-target extended community values whose purpose is
2307 to specify route-leaking policy. Typically, a customer is assigned a single
2308 route-target value for import and export to be used at all customer sites. This
2309 configuration specifies a simple topology wherein a customer has a single
2310 routing domain which is shared across all its sites. More complex routing
2311 topologies are possible through use of additional route-targets to augment the
2312 leaking of sets of routes in various ways.
2314 When using the shortcut syntax for vrf-to-vrf leaking, the RD and RT are
2317 General configuration
2318 ^^^^^^^^^^^^^^^^^^^^^
2320 Configuration of route leaking between a unicast VRF RIB and the VPN SAFI RIB
2321 of the default VRF is accomplished via commands in the context of a VRF
2324 .. index:: rd vpn export AS:NN|IP:nn
2325 .. clicmd:: rd vpn export AS:NN|IP:nn
2327 Specifies the route distinguisher to be added to a route exported from the
2328 current unicast VRF to VPN.
2330 .. index:: no rd vpn export [AS:NN|IP:nn]
2331 .. clicmd:: no rd vpn export [AS:NN|IP:nn]
2333 Deletes any previously-configured export route distinguisher.
2335 .. index:: rt vpn import|export|both RTLIST...
2336 .. clicmd:: rt vpn import|export|both RTLIST...
2338 Specifies the route-target list to be attached to a route (export) or the
2339 route-target list to match against (import) when exporting/importing between
2340 the current unicast VRF and VPN.
2342 The RTLIST is a space-separated list of route-targets, which are BGP
2343 extended community values as described in
2344 :ref:`bgp-extended-communities-attribute`.
2346 .. index:: no rt vpn import|export|both [RTLIST...]
2347 .. clicmd:: no rt vpn import|export|both [RTLIST...]
2349 Deletes any previously-configured import or export route-target list.
2351 .. index:: label vpn export (0..1048575)|auto
2352 .. clicmd:: label vpn export (0..1048575)|auto
2354 Enables an MPLS label to be attached to a route exported from the current
2355 unicast VRF to VPN. If the value specified is ``auto``, the label value is
2356 automatically assigned from a pool maintained by the Zebra daemon. If Zebra
2357 is not running, or if this command is not configured, automatic label
2358 assignment will not complete, which will block corresponding route export.
2360 .. index:: no label vpn export [(0..1048575)|auto]
2361 .. clicmd:: no label vpn export [(0..1048575)|auto]
2363 Deletes any previously-configured export label.
2365 .. index:: nexthop vpn export A.B.C.D|X:X::X:X
2366 .. clicmd:: nexthop vpn export A.B.C.D|X:X::X:X
2368 Specifies an optional nexthop value to be assigned to a route exported from
2369 the current unicast VRF to VPN. If left unspecified, the nexthop will be set
2370 to 0.0.0.0 or 0:0::0:0 (self).
2372 .. index:: no nexthop vpn export [A.B.C.D|X:X::X:X]
2373 .. clicmd:: no nexthop vpn export [A.B.C.D|X:X::X:X]
2375 Deletes any previously-configured export nexthop.
2377 .. index:: route-map vpn import|export MAP
2378 .. clicmd:: route-map vpn import|export MAP
2380 Specifies an optional route-map to be applied to routes imported or exported
2381 between the current unicast VRF and VPN.
2383 .. index:: no route-map vpn import|export [MAP]
2384 .. clicmd:: no route-map vpn import|export [MAP]
2386 Deletes any previously-configured import or export route-map.
2388 .. index:: import|export vpn
2389 .. clicmd:: import|export vpn
2391 Enables import or export of routes between the current unicast VRF and VPN.
2393 .. index:: no import|export vpn
2394 .. clicmd:: no import|export vpn
2396 Disables import or export of routes between the current unicast VRF and VPN.
2398 .. index:: import vrf VRFNAME
2399 .. clicmd:: import vrf VRFNAME
2401 Shortcut syntax for specifying automatic leaking from vrf VRFNAME to
2402 the current VRF using the VPN RIB as intermediary. The RD and RT
2403 are auto derived and should not be specified explicitly for either the
2404 source or destination VRF's.
2406 This shortcut syntax mode is not compatible with the explicit
2407 `import vpn` and `export vpn` statements for the two VRF's involved.
2408 The CLI will disallow attempts to configure incompatible leaking
2411 .. index:: no import vrf VRFNAME
2412 .. clicmd:: no import vrf VRFNAME
2414 Disables automatic leaking from vrf VRFNAME to the current VRF using
2415 the VPN RIB as intermediary.
