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 .. _bgp-basic-concepts:
43 .. _bgp-autonomous-systems:
50 An AS is a connected group of one or more IP prefixes run by one or more
51 network operators which has a SINGLE and CLEARLY DEFINED routing policy.
53 Each AS has an identifying number associated with it called an :abbr:`ASN
54 (Autonomous System Number)`. This is a two octet value ranging in value from 1
55 to 65535. The AS numbers 64512 through 65535 are defined as private AS numbers.
56 Private AS numbers must not be advertised on the global Internet.
58 The :abbr:`ASN (Autonomous System Number)` is one of the essential elements of
59 BGP. BGP is a distance vector routing protocol, and the AS-Path framework
60 provides distance vector metric and loop detection to BGP.
62 .. seealso:: :rfc:`1930`
64 .. _bgp-address-families:
69 Multiprotocol extensions enable BGP to carry routing information for multiple
70 network layer protocols. BGP supports an Address Family Identifier (AFI) for
71 IPv4 and IPv6. Support is also provided for multiple sets of per-AFI
72 information via the BGP Subsequent Address Family Identifier (SAFI). FRR
73 supports SAFIs for unicast information, labeled information (:rfc:`3107` and
74 :rfc:`8277`), and Layer 3 VPN information (:rfc:`4364` and :rfc:`4659`).
76 .. _bgp-route-selection:
81 The route selection process used by FRR's BGP implementation uses the following
82 decision criterion, starting at the top of the list and going towards the
83 bottom until one of the factors can be used.
87 Prefer higher local weight routes to lower routes.
89 2. **Local preference check**
91 Prefer higher local preference routes to lower.
93 3. **Local route check**
95 Prefer local routes (statics, aggregates, redistributed) to received routes.
97 4. **AS path length check**
99 Prefer shortest hop-count AS_PATHs.
103 Prefer the lowest origin type route. That is, prefer IGP origin routes to
104 EGP, to Incomplete routes.
108 Where routes with a MED were received from the same AS, prefer the route
109 with the lowest MED. :ref:`bgp-med`.
111 7. **External check**
113 Prefer the route received from an external, eBGP peer over routes received
114 from other types of peers.
116 8. **IGP cost check**
118 Prefer the route with the lower IGP cost.
120 9. **Multi-path check**
122 If multi-pathing is enabled, then check whether the routes not yet
123 distinguished in preference may be considered equal. If
124 :clicmd:`bgp bestpath as-path multipath-relax` is set, all such routes are
125 considered equal, otherwise routes received via iBGP with identical AS_PATHs
126 or routes received from eBGP neighbours in the same AS are considered equal.
128 10. **Already-selected external check**
130 Where both routes were received from eBGP peers, then prefer the route
131 which is already selected. Note that this check is not applied if
132 :clicmd:`bgp bestpath compare-routerid` is configured. This check can
133 prevent some cases of oscillation.
135 11. **Router-ID check**
137 Prefer the route with the lowest `router-ID`. If the route has an
138 `ORIGINATOR_ID` attribute, through iBGP reflection, then that router ID is
139 used, otherwise the `router-ID` of the peer the route was received from is
142 12. **Cluster-List length check**
144 The route with the shortest cluster-list length is used. The cluster-list
145 reflects the iBGP reflection path the route has taken.
149 Prefer the route received from the peer with the higher transport layer
150 address, as a last-resort tie-breaker.
152 .. _bgp-capability-negotiation:
154 Capability Negotiation
155 ----------------------
157 When adding IPv6 routing information exchange feature to BGP. There were some
158 proposals. :abbr:`IETF (Internet Engineering Task Force)`
159 :abbr:`IDR (Inter Domain Routing)` adopted a proposal called Multiprotocol
160 Extension for BGP. The specification is described in :rfc:`2283`. The protocol
161 does not define new protocols. It defines new attributes to existing BGP. When
162 it is used exchanging IPv6 routing information it is called BGP-4+. When it is
163 used for exchanging multicast routing information it is called MBGP.
165 *bgpd* supports Multiprotocol Extension for BGP. So if a remote peer supports
166 the protocol, *bgpd* can exchange IPv6 and/or multicast routing information.
168 Traditional BGP did not have the feature to detect a remote peer's
169 capabilities, e.g. whether it can handle prefix types other than IPv4 unicast
170 routes. This was a big problem using Multiprotocol Extension for BGP in an
171 operational network. :rfc:`2842` adopted a feature called Capability
172 Negotiation. *bgpd* use this Capability Negotiation to detect the remote peer's
173 capabilities. If a peer is only configured as an IPv4 unicast neighbor, *bgpd*
174 does not send these Capability Negotiation packets (at least not unless other
175 optional BGP features require capability negotiation).
177 By default, FRR will bring up peering with minimal common capability for the
178 both sides. For example, if the local router has unicast and multicast
179 capabilities and the remote router only has unicast capability the local router
180 will establish the connection with unicast only capability. When there are no
181 common capabilities, FRR sends Unsupported Capability error and then resets the
184 .. _bgp-router-configuration:
186 BGP Router Configuration
187 ========================
192 First of all you must configure BGP router with the :clicmd:`router bgp ASN`
193 command. The AS number is an identifier for the autonomous system. The BGP
194 protocol uses the AS number for detecting whether the BGP connection is
195 internal or external.
197 .. index:: router bgp ASN
198 .. clicmd:: router bgp ASN
200 Enable a BGP protocol process with the specified ASN. After
201 this statement you can input any `BGP Commands`.
203 .. index:: no router bgp ASN
204 .. clicmd:: no router bgp ASN
206 Destroy a BGP protocol process with the specified ASN.
208 .. index:: bgp router-id A.B.C.D
209 .. clicmd:: bgp router-id A.B.C.D
211 This command specifies the router-ID. If *bgpd* connects to *zebra* it gets
212 interface and address information. In that case default router ID value is
213 selected as the largest IP Address of the interfaces. When `router zebra` is
214 not enabled *bgpd* can't get interface information so `router-id` is set to
215 0.0.0.0. So please set router-id by hand.
218 .. _bgp-multiple-autonomous-systems:
220 Multiple Autonomous Systems
221 ---------------------------
223 FRR's BGP implementation is capable of running multiple autonomous systems at
224 once. Each configured AS corresponds to a :ref:`zebra-vrf`. In the past, to get
225 the same functionality the network administrator had to run a new *bgpd*
226 process; using VRFs allows multiple autonomous systems to be handled in a
229 When using multiple autonomous systems, all router config blocks after the
230 first one must specify a VRF to be the target of BGP's route selection. This
231 VRF must be unique within respect to all other VRFs being used for the same
232 purpose, i.e. two different autonomous systems cannot use the same VRF.
233 However, the same AS can be used with different VRFs.
237 The separated nature of VRFs makes it possible to peer a single *bgpd*
238 process to itself, on one machine. Note that this can be done fully within
239 BGP without a corresponding VRF in the kernel or Zebra, which enables some
240 practical use cases such as :ref:`route reflectors <bgp-route-reflector>`
243 Configuration of additional autonomous systems, or of a router that targets a
244 specific VRF, is accomplished with the following command:
246 .. index:: router bgp ASN vrf VRFNAME
247 .. clicmd:: router bgp ASN vrf VRFNAME
249 ``VRFNAME`` is matched against VRFs configured in the kernel. When ``vrf
250 VRFNAME`` is not specified, the BGP protocol process belongs to the default
253 An example configuration with multiple autonomous systems might look like this:
258 neighbor 10.0.0.1 remote-as 20
259 neighbor 10.0.0.2 remote-as 30
261 router bgp 2 vrf blue
262 neighbor 10.0.0.3 remote-as 40
263 neighbor 10.0.0.4 remote-as 50
266 neighbor 10.0.0.5 remote-as 60
267 neighbor 10.0.0.6 remote-as 70
270 In the past this feature done differently and the following commands were
271 required to enable the functionality. They are now deprecated.
274 This command is deprecated and may be safely removed from the config.
276 .. index:: bgp multiple-instance
277 .. clicmd:: bgp multiple-instance
279 Enable BGP multiple instance feature. Because this is now the default
280 configuration this command will not be displayed in the running
284 This command is deprecated and may be safely removed from the config.
286 .. index:: no bgp multiple-instance
287 .. clicmd:: no bgp multiple-instance
289 In previous versions of FRR, this command disabled the BGP multiple instance
290 feature. This functionality is automatically turned on when BGP multiple
291 instances or views exist so this command no longer does anything.
293 .. seealso:: :ref:`bgp-vrf-route-leaking`
294 .. seealso:: :ref:`zebra-vrf`
302 In addition to supporting multiple autonomous systems, FRR's BGP implementation
303 also supports *views*.
305 BGP views are almost the same as normal BGP processes, except that routes
306 selected by BGP are not installed into the kernel routing table. Each BGP view
307 provides an independent set of routing information which is only distributed
308 via BGP. Multiple views can be supported, and BGP view information is always
309 independent from other routing protocols and Zebra/kernel routes. BGP views use
310 the core instance (i.e., default VRF) for communication with peers.
312 .. index:: router bgp AS-NUMBER view NAME
313 .. clicmd:: router bgp AS-NUMBER view NAME
315 Make a new BGP view. You can use an arbitrary word for the ``NAME``. Routes
316 selected by the view are not installed into the kernel routing table.
318 With this command, you can setup Route Server like below.
324 neighbor 10.0.0.1 remote-as 2
325 neighbor 10.0.0.2 remote-as 3
328 neighbor 10.0.0.3 remote-as 4
329 neighbor 10.0.0.4 remote-as 5
331 .. index:: show [ip] bgp view NAME
332 .. clicmd:: show [ip] bgp view NAME
334 Display the routing table of BGP view ``NAME``.
340 .. index:: bgp bestpath as-path confed
341 .. clicmd:: bgp bestpath as-path confed
343 This command specifies that the length of confederation path sets and
344 sequences should should be taken into account during the BGP best path
347 .. index:: bgp bestpath as-path multipath-relax
348 .. clicmd:: bgp bestpath as-path multipath-relax
350 This command specifies that BGP decision process should consider paths
351 of equal AS_PATH length candidates for multipath computation. Without
352 the knob, the entire AS_PATH must match for multipath computation.
354 .. clicmd:: bgp bestpath compare-routerid
356 Ensure that when comparing routes where both are equal on most metrics,
357 including local-pref, AS_PATH length, IGP cost, MED, that the tie is broken
360 If this option is enabled, then the already-selected check, where
361 already selected eBGP routes are preferred, is skipped.
363 If a route has an `ORIGINATOR_ID` attribute because it has been reflected,
364 that `ORIGINATOR_ID` will be used. Otherwise, the router-ID of the peer the
365 route was received from will be used.
367 The advantage of this is that the route-selection (at this point) will be
368 more deterministic. The disadvantage is that a few or even one lowest-ID
369 router may attract all traffic to otherwise-equal paths because of this
370 check. It may increase the possibility of MED or IGP oscillation, unless
371 other measures were taken to avoid these. The exact behaviour will be
372 sensitive to the iBGP and reflection topology.