2420 Ethernet Virtual Network - EVPN
2421 -------------------------------
2423 .. _bgp-evpn-advertise-pip:
2428 In a EVPN symmetric routing MLAG deployment, all EVPN routes advertised
2429 with anycast-IP as next-hop IP and anycast MAC as the Router MAC (RMAC - in
2430 BGP EVPN Extended-Community).
2431 EVPN picks up the next-hop IP from the VxLAN interface's local tunnel IP and
2432 the RMAC is obtained from the MAC of the L3VNI's SVI interface.
2433 Note: Next-hop IP is used for EVPN routes whether symmetric routing is
2434 deployed or not but the RMAC is only relevant for symmetric routing scenario.
2436 Current behavior is not ideal for Prefix (type-5) and self (type-2)
2437 routes. This is because the traffic from remote VTEPs routed sub optimally
2438 if they land on the system where the route does not belong.
2440 The advertise-pip feature advertises Prefix (type-5) and self (type-2)
2441 routes with system's individual (primary) IP as the next-hop and individual
2442 (system) MAC as Router-MAC (RMAC), while leaving the behavior unchanged for
2445 To support this feature there needs to have ability to co-exist a
2446 (system-MAC, system-IP) pair with a (anycast-MAC, anycast-IP) pair with the
2447 ability to terminate VxLAN-encapsulated packets received for either pair on
2448 the same L3VNI (i.e associated VLAN). This capability is need per tenant
2451 To derive the system-MAC and the anycast MAC, there needs to have a
2452 separate/additional MAC-VLAN interface corresponding to L3VNI’s SVI.
2453 The SVI interface’s MAC address can be interpreted as system-MAC
2454 and MAC-VLAN interface's MAC as anycast MAC.
2456 To derive system-IP and anycast-IP, the default BGP instance's router-id is used
2457 as system-IP and the VxLAN interface’s local tunnel IP as the anycast-IP.
2459 User has an option to configure the system-IP and/or system-MAC value if the
2460 auto derived value is not preferred.
2462 Note: By default, advertise-pip feature is enabled and user has an option to
2463 disable the feature via configuration CLI. Once the feature is disable under
2464 bgp vrf instance or MAC-VLAN interface is not configured, all the routes follow
2465 the same behavior of using same next-hop and RMAC values.
2467 .. index:: [no] advertise-pip [ip <addr> [mac <addr>]]
2468 .. clicmd:: [no] advertise-pip [ip <addr> [mac <addr>]]
2470 Enables or disables advertise-pip feature, specifiy system-IP and/or system-MAC
2479 .. index:: show debug
2480 .. clicmd:: show debug
2482 Show all enabled debugs.
2484 .. index:: show bgp listeners
2485 .. clicmd:: show bgp listeners
2487 Display Listen sockets and the vrf that created them. Useful for debugging of when
2488 listen is not working and this is considered a developer debug statement.
2490 .. index:: [no] debug bgp neighbor-events
2491 .. clicmd:: [no] debug bgp neighbor-events
2493 Enable or disable debugging for neighbor events. This provides general
2494 information on BGP events such as peer connection / disconnection, session
2495 establishment / teardown, and capability negotiation.
2497 .. index:: [no] debug bgp updates
2498 .. clicmd:: [no] debug bgp updates
2500 Enable or disable debugging for BGP updates. This provides information on
2501 BGP UPDATE messages transmitted and received between local and remote
2504 .. index:: [no] debug bgp keepalives
2505 .. clicmd:: [no] debug bgp keepalives
2507 Enable or disable debugging for BGP keepalives. This provides information on
2508 BGP KEEPALIVE messages transmitted and received between local and remote
2511 .. index:: [no] debug bgp bestpath <A.B.C.D/M|X:X::X:X/M>
2512 .. clicmd:: [no] debug bgp bestpath <A.B.C.D/M|X:X::X:X/M>
2514 Enable or disable debugging for bestpath selection on the specified prefix.
2516 .. index:: [no] debug bgp nht
2517 .. clicmd:: [no] debug bgp nht
2519 Enable or disable debugging of BGP nexthop tracking.
2521 .. index:: [no] debug bgp update-groups
2522 .. clicmd:: [no] debug bgp update-groups
2524 Enable or disable debugging of dynamic update groups. This provides general
2525 information on group creation, deletion, join and prune events.
2527 .. index:: [no] debug bgp zebra
2528 .. clicmd:: [no] debug bgp zebra
2530 Enable or disable debugging of communications between *bgpd* and *zebra*.
2532 Dumping Messages and Routing Tables
2533 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2535 .. index:: dump bgp all PATH [INTERVAL]
2536 .. clicmd:: dump bgp all PATH [INTERVAL]
2538 .. index:: dump bgp all-et PATH [INTERVAL]
2539 .. clicmd:: dump bgp all-et PATH [INTERVAL]
2541 .. index:: no dump bgp all [PATH] [INTERVAL]
2542 .. clicmd:: no dump bgp all [PATH] [INTERVAL]
2544 Dump all BGP packet and events to `path` file.
2545 If `interval` is set, a new file will be created for echo `interval` of
2546 seconds. The path `path` can be set with date and time formatting
2547 (strftime). The type ‘all-et’ enables support for Extended Timestamp Header
2548 (:ref:`packet-binary-dump-format`).
2550 .. index:: dump bgp updates PATH [INTERVAL]
2551 .. clicmd:: dump bgp updates PATH [INTERVAL]
2553 .. index:: dump bgp updates-et PATH [INTERVAL]
2554 .. clicmd:: dump bgp updates-et PATH [INTERVAL]
2556 .. index:: no dump bgp updates [PATH] [INTERVAL]
2557 .. clicmd:: no dump bgp updates [PATH] [INTERVAL]
2559 Dump only BGP updates messages to `path` file.
2560 If `interval` is set, a new file will be created for echo `interval` of
2561 seconds. The path `path` can be set with date and time formatting
2562 (strftime). The type ‘updates-et’ enables support for Extended Timestamp
2563 Header (:ref:`packet-binary-dump-format`).
2565 .. index:: dump bgp routes-mrt PATH
2566 .. clicmd:: dump bgp routes-mrt PATH
2568 .. index:: dump bgp routes-mrt PATH INTERVAL
2569 .. clicmd:: dump bgp routes-mrt PATH INTERVAL
2571 .. index:: no dump bgp route-mrt [PATH] [INTERVAL]
2572 .. clicmd:: no dump bgp route-mrt [PATH] [INTERVAL]
2574 Dump whole BGP routing table to `path`. This is heavy process. The path
2575 `path` can be set with date and time formatting (strftime). If `interval` is
2576 set, a new file will be created for echo `interval` of seconds.
2578 Note: the interval variable can also be set using hours and minutes: 04h20m00.
2581 .. _bgp-other-commands:
2586 The following are available in the top level *enable* mode:
2588 .. index:: clear bgp \*
2589 .. clicmd:: clear bgp \*
2593 .. index:: clear bgp ipv4|ipv6 \*
2594 .. clicmd:: clear bgp ipv4|ipv6 \*
2596 Clear all peers with this address-family activated.
2598 .. index:: clear bgp ipv4|ipv6 unicast \*
2599 .. clicmd:: clear bgp ipv4|ipv6 unicast \*
2601 Clear all peers with this address-family and sub-address-family activated.
2603 .. index:: clear bgp ipv4|ipv6 PEER
2604 .. clicmd:: clear bgp ipv4|ipv6 PEER
2606 Clear peers with address of X.X.X.X and this address-family activated.
2608 .. index:: clear bgp ipv4|ipv6 unicast PEER
2609 .. clicmd:: clear bgp ipv4|ipv6 unicast PEER
2611 Clear peer with address of X.X.X.X and this address-family and sub-address-family activated.
2613 .. index:: clear bgp ipv4|ipv6 PEER soft|in|out
2614 .. clicmd:: clear bgp ipv4|ipv6 PEER soft|in|out
2616 Clear peer using soft reconfiguration in this address-family.
2618 .. index:: clear bgp ipv4|ipv6 unicast PEER soft|in|out
2619 .. clicmd:: clear bgp ipv4|ipv6 unicast PEER soft|in|out
2621 Clear peer using soft reconfiguration in this address-family and sub-address-family.
2623 The following are available in the ``router bgp`` mode:
2625 .. index:: write-quanta (1-64)
2626 .. clicmd:: write-quanta (1-64)
2628 BGP message Tx I/O is vectored. This means that multiple packets are written
2629 to the peer socket at the same time each I/O cycle, in order to minimize
2630 system call overhead. This value controls how many are written at a time.
2631 Under certain load conditions, reducing this value could make peer traffic
2632 less 'bursty'. In practice, leave this settings on the default (64) unless
2633 you truly know what you are doing.
2635 .. index:: read-quanta (1-10)
2636 .. clicmd:: read-quanta (1-10)
2638 Unlike Tx, BGP Rx traffic is not vectored. Packets are read off the wire one
2639 at a time in a loop. This setting controls how many iterations the loop runs
2640 for. As with write-quanta, it is best to leave this setting on the default.
2642 .. _bgp-displaying-bgp-information:
2644 Displaying BGP Information
2645 ==========================
2647 The following four commands display the IPv6 and IPv4 routing tables, depending
2648 on whether or not the ``ip`` keyword is used.