376 Administrative Distance Metrics
377 -------------------------------
379 .. index:: distance bgp (1-255) (1-255) (1-255)
380 .. clicmd:: distance bgp (1-255) (1-255) (1-255)
382 This command change distance value of BGP. The arguments are the distance
383 values for for external routes, internal routes and local routes
386 .. index:: distance (1-255) A.B.C.D/M
387 .. clicmd:: distance (1-255) A.B.C.D/M
389 .. index:: distance (1-255) A.B.C.D/M WORD
390 .. clicmd:: distance (1-255) A.B.C.D/M WORD
392 Sets the administrative distance for a particular route.
394 .. _bgp-route-flap-dampening:
399 .. clicmd:: bgp dampening (1-45) (1-20000) (1-20000) (1-255)
401 This command enables BGP route-flap dampening and specifies dampening parameters.
404 Half-life time for the penalty
407 Value to start reusing a route
410 Value to start suppressing a route
413 Maximum duration to suppress a stable route
415 The route-flap damping algorithm is compatible with :rfc:`2439`. The use of
416 this command is not recommended nowadays.
419 https://www.ripe.net/publications/docs/ripe-378
423 Multi-Exit Discriminator
424 ------------------------
426 The BGP :abbr:`MED (Multi-Exit Discriminator)` attribute has properties which
427 can cause subtle convergence problems in BGP. These properties and problems
428 have proven to be hard to understand, at least historically, and may still not
429 be widely understood. The following attempts to collect together and present
430 what is known about MED, to help operators and FRR users in designing and
431 configuring their networks.
433 The BGP :abbr:`MED` attribute is intended to allow one AS to indicate its
434 preferences for its ingress points to another AS. The MED attribute will not be
435 propagated on to another AS by the receiving AS - it is 'non-transitive' in the
438 E.g., if AS X and AS Y have 2 different BGP peering points, then AS X might set
439 a MED of 100 on routes advertised at one and a MED of 200 at the other. When AS
440 Y selects between otherwise equal routes to or via AS X, AS Y should prefer to
441 take the path via the lower MED peering of 100 with AS X. Setting the MED
442 allows an AS to influence the routing taken to it within another, neighbouring
445 In this use of MED it is not really meaningful to compare the MED value on
446 routes where the next AS on the paths differs. E.g., if AS Y also had a route
447 for some destination via AS Z in addition to the routes from AS X, and AS Z had
448 also set a MED, it wouldn't make sense for AS Y to compare AS Z's MED values to
449 those of AS X. The MED values have been set by different administrators, with
450 different frames of reference.
452 The default behaviour of BGP therefore is to not compare MED values across
453 routes received from different neighbouring ASes. In FRR this is done by
454 comparing the neighbouring, left-most AS in the received AS_PATHs of the routes
455 and only comparing MED if those are the same.
457 Unfortunately, this behaviour of MED, of sometimes being compared across routes
458 and sometimes not, depending on the properties of those other routes, means MED
459 can cause the order of preference over all the routes to be undefined. That is,
460 given routes A, B, and C, if A is preferred to B, and B is preferred to C, then
461 a well-defined order should mean the preference is transitive (in the sense of
462 orders [#med-transitivity-rant]_) and that A would be preferred to C.
464 However, when MED is involved this need not be the case. With MED it is
465 possible that C is actually preferred over A. So A is preferred to B, B is
466 preferred to C, but C is preferred to A. This can be true even where BGP
467 defines a deterministic 'most preferred' route out of the full set of A,B,C.
468 With MED, for any given set of routes there may be a deterministically
469 preferred route, but there need not be any way to arrange them into any order
470 of preference. With unmodified MED, the order of preference of routes literally
473 That MED can induce non-transitive preferences over routes can cause issues.
474 Firstly, it may be perceived to cause routing table churn locally at speakers;
475 secondly, and more seriously, it may cause routing instability in iBGP
476 topologies, where sets of speakers continually oscillate between different
479 The first issue arises from how speakers often implement routing decisions.
480 Though BGP defines a selection process that will deterministically select the
481 same route as best at any given speaker, even with MED, that process requires
482 evaluating all routes together. For performance and ease of implementation
483 reasons, many implementations evaluate route preferences in a pair-wise fashion
484 instead. Given there is no well-defined order when MED is involved, the best
485 route that will be chosen becomes subject to implementation details, such as
486 the order the routes are stored in. That may be (locally) non-deterministic,
487 e.g.: it may be the order the routes were received in.
489 This indeterminism may be considered undesirable, though it need not cause
490 problems. It may mean additional routing churn is perceived, as sometimes more
491 updates may be produced than at other times in reaction to some event .
493 This first issue can be fixed with a more deterministic route selection that
494 ensures routes are ordered by the neighbouring AS during selection.
495 :clicmd:`bgp deterministic-med`. This may reduce the number of updates as routes
496 are received, and may in some cases reduce routing churn. Though, it could
497 equally deterministically produce the largest possible set of updates in
498 response to the most common sequence of received updates.
500 A deterministic order of evaluation tends to imply an additional overhead of
501 sorting over any set of n routes to a destination. The implementation of
502 deterministic MED in FRR scales significantly worse than most sorting
503 algorithms at present, with the number of paths to a given destination. That
504 number is often low enough to not cause any issues, but where there are many
505 paths, the deterministic comparison may quickly become increasingly expensive
508 Deterministic local evaluation can *not* fix the second, more major, issue of
509 MED however. Which is that the non-transitive preference of routes MED can
510 cause may lead to routing instability or oscillation across multiple speakers
511 in iBGP topologies. This can occur with full-mesh iBGP, but is particularly
512 problematic in non-full-mesh iBGP topologies that further reduce the routing
513 information known to each speaker. This has primarily been documented with iBGP
514 :ref:`route-reflection <bgp-route-reflector>` topologies. However, any
515 route-hiding technologies potentially could also exacerbate oscillation with MED.
517 This second issue occurs where speakers each have only a subset of routes, and
518 there are cycles in the preferences between different combinations of routes -
519 as the undefined order of preference of MED allows - and the routes are
520 distributed in a way that causes the BGP speakers to 'chase' those cycles. This
521 can occur even if all speakers use a deterministic order of evaluation in route
524 E.g., speaker 4 in AS A might receive a route from speaker 2 in AS X, and from
525 speaker 3 in AS Y; while speaker 5 in AS A might receive that route from
526 speaker 1 in AS Y. AS Y might set a MED of 200 at speaker 1, and 100 at speaker
527 3. I.e, using ASN:ID:MED to label the speakers:
533 X:2------|--A:4-------A:5--|-Y:1:200
539 Assuming all other metrics are equal (AS_PATH, ORIGIN, 0 IGP costs), then based
540 on the RFC4271 decision process speaker 4 will choose X:2 over Y:3:100, based
541 on the lower ID of 2. Speaker 4 advertises X:2 to speaker 5. Speaker 5 will
542 continue to prefer Y:1:200 based on the ID, and advertise this to speaker 4.
543 Speaker 4 will now have the full set of routes, and the Y:1:200 it receives
544 from 5 will beat X:2, but when speaker 4 compares Y:1:200 to Y:3:100 the MED
545 check now becomes active as the ASes match, and now Y:3:100 is preferred.
546 Speaker 4 therefore now advertises Y:3:100 to 5, which will also agrees that
547 Y:3:100 is preferred to Y:1:200, and so withdraws the latter route from 4.
548 Speaker 4 now has only X:2 and Y:3:100, and X:2 beats Y:3:100, and so speaker 4
549 implicitly updates its route to speaker 5 to X:2. Speaker 5 sees that Y:1:200
550 beats X:2 based on the ID, and advertises Y:1:200 to speaker 4, and the cycle
553 The root cause is the lack of a clear order of preference caused by how MED
554 sometimes is and sometimes is not compared, leading to this cycle in the
555 preferences between the routes:
560 /---> X:2 ---beats---> Y:3:100 --\\
563 \\---beats--- Y:1:200 <---beats---/
567 This particular type of oscillation in full-mesh iBGP topologies can be
568 avoided by speakers preferring already selected, external routes rather than
569 choosing to update to new a route based on a post-MED metric (e.g. router-ID),
570 at the cost of a non-deterministic selection process. FRR implements this, as
571 do many other implementations, so long as it is not overridden by setting
572 :clicmd:`bgp bestpath compare-routerid`, and see also
573 :ref:`bgp-route-selection`.
575 However, more complex and insidious cycles of oscillation are possible with
576 iBGP route-reflection, which are not so easily avoided. These have been
577 documented in various places. See, e.g.:
579 - [bgp-route-osci-cond]_
580 - [stable-flexible-ibgp]_
581 - [ibgp-correctness]_
583 for concrete examples and further references.
585 There is as of this writing *no* known way to use MED for its original purpose;
586 *and* reduce routing information in iBGP topologies; *and* be sure to avoid the
587 instability problems of MED due the non-transitive routing preferences it can
588 induce; in general on arbitrary networks.
590 There may be iBGP topology specific ways to reduce the instability risks, even
591 while using MED, e.g.: by constraining the reflection topology and by tuning
592 IGP costs between route-reflector clusters, see :rfc:`3345` for details. In the
593 near future, the Add-Path extension to BGP may also solve MED oscillation while
594 still allowing MED to be used as intended, by distributing "best-paths per
595 neighbour AS". This would be at the cost of distributing at least as many
596 routes to all speakers as a full-mesh iBGP would, if not more, while also
597 imposing similar CPU overheads as the "Deterministic MED" feature at each
600 More generally, the instability problems that MED can introduce on more
601 complex, non-full-mesh, iBGP topologies may be avoided either by:
603 - Setting :clicmd:`bgp always-compare-med`, however this allows MED to be compared
604 across values set by different neighbour ASes, which may not produce
605 coherent desirable results, of itself.
606 - Effectively ignoring MED by setting MED to the same value (e.g.: 0) using
607 :clicmd:`set metric METRIC` on all received routes, in combination with
608 setting :clicmd:`bgp always-compare-med` on all speakers. This is the simplest
609 and most performant way to avoid MED oscillation issues, where an AS is happy
610 not to allow neighbours to inject this problematic metric.
612 As MED is evaluated after the AS_PATH length check, another possible use for
613 MED is for intra-AS steering of routes with equal AS_PATH length, as an
614 extension of the last case above. As MED is evaluated before IGP metric, this
615 can allow cold-potato routing to be implemented to send traffic to preferred
616 hand-offs with neighbours, rather than the closest hand-off according to the
619 Note that even if action is taken to address the MED non-transitivity issues,
620 other oscillations may still be possible. E.g., on IGP cost if iBGP and IGP
621 topologies are at cross-purposes with each other - see the Flavel and Roughan
622 paper above for an example. Hence the guideline that the iBGP topology should
623 follow the IGP topology.
625 .. index:: bgp deterministic-med
626 .. clicmd:: bgp deterministic-med
628 Carry out route-selection in way that produces deterministic answers
629 locally, even in the face of MED and the lack of a well-defined order of
630 preference it can induce on routes. Without this option the preferred route
631 with MED may be determined largely by the order that routes were received
634 Setting this option will have a performance cost that may be noticeable when
635 there are many routes for each destination. Currently in FRR it is
636 implemented in a way that scales poorly as the number of routes per
637 destination increases.
639 The default is that this option is not set.
641 Note that there are other sources of indeterminism in the route selection
642 process, specifically, the preference for older and already selected routes
643 from eBGP peers, :ref:`bgp-route-selection`.