2649 Actually, :clicmd:`show ip bgp` command was used on older `Quagga` routing
2650 daemon project, while :clicmd:`show bgp` command is the new format. The choice
2651 has been done to keep old format with IPv4 routing table, while new format
2652 displays IPv6 routing table.
2654 .. index:: show ip bgp [wide]
2655 .. clicmd:: show ip bgp [wide]
2657 .. index:: show ip bgp A.B.C.D [wide]
2658 .. clicmd:: show ip bgp A.B.C.D [wide]
2660 .. index:: show bgp [wide]
2661 .. clicmd:: show bgp [wide]
2663 .. index:: show bgp X:X::X:X [wide]
2664 .. clicmd:: show bgp X:X::X:X [wide]
2666 These commands display BGP routes. When no route is specified, the default
2667 is to display all BGP routes.
2671 BGP table version is 0, local router ID is 10.1.1.1
2672 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
2673 Origin codes: i - IGP, e - EGP, ? - incomplete
2675 Network Next Hop Metric LocPrf Weight Path
2676 \*> 1.1.1.1/32 0.0.0.0 0 32768 i
2678 Total number of prefixes 1
2680 If _wide_ option is specified, then the prefix table's width is increased
2681 to fully display the prefix and the nexthop.
2683 This is especially handy dealing with IPv6 prefixes and
2684 if :clicmd:`[no] bgp default show-nexthop-hostname` is enabled.
2686 Some other commands provide additional options for filtering the output.
2688 .. index:: show [ip] bgp regexp LINE
2689 .. clicmd:: show [ip] bgp regexp LINE
2691 This command displays BGP routes using AS path regular expression
2692 (:ref:`bgp-regular-expressions`).
2694 .. index:: show [ip] bgp summary
2695 .. clicmd:: show [ip] bgp summary
2697 Show a bgp peer summary for the specified address family.
2699 The old command structure :clicmd:`show ip bgp` may be removed in the future
2700 and should no longer be used. In order to reach the other BGP routing tables
2701 other than the IPv6 routing table given by :clicmd:`show bgp`, the new command
2702 structure is extended with :clicmd:`show bgp [afi] [safi]`.
2704 .. index:: show bgp [afi] [safi]
2705 .. clicmd:: show bgp [afi] [safi]
2707 .. index:: show bgp <ipv4|ipv6> <unicast|multicast|vpn|labeled-unicast>
2708 .. clicmd:: show bgp <ipv4|ipv6> <unicast|multicast|vpn|labeled-unicast>
2710 These commands display BGP routes for the specific routing table indicated by
2711 the selected afi and the selected safi. If no afi and no safi value is given,
2712 the command falls back to the default IPv6 routing table.
2713 For EVPN prefixes, you can display the full BGP table for this AFI/SAFI
2714 using the standard `show bgp [afi] [safi]` syntax.
2716 .. index:: show bgp l2vpn evpn route [type <macip|2|multicast|3|es|4|prefix|5>]
2717 .. clicmd:: show bgp l2vpn evpn route [type <macip|2|multicast|3|es|4|prefix|5>]
2719 Additionally, you can also filter this output by route type.
2721 .. index:: show bgp [afi] [safi] summary
2722 .. clicmd:: show bgp [afi] [safi] summary
2724 Show a bgp peer summary for the specified address family, and subsequent
2727 .. index:: show bgp [afi] [safi] summary failed [json]
2728 .. clicmd:: show bgp [afi] [safi] summary failed [json]
2730 Show a bgp peer summary for peers that are not succesfully exchanging routes
2731 for the specified address family, and subsequent address-family.
2733 .. index:: show bgp [afi] [safi] summary established [json]
2734 .. clicmd:: show bgp [afi] [safi] summary established [json]
2736 Show a bgp peer summary for peers that are succesfully exchanging routes
2737 for the specified address family, and subsequent address-family.
2739 .. index:: show bgp [afi] [safi] neighbor [PEER]
2740 .. clicmd:: show bgp [afi] [safi] neighbor [PEER]
2742 This command shows information on a specific BGP peer of the relevant
2743 afi and safi selected.
2745 .. index:: show bgp [afi] [safi] dampening dampened-paths
2746 .. clicmd:: show bgp [afi] [safi] dampening dampened-paths
2748 Display paths suppressed due to dampening of the selected afi and safi
2751 .. index:: show bgp [afi] [safi] dampening flap-statistics
2752 .. clicmd:: show bgp [afi] [safi] dampening flap-statistics
2754 Display flap statistics of routes of the selected afi and safi selected.
2756 .. index:: show bgp [afi] [safi] statistics
2757 .. clicmd:: show bgp [afi] [safi] statistics
2759 Display statistics of routes of the selected afi and safi.
2761 .. index:: show bgp statistics-all
2762 .. clicmd:: show bgp statistics-all
2764 Display statistics of routes of all the afi and safi.
2766 .. _bgp-display-routes-by-community:
2768 Displaying Routes by Community Attribute
2769 ----------------------------------------
2771 The following commands allow displaying routes based on their community
2774 .. index:: show [ip] bgp <ipv4|ipv6> community
2775 .. clicmd:: show [ip] bgp <ipv4|ipv6> community
2777 .. index:: show [ip] bgp <ipv4|ipv6> community COMMUNITY
2778 .. clicmd:: show [ip] bgp <ipv4|ipv6> community COMMUNITY
2780 .. index:: show [ip] bgp <ipv4|ipv6> community COMMUNITY exact-match
2781 .. clicmd:: show [ip] bgp <ipv4|ipv6> community COMMUNITY exact-match
2783 These commands display BGP routes which have the community attribute.
2784 attribute. When ``COMMUNITY`` is specified, BGP routes that match that
2785 community are displayed. When `exact-match` is specified, it display only
2786 routes that have an exact match.
2788 .. index:: show [ip] bgp <ipv4|ipv6> community-list WORD
2789 .. clicmd:: show [ip] bgp <ipv4|ipv6> community-list WORD
2791 .. index:: show [ip] bgp <ipv4|ipv6> community-list WORD exact-match
2792 .. clicmd:: show [ip] bgp <ipv4|ipv6> community-list WORD exact-match
2794 These commands display BGP routes for the address family specified that
2795 match the specified community list. When `exact-match` is specified, it
2796 displays only routes that have an exact match.
2798 .. _bgp-display-routes-by-lcommunity:
2800 Displaying Routes by Large Community Attribute
2801 ----------------------------------------------
2803 The following commands allow displaying routes based on their
2804 large community attribute.
2806 .. index:: show [ip] bgp <ipv4|ipv6> large-community
2807 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community
2809 .. index:: show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY
2810 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY
2812 .. index:: show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY exact-match
2813 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY exact-match
2815 .. index:: show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY json
2816 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community LARGE-COMMUNITY json
2818 These commands display BGP routes which have the large community attribute.
2819 attribute. When ``LARGE-COMMUNITY`` is specified, BGP routes that match that
2820 large community are displayed. When `exact-match` is specified, it display
2821 only routes that have an exact match. When `json` is specified, it display
2822 routes in json format.
2824 .. index:: show [ip] bgp <ipv4|ipv6> large-community-list WORD
2825 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community-list WORD
2827 .. index:: show [ip] bgp <ipv4|ipv6> large-community-list WORD exact-match
2828 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community-list WORD exact-match
2830 .. index:: show [ip] bgp <ipv4|ipv6> large-community-list WORD json
2831 .. clicmd:: show [ip] bgp <ipv4|ipv6> large-community-list WORD json
2833 These commands display BGP routes for the address family specified that
2834 match the specified large community list. When `exact-match` is specified,
2835 it displays only routes that have an exact match. When `json` is specified,
2836 it display routes in json format.
2838 .. _bgp-display-routes-by-as-path:
2841 Displaying Routes by AS Path
2842 ----------------------------
2844 .. index:: show bgp ipv4|ipv6 regexp LINE
2845 .. clicmd:: show bgp ipv4|ipv6 regexp LINE
2847 This commands displays BGP routes that matches a regular
2848 expression `line` (:ref:`bgp-regular-expressions`).
2850 .. index:: show [ip] bgp ipv4 vpn
2851 .. clicmd:: show [ip] bgp ipv4 vpn
2853 .. index:: show [ip] bgp ipv6 vpn
2854 .. clicmd:: show [ip] bgp ipv6 vpn
2856 Print active IPV4 or IPV6 routes advertised via the VPN SAFI.
2858 .. index:: show bgp ipv4 vpn summary
2859 .. clicmd:: show bgp ipv4 vpn summary
2861 .. index:: show bgp ipv6 vpn summary
2862 .. clicmd:: show bgp ipv6 vpn summary
2864 Print a summary of neighbor connections for the specified AFI/SAFI combination.
2866 Displaying Update Group Information
2867 -----------------------------------
2869 .. index:: show bgp update-groups SUBGROUP-ID [advertise-queue|advertised-routes|packet-queue]
2870 .. clicmd:: show bgp update-groups [advertise-queue|advertised-routes|packet-queue]
2872 Display Information about each individual update-group being used.
2873 If SUBGROUP-ID is specified only display about that particular group. If
2874 advertise-queue is specified the list of routes that need to be sent
2875 to the peers in the update-group is displayed, advertised-routes means
2876 the list of routes we have sent to the peers in the update-group and
2877 packet-queue specifies the list of packets in the queue to be sent.