645 .. index:: bgp always-compare-med
646 .. clicmd:: bgp always-compare-med
648 Always compare the MED on routes, even when they were received from
649 different neighbouring ASes. Setting this option makes the order of
650 preference of routes more defined, and should eliminate MED induced
653 If using this option, it may also be desirable to use
654 :clicmd:`set metric METRIC` to set MED to 0 on routes received from external
657 This option can be used, together with :clicmd:`set metric METRIC` to use
658 MED as an intra-AS metric to steer equal-length AS_PATH routes to, e.g.,
666 .. index:: network A.B.C.D/M
667 .. clicmd:: network A.B.C.D/M
669 This command adds the announcement network.
674 address-family ipv4 unicast
678 This configuration example says that network 10.0.0.0/8 will be
679 announced to all neighbors. Some vendors' routers don't advertise
680 routes if they aren't present in their IGP routing tables; `bgpd`
681 doesn't care about IGP routes when announcing its routes.
683 .. index:: no network A.B.C.D/M
684 .. clicmd:: no network A.B.C.D/M
686 .. _bgp-route-aggregation:
691 .. index:: aggregate-address A.B.C.D/M
692 .. clicmd:: aggregate-address A.B.C.D/M
694 This command specifies an aggregate address.
696 .. index:: aggregate-address A.B.C.D/M as-set
697 .. clicmd:: aggregate-address A.B.C.D/M as-set
699 This command specifies an aggregate address. Resulting routes include
702 .. index:: aggregate-address A.B.C.D/M summary-only
703 .. clicmd:: aggregate-address A.B.C.D/M summary-only
705 This command specifies an aggregate address. Aggregated routes will
708 .. index:: no aggregate-address A.B.C.D/M
709 .. clicmd:: no aggregate-address A.B.C.D/M
711 .. _bgp-redistribute-to-bgp:
716 .. index:: redistribute kernel
717 .. clicmd:: redistribute kernel
719 Redistribute kernel route to BGP process.
721 .. index:: redistribute static
722 .. clicmd:: redistribute static
724 Redistribute static route to BGP process.
726 .. index:: redistribute connected
727 .. clicmd:: redistribute connected
729 Redistribute connected route to BGP process.
731 .. index:: redistribute rip
732 .. clicmd:: redistribute rip
734 Redistribute RIP route to BGP process.
736 .. index:: redistribute ospf
737 .. clicmd:: redistribute ospf
739 Redistribute OSPF route to BGP process.
741 .. index:: redistribute vpn
742 .. clicmd:: redistribute vpn
744 Redistribute VNC routes to BGP process.
746 .. index:: update-delay MAX-DELAY
747 .. clicmd:: update-delay MAX-DELAY
749 .. index:: update-delay MAX-DELAY ESTABLISH-WAIT
750 .. clicmd:: update-delay MAX-DELAY ESTABLISH-WAIT
752 This feature is used to enable read-only mode on BGP process restart or when
753 BGP process is cleared using 'clear ip bgp \*'. When applicable, read-only
754 mode would begin as soon as the first peer reaches Established status and a
755 timer for max-delay seconds is started.
757 During this mode BGP doesn't run any best-path or generate any updates to its
758 peers. This mode continues until:
760 1. All the configured peers, except the shutdown peers, have sent explicit EOR
761 (End-Of-RIB) or an implicit-EOR. The first keep-alive after BGP has reached
762 Established is considered an implicit-EOR.
763 If the establish-wait optional value is given, then BGP will wait for
764 peers to reach established from the beginning of the update-delay till the
765 establish-wait period is over, i.e. the minimum set of established peers for
766 which EOR is expected would be peers established during the establish-wait
767 window, not necessarily all the configured neighbors.
768 2. max-delay period is over.
770 On hitting any of the above two conditions, BGP resumes the decision process
771 and generates updates to its peers.
773 Default max-delay is 0, i.e. the feature is off by default.
775 .. index:: table-map ROUTE-MAP-NAME
776 .. clicmd:: table-map ROUTE-MAP-NAME
778 This feature is used to apply a route-map on route updates from BGP to
779 Zebra. All the applicable match operations are allowed, such as match on
780 prefix, next-hop, communities, etc. Set operations for this attach-point are
781 limited to metric and next-hop only. Any operation of this feature does not
782 affect BGPs internal RIB.
784 Supported for ipv4 and ipv6 address families. It works on multi-paths as
785 well, however, metric setting is based on the best-path only.
792 .. _bgp-defining-peers:
797 .. index:: neighbor PEER remote-as ASN
798 .. clicmd:: neighbor PEER remote-as ASN
800 Creates a new neighbor whose remote-as is ASN. PEER can be an IPv4 address
801 or an IPv6 address or an interface to use for the connection.
806 neighbor 10.0.0.1 remote-as 2
808 In this case my router, in AS-1, is trying to peer with AS-2 at 10.0.0.1.
810 This command must be the first command used when configuring a neighbor. If
811 the remote-as is not specified, *bgpd* will complain like this: ::
813 can't find neighbor 10.0.0.1
815 .. index:: neighbor PEER remote-as internal
816 .. clicmd:: neighbor PEER remote-as internal
818 Create a peer as you would when you specify an ASN, except that if the
819 peers ASN is different than mine as specified under the :clicmd:`router bgp ASN`
820 command the connection will be denied.
822 .. index:: neighbor PEER remote-as external
823 .. clicmd:: neighbor PEER remote-as external
825 Create a peer as you would when you specify an ASN, except that if the
826 peers ASN is the same as mine as specified under the :clicmd:`router bgp ASN`
827 command the connection will be denied.
829 .. index:: [no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group PGNAME
830 .. clicmd:: [no] bgp listen range <A.B.C.D/M|X:X::X:X/M> peer-group PGNAME
832 Accept connections from any peers in the specified prefix. Configuration
833 from the specified peer-group is used to configure these peers.
837 When using BGP listen ranges, if the associated peer group has TCP MD5
838 authentication configured, your kernel must support this on prefixes. On
839 Linux, this support was added in kernel version 4.14. If your kernel does
840 not support this feature you will get a warning in the log file, and the
841 listen range will only accept connections from peers without MD5 configured.
843 Additionally, we have observed that when using this option at scale (several
844 hundred peers) the kernel may hit its option memory limit. In this situation
845 you will see error messages like:
847 ``bgpd: sockopt_tcp_signature: setsockopt(23): Cannot allocate memory``
849 In this case you need to increase the value of the sysctl
850 ``net.core.optmem_max`` to allow the kernel to allocate the necessary option
853 .. _bgp-configuring-peers:
858 .. index:: [no] neighbor PEER shutdown
859 .. clicmd:: [no] neighbor PEER shutdown
861 Shutdown the peer. We can delete the neighbor's configuration by
862 ``no neighbor PEER remote-as ASN`` but all configuration of the neighbor
863 will be deleted. When you want to preserve the configuration, but want to
864 drop the BGP peer, use this syntax.
866 .. index:: [no] neighbor PEER disable-connected-check
867 .. clicmd:: [no] neighbor PEER disable-connected-check
869 Allow peerings between directly connected eBGP peers using loopback
872 .. index:: [no] neighbor PEER ebgp-multihop
873 .. clicmd:: [no] neighbor PEER ebgp-multihop
875 .. index:: [no] neighbor PEER description ...
876 .. clicmd:: [no] neighbor PEER description ...
878 Set description of the peer.
880 .. index:: [no] neighbor PEER version VERSION
881 .. clicmd:: [no] neighbor PEER version VERSION
883 Set up the neighbor's BGP version. `version` can be `4`, `4+` or `4-`. BGP
884 version `4` is the default value used for BGP peering. BGP version `4+`
885 means that the neighbor supports Multiprotocol Extensions for BGP-4. BGP
886 version `4-` is similar but the neighbor speaks the old Internet-Draft
887 revision 00's Multiprotocol Extensions for BGP-4. Some routing software is
888 still using this version.
890 .. index:: [no] neighbor PEER interface IFNAME
891 .. clicmd:: [no] neighbor PEER interface IFNAME
893 When you connect to a BGP peer over an IPv6 link-local address, you have to
894 specify the IFNAME of the interface used for the connection. To specify
895 IPv4 session addresses, see the ``neighbor PEER update-source`` command
898 This command is deprecated and may be removed in a future release. Its use
901 .. index:: [no] neighbor PEER next-hop-self [all]
902 .. clicmd:: [no] neighbor PEER next-hop-self [all]
904 This command specifies an announced route's nexthop as being equivalent to
905 the address of the bgp router if it is learned via eBGP. If the optional
906 keyword `all` is specified the modification is done also for routes learned
909 .. index:: [no] neighbor PEER update-source <IFNAME|ADDRESS>
910 .. clicmd:: [no] neighbor PEER update-source <IFNAME|ADDRESS>
912 Specify the IPv4 source address to use for the :abbr:`BGP` session to this
913 neighbour, may be specified as either an IPv4 address directly or as an
914 interface name (in which case the *zebra* daemon MUST be running in order
915 for *bgpd* to be able to retrieve interface state).
920 neighbor foo update-source 192.168.0.1
921 neighbor bar update-source lo0
924 .. index:: [no] neighbor PEER default-originate
925 .. clicmd:: [no] neighbor PEER default-originate
927 *bgpd*'s default is to not announce the default route (0.0.0.0/0) even if it
928 is in routing table. When you want to announce default routes to the peer,
931 .. index:: neighbor PEER port PORT
932 .. clicmd:: neighbor PEER port PORT
934 .. index:: neighbor PEER send-community
935 .. clicmd:: neighbor PEER send-community
937 .. index:: [no] neighbor PEER weight WEIGHT
938 .. clicmd:: [no] neighbor PEER weight WEIGHT
940 This command specifies a default `weight` value for the neighbor's routes.
942 .. index:: [no] neighbor PEER maximum-prefix NUMBER
943 .. clicmd:: [no] neighbor PEER maximum-prefix NUMBER
945 Sets a maximum number of prefixes we can receive from a given peer. If this
946 number is exceeded, the BGP session will be destroyed.
948 In practice, it is generally preferable to use a prefix-list to limit what
949 prefixes are received from the peer instead of using this knob. Tearing down
950 the BGP session when a limit is exceeded is far more destructive than merely
951 rejecting undesired prefixes. The prefix-list method is also much more
952 granular and offers much smarter matching criterion than number of received
953 prefixes, making it more suited to implementing policy.
955 .. index:: [no] neighbor PEER local-as AS-NUMBER [no-prepend] [replace-as]
956 .. clicmd:: [no] neighbor PEER local-as AS-NUMBER [no-prepend] [replace-as]
958 Specify an alternate AS for this BGP process when interacting with the
959 specified peer. With no modifiers, the specified local-as is prepended to
960 the received AS_PATH when receiving routing updates from the peer, and
961 prepended to the outgoing AS_PATH (after the process local AS) when
962 transmitting local routes to the peer.
964 If the no-prepend attribute is specified, then the supplied local-as is not
965 prepended to the received AS_PATH.
967 If the replace-as attribute is specified, then only the supplied local-as is
968 prepended to the AS_PATH when transmitting local-route updates to this peer.
970 Note that replace-as can only be specified if no-prepend is.
972 This command is only allowed for eBGP peers.
974 .. index:: [no] neighbor PEER ttl-security hops NUMBER
975 .. clicmd:: [no] neighbor PEER ttl-security hops NUMBER
977 This command enforces Generalized TTL Security Mechanism (GTSM), as
978 specified in RFC 5082. With this command, only neighbors that are the
979 specified number of hops away will be allowed to become neighbors. This
980 command is mutually exclusive with *ebgp-multihop*.
982 .. index:: [no] neighbor PEER capability extended-nexthop
983 .. clicmd:: [no] neighbor PEER capability extended-nexthop
985 Allow bgp to negotiate the extended-nexthop capability with it's peer.
986 If you are peering over a v6 LL address then this capability is turned
987 on automatically. If you are peering over a v6 Global Address then
988 turning on this command will allow BGP to install v4 routes with
989 v6 nexthops if you do not have v4 configured on interfaces.
991 .. index:: [no] bgp fast-external-failover
992 .. clicmd:: [no] bgp fast-external-failover
994 This command causes bgp to not take down ebgp peers immediately
995 when a link flaps. `bgp fast-external-failover` is the default
996 and will not be displayed as part of a `show run`. The no form
997 of the command turns off this ability.
999 .. index:: [no] bgp default ipv4-unicast
1000 .. clicmd:: [no] bgp default ipv4-unicast
1002 This command allows the user to specify that v4 peering is turned
1003 on by default or not. This command defaults to on and is not displayed.
1004 The `no bgp default ipv4-unicast` form of the command is displayed.
1006 .. _bgp-peer-filtering:
1011 .. index:: neighbor PEER distribute-list NAME [in|out]
1012 .. clicmd:: neighbor PEER distribute-list NAME [in|out]
1014 This command specifies a distribute-list for the peer. `direct` is
1017 .. index:: neighbor PEER prefix-list NAME [in|out]
1018 .. clicmd:: neighbor PEER prefix-list NAME [in|out]
1020 .. index:: neighbor PEER filter-list NAME [in|out]
1021 .. clicmd:: neighbor PEER filter-list NAME [in|out]
1023 .. index:: neighbor PEER route-map NAME [in|out]
1024 .. clicmd:: neighbor PEER route-map NAME [in|out]
1026 Apply a route-map on the neighbor. `direct` must be `in` or `out`.
1028 .. index:: bgp route-reflector allow-outbound-policy
1029 .. clicmd:: bgp route-reflector allow-outbound-policy
1031 By default, attribute modification via route-map policy out is not reflected
1032 on reflected routes. This option allows the modifications to be reflected as
1033 well. Once enabled, it affects all reflected routes.
1040 Peer groups are used to help improve scaling by generating the same
1041 update information to all members of a peer group. Note that this means
1042 that the routes generated by a member of a peer group will be sent back
1043 to that originating peer with the originator identifier attribute set to
1044 indicated the originating peer. All peers not associated with a
1045 specific peer group are treated as belonging to a default peer group,
1046 and will share updates.
1048 .. index:: neighbor WORD peer-group
1049 .. clicmd:: neighbor WORD peer-group
1051 This command defines a new peer group.
1053 .. index:: neighbor PEER peer-group PGNAME
1054 .. clicmd:: neighbor PEER peer-group PGNAME
1056 This command bind specific peer to peer group WORD.
1058 .. index:: neighbor PEER solo
1059 .. clicmd:: neighbor PEER solo
1061 This command is used to indicate that routes advertised by the peer
1062 should not be reflected back to the peer. This command only is only
1063 meaningful when there is a single peer defined in the peer-group.
1065 Capability Negotiation
1066 ^^^^^^^^^^^^^^^^^^^^^^
1068 .. index:: neighbor PEER strict-capability-match
1069 .. clicmd:: neighbor PEER strict-capability-match
1071 .. index:: no neighbor PEER strict-capability-match
1072 .. clicmd:: no neighbor PEER strict-capability-match
1074 Strictly compares remote capabilities and local capabilities. If
1075 capabilities are different, send Unsupported Capability error then reset
1078 You may want to disable sending Capability Negotiation OPEN message optional
1079 parameter to the peer when remote peer does not implement Capability
1080 Negotiation. Please use *dont-capability-negotiate* command to disable the
1083 .. index:: neighbor PEER dont-capability-negotiate
1084 .. clicmd:: neighbor PEER dont-capability-negotiate
1086 .. index:: no neighbor PEER dont-capability-negotiate
1087 .. clicmd:: no neighbor PEER dont-capability-negotiate
1089 Suppress sending Capability Negotiation as OPEN message optional parameter
1090 to the peer. This command only affects the peer is configured other than
1091 IPv4 unicast configuration.
1093 When remote peer does not have capability negotiation feature, remote peer
1094 will not send any capabilities at all. In that case, bgp configures the peer
1095 with configured capabilities.
1097 You may prefer locally configured capabilities more than the negotiated
1098 capabilities even though remote peer sends capabilities. If the peer is
1099 configured by *override-capability*, *bgpd* ignores received capabilities
1100 then override negotiated capabilities with configured values.
1102 .. index:: neighbor PEER override-capability
1103 .. clicmd:: neighbor PEER override-capability
1105 .. index:: no neighbor PEER override-capability
1106 .. clicmd:: no neighbor PEER override-capability
1108 Override the result of Capability Negotiation with local configuration.
1109 Ignore remote peer's capability value.
1111 .. _bgp-as-path-access-lists:
1113 AS Path Access Lists
1114 --------------------
1116 AS path access list is user defined AS path.
1118 .. index:: ip as-path access-list WORD permit|deny LINE
1119 .. clicmd:: ip as-path access-list WORD permit|deny LINE
1121 This command defines a new AS path access list.
1123 .. index:: no ip as-path access-list WORD
1124 .. clicmd:: no ip as-path access-list WORD
1126 .. index:: no ip as-path access-list WORD permit|deny LINE
1127 .. clicmd:: no ip as-path access-list WORD permit|deny LINE
1129 .. _bgp-using-as-path-in-route-map:
1131 Using AS Path in Route Map
1132 --------------------------
1134 .. index:: match as-path WORD
1135 .. clicmd:: match as-path WORD
1138 .. index:: set as-path prepend AS-PATH
1139 .. clicmd:: set as-path prepend AS-PATH
1141 Prepend the given string of AS numbers to the AS_PATH.
1143 .. index:: set as-path prepend last-as NUM
1144 .. clicmd:: set as-path prepend last-as NUM
1146 Prepend the existing last AS number (the leftmost ASN) to the AS_PATH.
1148 .. _bgp-communities-attribute:
1150 Communities Attribute
1151 ---------------------
1153 The BGP communities attribute is widely used for implementing policy routing.
1154 Network operators can manipulate BGP communities attribute based on their
1155 network policy. BGP communities attribute is defined in :rfc:`1997` and
1156 :rfc:`1998`. It is an optional transitive attribute, therefore local policy can
1157 travel through different autonomous system.
1159 The communities attribute is a set of communities values. Each community value
1160 is 4 octet long. The following format is used to define the community value.
1163 This format represents 4 octet communities value. ``AS`` is high order 2
1164 octet in digit format. ``VAL`` is low order 2 octet in digit format. This
1165 format is useful to define AS oriented policy value. For example,
1166 ``7675:80`` can be used when AS 7675 wants to pass local policy value 80 to
1170 ``internet`` represents well-known communities value 0.
1172 ``graceful-shutdown``
1173 ``graceful-shutdown`` represents well-known communities value
1174 ``GRACEFUL_SHUTDOWN`` ``0xFFFF0000`` ``65535:0``. :rfc:`8326` implements
1175 the purpose Graceful BGP Session Shutdown to reduce the amount of
1176 lost traffic when taking BGP sessions down for maintenance. The use
1177 of the community needs to be supported from your peers side to
1178 actually have any effect.
1181 ``accept-own`` represents well-known communities value ``ACCEPT_OWN``
1182 ``0xFFFF0001`` ``65535:1``. :rfc:`7611` implements a way to signal
1183 to a router to accept routes with a local nexthop address. This
1184 can be the case when doing policing and having traffic having a
1185 nexthop located in another VRF but still local interface to the
1186 router. It is recommended to read the RFC for full details.
1188 ``route-filter-translated-v4``
1189 ``route-filter-translated-v4`` represents well-known communities value
1190 ``ROUTE_FILTER_TRANSLATED_v4`` ``0xFFFF0002`` ``65535:2``.
1193 ``route-filter-v4`` represents well-known communities value
1194 ``ROUTE_FILTER_v4`` ``0xFFFF0003`` ``65535:3``.
1196 ``route-filter-translated-v6``
1197 ``route-filter-translated-v6`` represents well-known communities value
1198 ``ROUTE_FILTER_TRANSLATED_v6`` ``0xFFFF0004`` ``65535:4``.
1201 ``route-filter-v6`` represents well-known communities value
1202 ``ROUTE_FILTER_v6`` ``0xFFFF0005`` ``65535:5``.
1205 ``llgr-stale`` represents well-known communities value ``LLGR_STALE``
1206 ``0xFFFF0006`` ``65535:6``.
1207 Assigned and intended only for use with routers supporting the
1208 Long-lived Graceful Restart Capability as described in
1209 [Draft-IETF-uttaro-idr-bgp-persistence]_.
1210 Routers receiving routes with this community may (depending on
1211 implementation) choose allow to reject or modify routes on the
1212 presence or absence of this community.
1215 ``no-llgr`` represents well-known communities value ``NO_LLGR``
1216 ``0xFFFF0007`` ``65535:7``.
1217 Assigned and intended only for use with routers supporting the
1218 Long-lived Graceful Restart Capability as described in
1219 [Draft-IETF-uttaro-idr-bgp-persistence]_.
1220 Routers receiving routes with this community may (depending on
1221 implementation) choose allow to reject or modify routes on the
1222 presence or absence of this community.
1224 ``accept-own-nexthop``
1225 ``accept-own-nexthop`` represents well-known communities value
1226 ``accept-own-nexthop`` ``0xFFFF0008`` ``65535:8``.
1227 [Draft-IETF-agrewal-idr-accept-own-nexthop]_ describes
1228 how to tag and label VPN routes to be able to send traffic between VRFs
1229 via an internal layer 2 domain on the same PE device. Refer to
1230 [Draft-IETF-agrewal-idr-accept-own-nexthop]_ for full details.
1233 ``blackhole`` represents well-known communities value ``BLACKHOLE``
1234 ``0xFFFF029A`` ``65535:666``. :rfc:`7999` documents sending prefixes to
1235 EBGP peers and upstream for the purpose of blackholing traffic.
1236 Prefixes tagged with the this community should normally not be
1237 re-advertised from neighbors of the originating network. It is
1238 recommended upon receiving prefixes tagged with this community to
1239 add ``NO_EXPORT`` and ``NO_ADVERTISE``.
1242 ``no-export`` represents well-known communities value ``NO_EXPORT``
1243 ``0xFFFFFF01``. All routes carry this value must not be advertised to
1244 outside a BGP confederation boundary. If neighboring BGP peer is part of BGP
1245 confederation, the peer is considered as inside a BGP confederation
1246 boundary, so the route will be announced to the peer.