2879 .. index:: show bgp update-groups statistics
2880 .. clicmd:: show bgp update-groups statistics
2882 Display Information about update-group events in FRR.
2884 .. _bgp-route-reflector:
2889 BGP routers connected inside the same AS through BGP belong to an internal
2890 BGP session, or IBGP. In order to prevent routing table loops, IBGP does not
2891 advertise IBGP-learned routes to other routers in the same session. As such,
2892 IBGP requires a full mesh of all peers. For large networks, this quickly becomes
2893 unscalable. Introducing route reflectors removes the need for the full-mesh.
2895 When route reflectors are configured, these will reflect the routes announced
2896 by the peers configured as clients. A route reflector client is configured
2899 .. index:: neighbor PEER route-reflector-client
2900 .. clicmd:: neighbor PEER route-reflector-client
2902 .. index:: no neighbor PEER route-reflector-client
2903 .. clicmd:: no neighbor PEER route-reflector-client
2905 To avoid single points of failure, multiple route reflectors can be configured.
2907 A cluster is a collection of route reflectors and their clients, and is used
2908 by route reflectors to avoid looping.
2910 .. index:: bgp cluster-id A.B.C.D
2911 .. clicmd:: bgp cluster-id A.B.C.D
2918 You can set different routing policy for a peer. For example, you can set
2919 different filter for a peer.
2925 neighbor 10.0.0.1 remote-as 2
2926 address-family ipv4 unicast
2927 neighbor 10.0.0.1 distribute-list 1 in
2931 neighbor 10.0.0.1 remote-as 2
2932 address-family ipv4 unicast
2933 neighbor 10.0.0.1 distribute-list 2 in
2936 This means BGP update from a peer 10.0.0.1 goes to both BGP view 1 and view 2.
2937 When the update is inserted into view 1, distribute-list 1 is applied. On the
2938 other hand, when the update is inserted into view 2, distribute-list 2 is
2942 .. _bgp-regular-expressions:
2944 BGP Regular Expressions
2945 =======================
2947 BGP regular expressions are based on :t:`POSIX 1003.2` regular expressions. The
2948 following description is just a quick subset of the POSIX regular expressions.
2952 Matches any single character.
2955 Matches 0 or more occurrences of pattern.
2958 Matches 1 or more occurrences of pattern.
2961 Match 0 or 1 occurrences of pattern.
2964 Matches the beginning of the line.
2967 Matches the end of the line.
2970 The ``_`` character has special meanings in BGP regular expressions. It
2971 matches to space and comma , and AS set delimiter ``{`` and ``}`` and AS
2972 confederation delimiter ``(`` and ``)``. And it also matches to the
2973 beginning of the line and the end of the line. So ``_`` can be used for AS
2974 value boundaries match. This character technically evaluates to
2978 .. _bgp-configuration-examples:
2980 Miscellaneous Configuration Examples
2981 ====================================
2983 Example of a session to an upstream, advertising only one prefix to it.
2988 bgp router-id 10.236.87.1
2989 neighbor upstream peer-group
2990 neighbor upstream remote-as 64515
2991 neighbor upstream capability dynamic
2992 neighbor 10.1.1.1 peer-group upstream
2993 neighbor 10.1.1.1 description ACME ISP
2995 address-family ipv4 unicast
2996 network 10.236.87.0/24
2997 neighbor upstream prefix-list pl-allowed-adv out
3000 ip prefix-list pl-allowed-adv seq 5 permit 82.195.133.0/25
3001 ip prefix-list pl-allowed-adv seq 10 deny any
3003 A more complex example including upstream, peer and customer sessions
3004 advertising global prefixes and NO_EXPORT prefixes and providing actions for
3005 customer routes based on community values. Extensive use is made of route-maps
3006 and the 'call' feature to support selective advertising of prefixes. This
3007 example is intended as guidance only, it has NOT been tested and almost
3008 certainly contains silly mistakes, if not serious flaws.