1249 ``no-advertise`` represents well-known communities value ``NO_ADVERTISE``
1250 ``0xFFFFFF02``. All routes carry this value must not be advertise to other
1254 ``local-AS`` represents well-known communities value ``NO_EXPORT_SUBCONFED``
1255 ``0xFFFFFF03``. All routes carry this value must not be advertised to
1256 external BGP peers. Even if the neighboring router is part of confederation,
1257 it is considered as external BGP peer, so the route will not be announced to
1261 ``no-peer`` represents well-known communities value ``NOPEER``
1262 ``0xFFFFFF04`` ``65535:65284``. :rfc:`3765` is used to communicate to
1263 another network how the originating network want the prefix propagated.
1265 When the communities attribute is received duplicate community values in the
1266 attribute are ignored and value is sorted in numerical order.
1268 .. [Draft-IETF-uttaro-idr-bgp-persistence] <https://tools.ietf.org/id/draft-uttaro-idr-bgp-persistence-04.txt>
1269 .. [Draft-IETF-agrewal-idr-accept-own-nexthop] <https://tools.ietf.org/id/draft-agrewal-idr-accept-own-nexthop-00.txt>
1271 .. _bgp-community-lists:
1275 Community lists are user defined lists of community attribute values. These
1276 lists can be used for matching or manipulating the communities attribute in
1279 There are two types of community list:
1282 This type accepts an explicit value for the attribute.
1285 This type accepts a regular expression. Because the regex must be
1286 interpreted on each use expanded community lists are slower than standard
1289 .. index:: ip community-list standard NAME permit|deny COMMUNITY
1290 .. clicmd:: ip community-list standard NAME permit|deny COMMUNITY
1292 This command defines a new standard community list. ``COMMUNITY`` is
1293 communities value. The ``COMMUNITY`` is compiled into community structure.
1294 We can define multiple community list under same name. In that case match
1295 will happen user defined order. Once the community list matches to
1296 communities attribute in BGP updates it return permit or deny by the
1297 community list definition. When there is no matched entry, deny will be
1298 returned. When ``COMMUNITY`` is empty it matches to any routes.
1300 .. index:: ip community-list expanded NAME permit|deny COMMUNITY
1301 .. clicmd:: ip community-list expanded NAME permit|deny COMMUNITY
1303 This command defines a new expanded community list. ``COMMUNITY`` is a
1304 string expression of communities attribute. ``COMMUNITY`` can be a regular
1305 expression (:ref:`bgp-regular-expressions`) to match the communities
1306 attribute in BGP updates. The expanded community is only used to filter,
1310 It is recommended to use the more explicit versions of this command.
1312 .. index:: ip community-list NAME permit|deny COMMUNITY
1313 .. clicmd:: ip community-list NAME permit|deny COMMUNITY
1315 When the community list type is not specified, the community list type is
1316 automatically detected. If ``COMMUNITY`` can be compiled into communities
1317 attribute, the community list is defined as a standard community list.
1318 Otherwise it is defined as an expanded community list. This feature is left
1319 for backward compatibility. Use of this feature is not recommended.
1322 .. index:: no ip community-list [standard|expanded] NAME
1323 .. clicmd:: no ip community-list [standard|expanded] NAME
1325 Deletes the community list specified by ``NAME``. All community lists share
1326 the same namespace, so it's not necessary to specify ``standard`` or
1327 ``expanded``; these modifiers are purely aesthetic.
1329 .. index:: show ip community-list [NAME]
1330 .. clicmd:: show ip community-list [NAME]
1332 Displays community list information. When ``NAME`` is specified the
1333 specified community list's information is shown.
1337 # show ip community-list
1338 Named Community standard list CLIST
1339 permit 7675:80 7675:100 no-export
1341 Named Community expanded list EXPAND
1344 # show ip community-list CLIST
1345 Named Community standard list CLIST
1346 permit 7675:80 7675:100 no-export
1350 .. _bgp-numbered-community-lists:
1352 Numbered Community Lists
1353 ^^^^^^^^^^^^^^^^^^^^^^^^
1355 When number is used for BGP community list name, the number has
1356 special meanings. Community list number in the range from 1 and 99 is
1357 standard community list. Community list number in the range from 100
1358 to 199 is expanded community list. These community lists are called
1359 as numbered community lists. On the other hand normal community lists
1360 is called as named community lists.
1362 .. index:: ip community-list (1-99) permit|deny COMMUNITY
1363 .. clicmd:: ip community-list (1-99) permit|deny COMMUNITY
1365 This command defines a new community list. The argument to (1-99) defines
1366 the list identifier.
1368 .. index:: ip community-list (100-199) permit|deny COMMUNITY
1369 .. clicmd:: ip community-list (100-199) permit|deny COMMUNITY
1371 This command defines a new expanded community list. The argument to
1372 (100-199) defines the list identifier.
1374 .. _bgp-using-communities-in-route-map:
1376 Using Communities in Route Maps
1377 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1379 In :ref:`route-map` we can match on or set the BGP communities attribute. Using
1380 this feature network operator can implement their network policy based on BGP
1381 communities attribute.
1383 The ollowing commands can be used in route maps:
1385 .. index:: match community WORD exact-match [exact-match]
1386 .. clicmd:: match community WORD exact-match [exact-match]
1388 This command perform match to BGP updates using community list WORD. When
1389 the one of BGP communities value match to the one of communities value in
1390 community list, it is match. When `exact-match` keyword is specified, match
1391 happen only when BGP updates have completely same communities value
1392 specified in the community list.
1394 .. index:: set community <none|COMMUNITY> additive
1395 .. clicmd:: set community <none|COMMUNITY> additive
1397 This command sets the community value in BGP updates. If the attribute is
1398 already configured, the newly provided value replaces the old one unless the
1399 ``additive`` keyword is specified, in which case the new value is appended
1400 to the existing value.
1402 If ``none`` is specified as the community value, the communities attribute
1405 It is not possible to set an expanded community list.
1407 .. index:: set comm-list WORD delete
1408 .. clicmd:: set comm-list WORD delete
1410 This command remove communities value from BGP communities attribute. The
1411 ``word`` is community list name. When BGP route's communities value matches
1412 to the community list ``word``, the communities value is removed. When all
1413 of communities value is removed eventually, the BGP update's communities
1414 attribute is completely removed.
1416 .. _bgp-communities-example:
1418 Example Configuration
1419 ^^^^^^^^^^^^^^^^^^^^^
1421 The following configuration is exemplary of the most typical usage of BGP
1422 communities attribute. In the example, AS 7675 provides an upstream Internet
1423 connection to AS 100. When the following configuration exists in AS 7675, the
1424 network operator of AS 100 can set local preference in AS 7675 network by
1425 setting BGP communities attribute to the updates.
1430 neighbor 192.168.0.1 remote-as 100
1431 address-family ipv4 unicast
1432 neighbor 192.168.0.1 route-map RMAP in
1435 ip community-list 70 permit 7675:70
1436 ip community-list 70 deny
1437 ip community-list 80 permit 7675:80
1438 ip community-list 80 deny
1439 ip community-list 90 permit 7675:90
1440 ip community-list 90 deny
1442 route-map RMAP permit 10
1444 set local-preference 70
1446 route-map RMAP permit 20
1448 set local-preference 80
1450 route-map RMAP permit 30
1452 set local-preference 90
1455 The following configuration announces ``10.0.0.0/8`` from AS 100 to AS 7675.
1456 The route has communities value ``7675:80`` so when above configuration exists
1457 in AS 7675, the announced routes' local preference value will be set to 80.
1463 neighbor 192.168.0.2 remote-as 7675
1464 address-family ipv4 unicast
1465 neighbor 192.168.0.2 route-map RMAP out
1468 ip prefix-list PLIST permit 10.0.0.0/8
1470 route-map RMAP permit 10
1471 match ip address prefix-list PLIST
1472 set community 7675:80
1475 The following configuration is an example of BGP route filtering using
1476 communities attribute. This configuration only permit BGP routes which has BGP
1477 communities value ``0:80`` or ``0:90``. The network operator can set special
1478 internal communities value at BGP border router, then limit the BGP route
1479 announcements into the internal network.
1484 neighbor 192.168.0.1 remote-as 100
1485 address-family ipv4 unicast
1486 neighbor 192.168.0.1 route-map RMAP in
1489 ip community-list 1 permit 0:80 0:90
1491 route-map RMAP permit in
1495 The following example filters BGP routes which have a community value of
1496 ``1:1``. When there is no match community-list returns ``deny``. To avoid
1497 filtering all routes, a ``permit`` line is set at the end of the
1503 neighbor 192.168.0.1 remote-as 100
1504 address-family ipv4 unicast
1505 neighbor 192.168.0.1 route-map RMAP in
1508 ip community-list standard FILTER deny 1:1
1509 ip community-list standard FILTER permit
1511 route-map RMAP permit 10
1512 match community FILTER
1515 The communities value keyword ``internet`` has special meanings in standard
1516 community lists. In the below example ``internet`` matches all BGP routes even
1517 if the route does not have communities attribute at all. So community list
1518 ``INTERNET`` is the same as ``FILTER`` in the previous example.
1522 ip community-list standard INTERNET deny 1:1
1523 ip community-list standard INTERNET permit internet
1526 The following configuration is an example of communities value deletion. With
1527 this configuration the community values ``100:1`` and ``100:2`` are removed
1528 from BGP updates. For communities value deletion, only ``permit``
1529 community-list is used. ``deny`` community-list is ignored.
1534 neighbor 192.168.0.1 remote-as 100
1535 address-family ipv4 unicast
1536 neighbor 192.168.0.1 route-map RMAP in
1539 ip community-list standard DEL permit 100:1 100:2
1541 route-map RMAP permit 10
1542 set comm-list DEL delete
1545 .. _bgp-extended-communities-attribute:
1547 Extended Communities Attribute
1548 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1550 BGP extended communities attribute is introduced with MPLS VPN/BGP technology.
1551 MPLS VPN/BGP expands capability of network infrastructure to provide VPN
1552 functionality. At the same time it requires a new framework for policy routing.
1553 With BGP Extended Communities Attribute we can use Route Target or Site of
1554 Origin for implementing network policy for MPLS VPN/BGP.
1556 BGP Extended Communities Attribute is similar to BGP Communities Attribute. It
1557 is an optional transitive attribute. BGP Extended Communities Attribute can
1558 carry multiple Extended Community value. Each Extended Community value is
1561 BGP Extended Communities Attribute provides an extended range compared with BGP
1562 Communities Attribute. Adding to that there is a type field in each value to
1563 provides community space structure.
1565 There are two format to define Extended Community value. One is AS based format
1566 the other is IP address based format.
1569 This is a format to define AS based Extended Community value. ``AS`` part
1570 is 2 octets Global Administrator subfield in Extended Community value.
1571 ``VAL`` part is 4 octets Local Administrator subfield. ``7675:100``
1572 represents AS 7675 policy value 100.
1575 This is a format to define IP address based Extended Community value.
1576 ``IP-Address`` part is 4 octets Global Administrator subfield. ``VAL`` part
1577 is 2 octets Local Administrator subfield.
1579 .. _bgp-extended-community-lists:
1581 Extended Community Lists
1582 ^^^^^^^^^^^^^^^^^^^^^^^^
1584 .. index:: ip extcommunity-list standard NAME permit|deny EXTCOMMUNITY
1585 .. clicmd:: ip extcommunity-list standard NAME permit|deny EXTCOMMUNITY
1587 This command defines a new standard extcommunity-list. `extcommunity` is
1588 extended communities value. The `extcommunity` is compiled into extended
1589 community structure. We can define multiple extcommunity-list under same
1590 name. In that case match will happen user defined order. Once the
1591 extcommunity-list matches to extended communities attribute in BGP updates
1592 it return permit or deny based upon the extcommunity-list definition. When
1593 there is no matched entry, deny will be returned. When `extcommunity` is
1594 empty it matches to any routes.
1596 .. index:: ip extcommunity-list expanded NAME permit|deny LINE
1597 .. clicmd:: ip extcommunity-list expanded NAME permit|deny LINE
1599 This command defines a new expanded extcommunity-list. `line` is a string
1600 expression of extended communities attribute. `line` can be a regular
1601 expression (:ref:`bgp-regular-expressions`) to match an extended communities
1602 attribute in BGP updates.
1604 .. index:: no ip extcommunity-list NAME
1605 .. clicmd:: no ip extcommunity-list NAME
1607 .. index:: no ip extcommunity-list standard NAME
1608 .. clicmd:: no ip extcommunity-list standard NAME
1610 .. index:: no ip extcommunity-list expanded NAME
1611 .. clicmd:: no ip extcommunity-list expanded NAME
1613 These commands delete extended community lists specified by `name`. All of
1614 extended community lists shares a single name space. So extended community
1615 lists can be removed simply specifying the name.
1617 .. index:: show ip extcommunity-list
1618 .. clicmd:: show ip extcommunity-list
1620 .. index:: show ip extcommunity-list NAME
1621 .. clicmd:: show ip extcommunity-list NAME
1623 This command displays current extcommunity-list information. When `name` is
1624 specified the community list's information is shown.::
1626 # show ip extcommunity-list
1629 .. _bgp-extended-communities-in-route-map:
1631 BGP Extended Communities in Route Map
1632 """""""""""""""""""""""""""""""""""""
1634 .. index:: match extcommunity WORD
1635 .. clicmd:: match extcommunity WORD
1637 .. index:: set extcommunity rt EXTCOMMUNITY
1638 .. clicmd:: set extcommunity rt EXTCOMMUNITY
1640 This command set Route Target value.
1642 .. index:: set extcommunity soo EXTCOMMUNITY
1643 .. clicmd:: set extcommunity soo EXTCOMMUNITY
1645 This command set Site of Origin value.
1648 Note that the extended expanded community is only used for `match` rule, not for
1651 .. _bgp-large-communities-attribute:
1653 Large Communities Attribute
1654 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
1656 The BGP Large Communities attribute was introduced in Feb 2017 with
1659 The BGP Large Communities Attribute is similar to the BGP Communities Attribute
1660 except that it has 3 components instead of two and each of which are 4 octets
1661 in length. Large Communities bring additional functionality and convenience
1662 over traditional communities, specifically the fact that the ``GLOBAL`` part
1663 below is now 4 octets wide allowing seamless use in networks using 4-byte ASNs.
1665 ``GLOBAL:LOCAL1:LOCAL2``
1666 This is the format to define Large Community values. Referencing :rfc:`8195`
1667 the values are commonly referred to as follows:
1669 - The ``GLOBAL`` part is a 4 octet Global Administrator field, commonly used
1670 as the operators AS number.
1671 - The ``LOCAL1`` part is a 4 octet Local Data Part 1 subfield referred to as
1673 - The ``LOCAL2`` part is a 4 octet Local Data Part 2 field and referred to
1674 as the parameter subfield.
1676 As an example, ``65551:1:10`` represents AS 65551 function 1 and parameter
1677 10. The referenced RFC above gives some guidelines on recommended usage.
1679 .. _bgp-large-community-lists:
1681 Large Community Lists
1682 """""""""""""""""""""
1684 Two types of large community lists are supported, namely `standard` and
1687 .. index:: ip large-community-list standard NAME permit|deny LARGE-COMMUNITY
1688 .. clicmd:: ip large-community-list standard NAME permit|deny LARGE-COMMUNITY
1690 This command defines a new standard large-community-list. `large-community`
1691 is the Large Community value. We can add multiple large communities under
1692 same name. In that case the match will happen in the user defined order.
1693 Once the large-community-list matches the Large Communities attribute in BGP
1694 updates it will return permit or deny based upon the large-community-list
1695 definition. When there is no matched entry, a deny will be returned. When
1696 `large-community` is empty it matches any routes.
1698 .. index:: ip large-community-list expanded NAME permit|deny LINE
1699 .. clicmd:: ip large-community-list expanded NAME permit|deny LINE
1701 This command defines a new expanded large-community-list. Where `line` is a
1702 string matching expression, it will be compared to the entire Large
1703 Communities attribute as a string, with each large-community in order from
1704 lowest to highest. `line` can also be a regular expression which matches
1705 this Large Community attribute.
1707 .. index:: no ip large-community-list NAME
1708 .. clicmd:: no ip large-community-list NAME
1710 .. index:: no ip large-community-list standard NAME
1711 .. clicmd:: no ip large-community-list standard NAME
1713 .. index:: no ip large-community-list expanded NAME
1714 .. clicmd:: no ip large-community-list expanded NAME
1716 These commands delete Large Community lists specified by `name`. All Large
1717 Community lists share a single namespace. This means Large Community lists
1718 can be removed by simply specifying the name.
1720 .. index:: show ip large-community-list
1721 .. clicmd:: show ip large-community-list
1723 .. index:: show ip large-community-list NAME
1724 .. clicmd:: show ip large-community-list NAME
1726 This command display current large-community-list information. When
1727 `name` is specified the community list information is shown.
1729 .. index:: show ip bgp large-community-info
1730 .. clicmd:: show ip bgp large-community-info
1732 This command displays the current large communities in use.
1734 .. _bgp-large-communities-in-route-map:
1736 Large Communities in Route Map
1737 """"""""""""""""""""""""""""""
1739 .. index:: match large-community LINE
1740 .. clicmd:: match large-community LINE
1742 Where `line` can be a simple string to match, or a regular expression. It
1743 is very important to note that this match occurs on the entire
1744 large-community string as a whole, where each large-community is ordered
1745 from lowest to highest.
1747 .. index:: set large-community LARGE-COMMUNITY
1748 .. clicmd:: set large-community LARGE-COMMUNITY
1750 .. index:: set large-community LARGE-COMMUNITY LARGE-COMMUNITY
1751 .. clicmd:: set large-community LARGE-COMMUNITY LARGE-COMMUNITY
1753 .. index:: set large-community LARGE-COMMUNITY additive
1754 .. clicmd:: set large-community LARGE-COMMUNITY additive
1756 These commands are used for setting large-community values. The first
1757 command will overwrite any large-communities currently present.
1758 The second specifies two large-communities, which overwrites the current
1759 large-community list. The third will add a large-community value without
1760 overwriting other values. Multiple large-community values can be specified.
1762 Note that the large expanded community is only used for `match` rule, not for
1770 *bgpd* supports :abbr:`L3VPN (Layer 3 Virtual Private Networks)` :abbr:`VRFs
1771 (Virtual Routing and Forwarding)` for IPv4 :rfc:`4364` and IPv6 :rfc:`4659`.
1772 L3VPN routes, and their associated VRF MPLS labels, can be distributed to VPN
1773 SAFI neighbors in the *default*, i.e., non VRF, BGP instance. VRF MPLS labels
1774 are reached using *core* MPLS labels which are distributed using LDP or BGP
1775 labeled unicast. *bgpd* also supports inter-VRF route leaking.
1778 .. _bgp-vrf-route-leaking:
1783 BGP routes may be leaked (i.e. copied) between a unicast VRF RIB and the VPN
1784 SAFI RIB of the default VRF for use in MPLS-based L3VPNs. Unicast routes may
1785 also be leaked between any VRFs (including the unicast RIB of the default BGP
1786 instanced). A shortcut syntax is also available for specifying leaking from one
1787 VRF to another VRF using the default instance's VPN RIB as the intemediary. A
1788 common application of the VRF-VRF feature is to connect a customer's private
1789 routing domain to a provider's VPN service. Leaking is configured from the
1790 point of view of an individual VRF: ``import`` refers to routes leaked from VPN
1791 to a unicast VRF, whereas ``export`` refers to routes leaked from a unicast VRF
1797 Routes exported from a unicast VRF to the VPN RIB must be augmented by two
1800 - an :abbr:`RD (Route Distinguisher)`
1801 - an :abbr:`RTLIST (Route-target List)`
1803 Configuration for these exported routes must, at a minimum, specify these two
1806 Routes imported from the VPN RIB to a unicast VRF are selected according to
1807 their RTLISTs. Routes whose RTLIST contains at least one route-target in
1808 common with the configured import RTLIST are leaked. Configuration for these
1809 imported routes must specify an RTLIST to be matched.
1811 The RD, which carries no semantic value, is intended to make the route unique
1812 in the VPN RIB among all routes of its prefix that originate from all the
1813 customers and sites that are attached to the provider's VPN service.
1814 Accordingly, each site of each customer is typically assigned an RD that is
1815 unique across the entire provider network.
1817 The RTLIST is a set of route-target extended community values whose purpose is
1818 to specify route-leaking policy. Typically, a customer is assigned a single
1819 route-target value for import and export to be used at all customer sites. This
1820 configuration specifies a simple topology wherein a customer has a single
1821 routing domain which is shared across all its sites. More complex routing
1822 topologies are possible through use of additional route-targets to augment the
1823 leaking of sets of routes in various ways.
1825 When using the shortcut syntax for vrf-to-vrf leaking, the RD and RT are
1828 General configuration
1829 ^^^^^^^^^^^^^^^^^^^^^
1831 Configuration of route leaking between a unicast VRF RIB and the VPN SAFI RIB
1832 of the default VRF is accomplished via commands in the context of a VRF
1835 .. index:: rd vpn export AS:NN|IP:nn
1836 .. clicmd:: rd vpn export AS:NN|IP:nn
1838 Specifies the route distinguisher to be added to a route exported from the
1839 current unicast VRF to VPN.
1841 .. index:: no rd vpn export [AS:NN|IP:nn]
1842 .. clicmd:: no rd vpn export [AS:NN|IP:nn]
1844 Deletes any previously-configured export route distinguisher.
1846 .. index:: rt vpn import|export|both RTLIST...
1847 .. clicmd:: rt vpn import|export|both RTLIST...
1849 Specifies the route-target list to be attached to a route (export) or the
1850 route-target list to match against (import) when exporting/importing between
1851 the current unicast VRF and VPN.
1853 The RTLIST is a space-separated list of route-targets, which are BGP
1854 extended community values as described in
1855 :ref:`bgp-extended-communities-attribute`.
1857 .. index:: no rt vpn import|export|both [RTLIST...]
1858 .. clicmd:: no rt vpn import|export|both [RTLIST...]