3013 bgp router-id 10.236.87.1
3014 neighbor upstream capability dynamic
3015 neighbor cust capability dynamic
3016 neighbor peer capability dynamic
3017 neighbor 10.1.1.1 remote-as 64515
3018 neighbor 10.1.1.1 peer-group upstream
3019 neighbor 10.2.1.1 remote-as 64516
3020 neighbor 10.2.1.1 peer-group upstream
3021 neighbor 10.3.1.1 remote-as 64517
3022 neighbor 10.3.1.1 peer-group cust-default
3023 neighbor 10.3.1.1 description customer1
3024 neighbor 10.4.1.1 remote-as 64518
3025 neighbor 10.4.1.1 peer-group cust
3026 neighbor 10.4.1.1 description customer2
3027 neighbor 10.5.1.1 remote-as 64519
3028 neighbor 10.5.1.1 peer-group peer
3029 neighbor 10.5.1.1 description peer AS 1
3030 neighbor 10.6.1.1 remote-as 64520
3031 neighbor 10.6.1.1 peer-group peer
3032 neighbor 10.6.1.1 description peer AS 2
3034 address-family ipv4 unicast
3035 network 10.123.456.0/24
3036 network 10.123.456.128/25 route-map rm-no-export
3037 neighbor upstream route-map rm-upstream-out out
3038 neighbor cust route-map rm-cust-in in
3039 neighbor cust route-map rm-cust-out out
3040 neighbor cust send-community both
3041 neighbor peer route-map rm-peer-in in
3042 neighbor peer route-map rm-peer-out out
3043 neighbor peer send-community both
3044 neighbor 10.3.1.1 prefix-list pl-cust1-network in
3045 neighbor 10.4.1.1 prefix-list pl-cust2-network in
3046 neighbor 10.5.1.1 prefix-list pl-peer1-network in
3047 neighbor 10.6.1.1 prefix-list pl-peer2-network in
3050 ip prefix-list pl-default permit 0.0.0.0/0
3052 ip prefix-list pl-upstream-peers permit 10.1.1.1/32
3053 ip prefix-list pl-upstream-peers permit 10.2.1.1/32
3055 ip prefix-list pl-cust1-network permit 10.3.1.0/24
3056 ip prefix-list pl-cust1-network permit 10.3.2.0/24
3058 ip prefix-list pl-cust2-network permit 10.4.1.0/24
3060 ip prefix-list pl-peer1-network permit 10.5.1.0/24
3061 ip prefix-list pl-peer1-network permit 10.5.2.0/24
3062 ip prefix-list pl-peer1-network permit 192.168.0.0/24
3064 ip prefix-list pl-peer2-network permit 10.6.1.0/24
3065 ip prefix-list pl-peer2-network permit 10.6.2.0/24
3066 ip prefix-list pl-peer2-network permit 192.168.1.0/24
3067 ip prefix-list pl-peer2-network permit 192.168.2.0/24
3068 ip prefix-list pl-peer2-network permit 172.16.1/24
3070 bgp as-path access-list asp-own-as permit ^$
3071 bgp as-path access-list asp-own-as permit _64512_
3073 ! #################################################################
3074 ! Match communities we provide actions for, on routes receives from
3075 ! customers. Communities values of <our-ASN>:X, with X, have actions:
3077 ! 100 - blackhole the prefix
3078 ! 200 - set no_export
3079 ! 300 - advertise only to other customers
3080 ! 400 - advertise only to upstreams
3081 ! 500 - set no_export when advertising to upstreams
3082 ! 2X00 - set local_preference to X00
3084 ! blackhole the prefix of the route
3085 bgp community-list standard cm-blackhole permit 64512:100
3087 ! set no-export community before advertising
3088 bgp community-list standard cm-set-no-export permit 64512:200
3090 ! advertise only to other customers
3091 bgp community-list standard cm-cust-only permit 64512:300
3093 ! advertise only to upstreams
3094 bgp community-list standard cm-upstream-only permit 64512:400
3096 ! advertise to upstreams with no-export
3097 bgp community-list standard cm-upstream-noexport permit 64512:500
3099 ! set local-pref to least significant 3 digits of the community
3100 bgp community-list standard cm-prefmod-100 permit 64512:2100
3101 bgp community-list standard cm-prefmod-200 permit 64512:2200
3102 bgp community-list standard cm-prefmod-300 permit 64512:2300
3103 bgp community-list standard cm-prefmod-400 permit 64512:2400
3104 bgp community-list expanded cme-prefmod-range permit 64512:2...
3106 ! Informational communities
3108 ! 3000 - learned from upstream
3109 ! 3100 - learned from customer
3110 ! 3200 - learned from peer
3112 bgp community-list standard cm-learnt-upstream permit 64512:3000
3113 bgp community-list standard cm-learnt-cust permit 64512:3100
3114 bgp community-list standard cm-learnt-peer permit 64512:3200
3116 ! ###################################################################
3117 ! Utility route-maps
3119 ! These utility route-maps generally should not used to permit/deny
3120 ! routes, i.e. they do not have meaning as filters, and hence probably
3121 ! should be used with 'on-match next'. These all finish with an empty
3122 ! permit entry so as not interfere with processing in the caller.