1860 Deletes any previously-configured import or export route-target list.
1862 .. index:: label vpn export (0..1048575)|auto
1863 .. clicmd:: label vpn export (0..1048575)|auto
1865 Specifies an optional MPLS label to be attached to a route exported from the
1866 current unicast VRF to VPN. If label is specified as ``auto``, the label
1867 value is automatically assigned from a pool maintained by the zebra
1868 daemon. If zebra is not running, automatic label assignment will not
1869 complete, which will block corresponding route export.
1871 .. index:: no label vpn export [(0..1048575)|auto]
1872 .. clicmd:: no label vpn export [(0..1048575)|auto]
1874 Deletes any previously-configured export label.
1876 .. index:: nexthop vpn export A.B.C.D|X:X::X:X
1877 .. clicmd:: nexthop vpn export A.B.C.D|X:X::X:X
1879 Specifies an optional nexthop value to be assigned to a route exported from
1880 the current unicast VRF to VPN. If left unspecified, the nexthop will be set
1881 to 0.0.0.0 or 0:0::0:0 (self).
1883 .. index:: no nexthop vpn export [A.B.C.D|X:X::X:X]
1884 .. clicmd:: no nexthop vpn export [A.B.C.D|X:X::X:X]
1886 Deletes any previously-configured export nexthop.
1888 .. index:: route-map vpn import|export MAP
1889 .. clicmd:: route-map vpn import|export MAP
1891 Specifies an optional route-map to be applied to routes imported or exported
1892 between the current unicast VRF and VPN.
1894 .. index:: no route-map vpn import|export [MAP]
1895 .. clicmd:: no route-map vpn import|export [MAP]
1897 Deletes any previously-configured import or export route-map.
1899 .. index:: import|export vpn
1900 .. clicmd:: import|export vpn
1902 Enables import or export of routes between the current unicast VRF and VPN.
1904 .. index:: no import|export vpn
1905 .. clicmd:: no import|export vpn
1907 Disables import or export of routes between the current unicast VRF and VPN.
1909 .. index:: import vrf VRFNAME
1910 .. clicmd:: import vrf VRFNAME
1912 Shortcut syntax for specifying automatic leaking from vrf VRFNAME to
1913 the current VRF using the VPN RIB as intermediary. The RD and RT
1914 are auto derived and should not be specified explicitly for either the
1915 source or destination VRF's.
1917 This shortcut syntax mode is not compatible with the explicit
1918 `import vpn` and `export vpn` statements for the two VRF's involved.
1919 The CLI will disallow attempts to configure incompatible leaking
1922 .. index:: no import vrf VRFNAME
1923 .. clicmd:: no import vrf VRFNAME
1925 Disables automatic leaking from vrf VRFNAME to the current VRF using
1926 the VPN RIB as intermediary.
1929 .. _bgp-cisco-compatibility:
1934 FRR has commands that change some configuration syntax and default behavior to
1935 behave more closely to Cisco conventions. These are deprecated and will be
1936 removed in a future version of FRR.
1939 Please transition to using the FRR specific syntax for your configuration.
1941 .. index:: bgp config-type cisco
1942 .. clicmd:: bgp config-type cisco
1944 Cisco compatible BGP configuration output.
1946 When this configuration line is specified:
1948 - ``no synchronization`` is displayed. This command does nothing and is for
1949 display purposes only.
1950 - ``no auto-summary`` is displayed.
1951 - The ``network`` and ``aggregate-address`` arguments are displayed as:
1957 FRR: network 10.0.0.0/8
1958 Cisco: network 10.0.0.0
1960 FRR: aggregate-address 192.168.0.0/24
1961 Cisco: aggregate-address 192.168.0.0 255.255.255.0
1963 Community attribute handling is also different. If no configuration is
1964 specified community attribute and extended community attribute are sent to
1965 the neighbor. If a user manually disables the feature, the community
1966 attribute is not sent to the neighbor. When ``bgp config-type cisco`` is
1967 specified, the community attribute is not sent to the neighbor by default.
1968 To send the community attribute user has to specify
1969 :clicmd:`neighbor A.B.C.D send-community` like so:
1975 neighbor 10.0.0.1 remote-as 1
1976 address-family ipv4 unicast
1977 no neighbor 10.0.0.1 send-community
1981 neighbor 10.0.0.1 remote-as 1
1982 address-family ipv4 unicast
1983 neighbor 10.0.0.1 send-community
1988 Please transition to using the FRR specific syntax for your configuration.
1990 .. index:: bgp config-type zebra
1991 .. clicmd:: bgp config-type zebra
1993 FRR style BGP configuration. This is the default.
2000 .. index:: show debug
2001 .. clicmd:: show debug
2003 Show all enabled debugs.
2005 .. index:: [no] debug bgp neighbor-events
2006 .. clicmd:: [no] debug bgp neighbor-events
2008 Enable or disable debugging for neighbor events. This provides general
2009 information on BGP events such as peer connection / disconnection, session
2010 establishment / teardown, and capability negotiation.
2012 .. index:: [no] debug bgp updates
2013 .. clicmd:: [no] debug bgp updates
2015 Enable or disable debugging for BGP updates. This provides information on
2016 BGP UPDATE messages transmitted and received between local and remote
2019 .. index:: [no] debug bgp keepalives
2020 .. clicmd:: [no] debug bgp keepalives
2022 Enable or disable debugging for BGP keepalives. This provides information on
2023 BGP KEEPALIVE messages transmitted and received between local and remote
2026 .. index:: [no] debug bgp bestpath <A.B.C.D/M|X:X::X:X/M>
2027 .. clicmd:: [no] debug bgp bestpath <A.B.C.D/M|X:X::X:X/M>
2029 Enable or disable debugging for bestpath selection on the specified prefix.
2031 .. index:: [no] debug bgp nht
2032 .. clicmd:: [no] debug bgp nht
2034 Enable or disable debugging of BGP nexthop tracking.
2036 .. index:: [no] debug bgp update-groups
2037 .. clicmd:: [no] debug bgp update-groups
2039 Enable or disable debugging of dynamic update groups. This provides general
2040 information on group creation, deletion, join and prune events.
2042 .. index:: [no] debug bgp zebra
2043 .. clicmd:: [no] debug bgp zebra
2045 Enable or disable debugging of communications between *bgpd* and *zebra*.
2047 Dumping Messages and Routing Tables
2048 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2050 .. index:: dump bgp all PATH [INTERVAL]
2051 .. clicmd:: dump bgp all PATH [INTERVAL]
2053 .. index:: dump bgp all-et PATH [INTERVAL]
2054 .. clicmd:: dump bgp all-et PATH [INTERVAL]
2056 .. index:: no dump bgp all [PATH] [INTERVAL]
2057 .. clicmd:: no dump bgp all [PATH] [INTERVAL]
2059 Dump all BGP packet and events to `path` file.
2060 If `interval` is set, a new file will be created for echo `interval` of
2061 seconds. The path `path` can be set with date and time formatting
2062 (strftime). The type ‘all-et’ enables support for Extended Timestamp Header
2063 (:ref:`packet-binary-dump-format`).
2065 .. index:: dump bgp updates PATH [INTERVAL]
2066 .. clicmd:: dump bgp updates PATH [INTERVAL]
2068 .. index:: dump bgp updates-et PATH [INTERVAL]
2069 .. clicmd:: dump bgp updates-et PATH [INTERVAL]
2071 .. index:: no dump bgp updates [PATH] [INTERVAL]
2072 .. clicmd:: no dump bgp updates [PATH] [INTERVAL]
2074 Dump only BGP updates messages to `path` file.
2075 If `interval` is set, a new file will be created for echo `interval` of
2076 seconds. The path `path` can be set with date and time formatting
2077 (strftime). The type ‘updates-et’ enables support for Extended Timestamp
2078 Header (:ref:`packet-binary-dump-format`).
2080 .. index:: dump bgp routes-mrt PATH
2081 .. clicmd:: dump bgp routes-mrt PATH
2083 .. index:: dump bgp routes-mrt PATH INTERVAL
2084 .. clicmd:: dump bgp routes-mrt PATH INTERVAL
2086 .. index:: no dump bgp route-mrt [PATH] [INTERVAL]
2087 .. clicmd:: no dump bgp route-mrt [PATH] [INTERVAL]
2089 Dump whole BGP routing table to `path`. This is heavy process. The path
2090 `path` can be set with date and time formatting (strftime). If `interval` is
2091 set, a new file will be created for echo `interval` of seconds.
2093 Note: the interval variable can also be set using hours and minutes: 04h20m00.
2096 .. _bgp-other-commands:
2101 .. index:: clear bgp ipv4|ipv6 \*
2102 .. clicmd:: clear bgp ipv4|ipv6 \*
2104 Clear all address family peers.
2106 .. index:: clear bgp ipv4|ipv6 PEER
2107 .. clicmd:: clear bgp ipv4|ipv6 PEER
2109 Clear peers which have addresses of X.X.X.X
2111 .. index:: clear bgp ipv4|ipv6 PEER soft in
2112 .. clicmd:: clear bgp ipv4|ipv6 PEER soft in
2114 Clear peer using soft reconfiguration.
2117 .. _bgp-displaying-bgp-information:
2119 Displaying BGP Information
2120 ==========================
2122 The following four commands display the IPv6 and IPv4 routing tables, depending
2123 on whether or not the ``ip`` keyword is used.
2124 Actually, :clicmd:`show ip bgp` command was used on older `Quagga` routing
2125 daemon project, while :clicmd:`show bgp` command is the new format. The choice
2126 has been done to keep old format with IPv4 routing table, while new format
2127 displays IPv6 routing table.
2129 .. index:: show ip bgp
2130 .. clicmd:: show ip bgp
2132 .. index:: show ip bgp A.B.C.D
2133 .. clicmd:: show ip bgp A.B.C.D
2136 .. clicmd:: show bgp
2138 .. index:: show bgp X:X::X:X
2139 .. clicmd:: show bgp X:X::X:X
2141 These commands display BGP routes. When no route is specified, the default
2142 is to display all BGP routes.
2146 BGP table version is 0, local router ID is 10.1.1.1
2147 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
2148 Origin codes: i - IGP, e - EGP, ? - incomplete
2150 Network Next Hop Metric LocPrf Weight Path
2151 \*> 1.1.1.1/32 0.0.0.0 0 32768 i
2153 Total number of prefixes 1
2155 Some other commands provide additional options for filtering the output.
2157 .. index:: show [ip] bgp regexp LINE
2158 .. clicmd:: show [ip] bgp regexp LINE
2160 This command displays BGP routes using AS path regular expression
2161 (:ref:`bgp-regular-expressions`).
2163 .. index:: show [ip] bgp summary
2164 .. clicmd:: show [ip] bgp summary
2166 Show a bgp peer summary for the specified address family.
2168 The old command structure :clicmd:`show ip bgp` may be removed in the future
2169 and should no longer be used. In order to reach the other BGP routing tables
2170 other than the IPv6 routing table given by :clicmd:`show bgp`, the new command
2171 structure is extended with :clicmd:`show bgp [afi] [safi]`.