3124 route-map rm-no-export permit 10
3125 set community additive no-export
3126 route-map rm-no-export permit 20
3128 route-map rm-blackhole permit 10
3129 description blackhole, up-pref and ensure it cannot escape this AS
3130 set ip next-hop 127.0.0.1
3131 set local-preference 10
3132 set community additive no-export
3133 route-map rm-blackhole permit 20
3135 ! Set local-pref as requested
3136 route-map rm-prefmod permit 10
3137 match community cm-prefmod-100
3138 set local-preference 100
3139 route-map rm-prefmod permit 20
3140 match community cm-prefmod-200
3141 set local-preference 200
3142 route-map rm-prefmod permit 30
3143 match community cm-prefmod-300
3144 set local-preference 300
3145 route-map rm-prefmod permit 40
3146 match community cm-prefmod-400
3147 set local-preference 400
3148 route-map rm-prefmod permit 50
3150 ! Community actions to take on receipt of route.
3151 route-map rm-community-in permit 10
3152 description check for blackholing, no point continuing if it matches.
3153 match community cm-blackhole
3155 route-map rm-community-in permit 20
3156 match community cm-set-no-export
3159 route-map rm-community-in permit 30
3160 match community cme-prefmod-range
3162 route-map rm-community-in permit 40
3164 ! #####################################################################
3165 ! Community actions to take when advertising a route.
3166 ! These are filtering route-maps,
3168 ! Deny customer routes to upstream with cust-only set.
3169 route-map rm-community-filt-to-upstream deny 10
3170 match community cm-learnt-cust
3171 match community cm-cust-only
3172 route-map rm-community-filt-to-upstream permit 20
3174 ! Deny customer routes to other customers with upstream-only set.
3175 route-map rm-community-filt-to-cust deny 10
3176 match community cm-learnt-cust
3177 match community cm-upstream-only
3178 route-map rm-community-filt-to-cust permit 20
3180 ! ###################################################################
3181 ! The top-level route-maps applied to sessions. Further entries could
3182 ! be added obviously..
3185 route-map rm-cust-in permit 10
3186 call rm-community-in
3188 route-map rm-cust-in permit 20
3189 set community additive 64512:3100
3190 route-map rm-cust-in permit 30
3192 route-map rm-cust-out permit 10
3193 call rm-community-filt-to-cust
3195 route-map rm-cust-out permit 20
3197 ! Upstream transit ASes
3198 route-map rm-upstream-out permit 10
3199 description filter customer prefixes which are marked cust-only
3200 call rm-community-filt-to-upstream
3202 route-map rm-upstream-out permit 20
3203 description only customer routes are provided to upstreams/peers
3204 match community cm-learnt-cust
3207 ! outbound policy is same as for upstream
3208 route-map rm-peer-out permit 10
3209 call rm-upstream-out
3211 route-map rm-peer-in permit 10
3212 set community additive 64512:3200
3215 Example of how to set up a 6-Bone connection.
3219 ! bgpd configuration
3220 ! ==================
3222 ! MP-BGP configuration
3225 bgp router-id 10.0.0.1
3226 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 remote-as `as-number`
3229 network 3ffe:506::/32
3230 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 activate
3231 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 route-map set-nexthop out
3232 neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 remote-as `as-number`
3233 neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 route-map set-nexthop out
3236 ipv6 access-list all permit any
3238 ! Set output nexthop address.
3240 route-map set-nexthop permit 10
3241 match ipv6 address all
3242 set ipv6 nexthop global 3ffe:1cfa:0:2:2c0:4fff:fe68:a225
3243 set ipv6 nexthop local fe80::2c0:4fff:fe68:a225
3249 .. include:: routeserver.rst
3251 .. include:: rpki.rst
3253 .. include:: wecmp_linkbw.rst
3255 .. include:: flowspec.rst
3257 .. [#med-transitivity-rant] For some set of objects to have an order, there *must* be some binary ordering relation that is defined for *every* combination of those objects, and that relation *must* be transitive. I.e.:, if the relation operator is <, and if a < b and b < c then that relation must carry over and it *must* be that a < c for the objects to have an order. The ordering relation may allow for equality, i.e. a < b and b < a may both be true and imply that a and b are equal in the order and not distinguished by it, in which case the set has a partial order. Otherwise, if there is an order, all the objects have a distinct place in the order and the set has a total order)
3258 .. [bgp-route-osci-cond] McPherson, D. and Gill, V. and Walton, D., "Border Gateway Protocol (BGP) Persistent Route Oscillation Condition", IETF RFC3345
3259 .. [stable-flexible-ibgp] Flavel, A. and M. Roughan, "Stable and flexible iBGP", ACM SIGCOMM 2009
3260 .. [ibgp-correctness] Griffin, T. and G. Wilfong, "On the correctness of IBGP configuration", ACM SIGCOMM 2002