2173 .. index:: show bgp [afi] [safi]
2174 .. clicmd:: show bgp [afi] [safi]
2176 .. index:: show bgp <ipv4|ipv6> <unicast|multicast|vpn|labeled-unicast>
2177 .. clicmd:: show bgp <ipv4|ipv6> <unicast|multicast|vpn|labeled-unicast>
2179 These commands display BGP routes for the specific routing table indicated by
2180 the selected afi and the selected safi. If no afi and no safi value is given,
2181 the command falls back to the default IPv6 routing table
2183 .. index:: show bgp [afi] [safi] summary
2184 .. clicmd:: show bgp [afi] [safi] summary
2186 Show a bgp peer summary for the specified address family, and subsequent
2189 .. index:: show bgp [afi] [safi] neighbor [PEER]
2190 .. clicmd:: show bgp [afi] [safi] neighbor [PEER]
2192 This command shows information on a specific BGP peer of the relevant
2193 afi and safi selected.
2195 .. index:: show bgp [afi] [safi] dampening dampened-paths
2196 .. clicmd:: show bgp [afi] [safi] dampening dampened-paths
2198 Display paths suppressed due to dampening of the selected afi and safi
2201 .. index:: show bgp [afi] [safi] dampening flap-statistics
2202 .. clicmd:: show bgp [afi] [safi] dampening flap-statistics
2204 Display flap statistics of routes of the selected afi and safi selected.
2206 .. _bgp-display-routes-by-community:
2208 Displaying Routes by Community Attribute
2209 ----------------------------------------
2211 The following commands allow displaying routes based on their community
2214 .. index:: show [ip] bgp <ipv4|ipv6> community
2215 .. clicmd:: show [ip] bgp <ipv4|ipv6> community
2217 .. index:: show [ip] bgp <ipv4|ipv6> community COMMUNITY
2218 .. clicmd:: show [ip] bgp <ipv4|ipv6> community COMMUNITY
2220 .. index:: show [ip] bgp <ipv4|ipv6> community COMMUNITY exact-match
2221 .. clicmd:: show [ip] bgp <ipv4|ipv6> community COMMUNITY exact-match
2223 These commands display BGP routes which have the community attribute.
2224 attribute. When ``COMMUNITY`` is specified, BGP routes that match that
2225 community are displayed. When `exact-match` is specified, it display only
2226 routes that have an exact match.
2228 .. index:: show [ip] bgp <ipv4|ipv6> community-list WORD
2229 .. clicmd:: show [ip] bgp <ipv4|ipv6> community-list WORD
2231 .. index:: show [ip] bgp <ipv4|ipv6> community-list WORD exact-match
2232 .. clicmd:: show [ip] bgp <ipv4|ipv6> community-list WORD exact-match
2234 These commands display BGP routes for the address family specified that
2235 match the specified community list. When `exact-match` is specified, it
2236 displays only routes that have an exact match.
2238 .. _bgp-display-routes-by-as-path:
2240 Displaying Routes by AS Path
2241 ----------------------------
2243 .. index:: show bgp ipv4|ipv6 regexp LINE
2244 .. clicmd:: show bgp ipv4|ipv6 regexp LINE
2246 This commands displays BGP routes that matches a regular
2247 expression `line` (:ref:`bgp-regular-expressions`).
2249 .. index:: show [ip] bgp ipv4 vpn
2250 .. clicmd:: show [ip] bgp ipv4 vpn
2252 .. index:: show [ip] bgp ipv6 vpn
2253 .. clicmd:: show [ip] bgp ipv6 vpn
2255 Print active IPV4 or IPV6 routes advertised via the VPN SAFI.
2257 .. index:: show bgp ipv4 vpn summary
2258 .. clicmd:: show bgp ipv4 vpn summary
2260 .. index:: show bgp ipv6 vpn summary
2261 .. clicmd:: show bgp ipv6 vpn summary
2263 Print a summary of neighbor connections for the specified AFI/SAFI combination.
2266 .. _bgp-route-reflector:
2271 BGP routers connected inside the same AS through BGP belong to an internal
2272 BGP session, or IBGP. In order to prevent routing table loops, IBGP does not
2273 advertise IBGP-learned routes to other routers in the same session. As such,
2274 IBGP requires a full mesh of all peers. For large networks, this quickly becomes
2275 unscalable. Introducing route reflectors removes the need for the full-mesh.
2277 When route reflectors are configured, these will reflect the routes announced
2278 by the peers configured as clients. A route reflector client is configured
2281 .. index:: neighbor PEER route-reflector-client
2282 .. clicmd:: neighbor PEER route-reflector-client
2284 .. index:: no neighbor PEER route-reflector-client
2285 .. clicmd:: no neighbor PEER route-reflector-client
2287 To avoid single points of failure, multiple route reflectors can be configured.
2289 A cluster is a collection of route reflectors and their clients, and is used
2290 by route reflectors to avoid looping.
2292 .. index:: bgp cluster-id A.B.C.D
2293 .. clicmd:: bgp cluster-id A.B.C.D
2300 You can set different routing policy for a peer. For example, you can set
2301 different filter for a peer.
2305 bgp multiple-instance
2308 neighbor 10.0.0.1 remote-as 2
2309 address-family ipv4 unicast
2310 neighbor 10.0.0.1 distribute-list 1 in
2314 neighbor 10.0.0.1 remote-as 2
2315 address-family ipv4 unicast
2316 neighbor 10.0.0.1 distribute-list 2 in
2319 This means BGP update from a peer 10.0.0.1 goes to both BGP view 1 and view 2.
2320 When the update is inserted into view 1, distribute-list 1 is applied. On the
2321 other hand, when the update is inserted into view 2, distribute-list 2 is
2325 .. _bgp-regular-expressions:
2327 BGP Regular Expressions
2328 =======================
2330 BGP regular expressions are based on :t:`POSIX 1003.2` regular expressions. The
2331 following description is just a quick subset of the POSIX regular expressions.
2335 Matches any single character.
2338 Matches 0 or more occurrences of pattern.
2341 Matches 1 or more occurrences of pattern.
2344 Match 0 or 1 occurrences of pattern.
2347 Matches the beginning of the line.
2350 Matches the end of the line.
2353 The ``_`` character has special meanings in BGP regular expressions. It
2354 matches to space and comma , and AS set delimiter ``{`` and ``}`` and AS
2355 confederation delimiter ``(`` and ``)``. And it also matches to the
2356 beginning of the line and the end of the line. So ``_`` can be used for AS
2357 value boundaries match. This character technically evaluates to
2361 .. _bgp-configuration-examples:
2363 Miscellaneous Configuration Examples
2364 ====================================
2366 Example of a session to an upstream, advertising only one prefix to it.
2371 bgp router-id 10.236.87.1
2372 neighbor upstream peer-group
2373 neighbor upstream remote-as 64515
2374 neighbor upstream capability dynamic
2375 neighbor 10.1.1.1 peer-group upstream
2376 neighbor 10.1.1.1 description ACME ISP
2378 address-family ipv4 unicast
2379 network 10.236.87.0/24
2380 neighbor upstream prefix-list pl-allowed-adv out
2383 ip prefix-list pl-allowed-adv seq 5 permit 82.195.133.0/25
2384 ip prefix-list pl-allowed-adv seq 10 deny any
2386 A more complex example including upstream, peer and customer sessions
2387 advertising global prefixes and NO_EXPORT prefixes and providing actions for
2388 customer routes based on community values. Extensive use is made of route-maps
2389 and the 'call' feature to support selective advertising of prefixes. This
2390 example is intended as guidance only, it has NOT been tested and almost
2391 certainly contains silly mistakes, if not serious flaws.
2396 bgp router-id 10.236.87.1
2397 neighbor upstream capability dynamic
2398 neighbor cust capability dynamic
2399 neighbor peer capability dynamic
2400 neighbor 10.1.1.1 remote-as 64515
2401 neighbor 10.1.1.1 peer-group upstream
2402 neighbor 10.2.1.1 remote-as 64516
2403 neighbor 10.2.1.1 peer-group upstream
2404 neighbor 10.3.1.1 remote-as 64517
2405 neighbor 10.3.1.1 peer-group cust-default
2406 neighbor 10.3.1.1 description customer1
2407 neighbor 10.4.1.1 remote-as 64518
2408 neighbor 10.4.1.1 peer-group cust
2409 neighbor 10.4.1.1 description customer2
2410 neighbor 10.5.1.1 remote-as 64519
2411 neighbor 10.5.1.1 peer-group peer
2412 neighbor 10.5.1.1 description peer AS 1
2413 neighbor 10.6.1.1 remote-as 64520
2414 neighbor 10.6.1.1 peer-group peer
2415 neighbor 10.6.1.1 description peer AS 2
2417 address-family ipv4 unicast
2418 network 10.123.456.0/24
2419 network 10.123.456.128/25 route-map rm-no-export
2420 neighbor upstream route-map rm-upstream-out out
2421 neighbor cust route-map rm-cust-in in
2422 neighbor cust route-map rm-cust-out out
2423 neighbor cust send-community both
2424 neighbor peer route-map rm-peer-in in
2425 neighbor peer route-map rm-peer-out out
2426 neighbor peer send-community both
2427 neighbor 10.3.1.1 prefix-list pl-cust1-network in
2428 neighbor 10.4.1.1 prefix-list pl-cust2-network in
2429 neighbor 10.5.1.1 prefix-list pl-peer1-network in
2430 neighbor 10.6.1.1 prefix-list pl-peer2-network in
2433 ip prefix-list pl-default permit 0.0.0.0/0
2435 ip prefix-list pl-upstream-peers permit 10.1.1.1/32
2436 ip prefix-list pl-upstream-peers permit 10.2.1.1/32
2438 ip prefix-list pl-cust1-network permit 10.3.1.0/24
2439 ip prefix-list pl-cust1-network permit 10.3.2.0/24
2441 ip prefix-list pl-cust2-network permit 10.4.1.0/24
2443 ip prefix-list pl-peer1-network permit 10.5.1.0/24
2444 ip prefix-list pl-peer1-network permit 10.5.2.0/24
2445 ip prefix-list pl-peer1-network permit 192.168.0.0/24
2447 ip prefix-list pl-peer2-network permit 10.6.1.0/24
2448 ip prefix-list pl-peer2-network permit 10.6.2.0/24
2449 ip prefix-list pl-peer2-network permit 192.168.1.0/24
2450 ip prefix-list pl-peer2-network permit 192.168.2.0/24
2451 ip prefix-list pl-peer2-network permit 172.16.1/24
2453 ip as-path access-list asp-own-as permit ^$
2454 ip as-path access-list asp-own-as permit _64512_
2456 ! #################################################################
2457 ! Match communities we provide actions for, on routes receives from
2458 ! customers. Communities values of <our-ASN>:X, with X, have actions:
2460 ! 100 - blackhole the prefix
2461 ! 200 - set no_export
2462 ! 300 - advertise only to other customers
2463 ! 400 - advertise only to upstreams
2464 ! 500 - set no_export when advertising to upstreams
2465 ! 2X00 - set local_preference to X00
2467 ! blackhole the prefix of the route
2468 ip community-list standard cm-blackhole permit 64512:100
2470 ! set no-export community before advertising
2471 ip community-list standard cm-set-no-export permit 64512:200
2473 ! advertise only to other customers
2474 ip community-list standard cm-cust-only permit 64512:300
2476 ! advertise only to upstreams
2477 ip community-list standard cm-upstream-only permit 64512:400
2479 ! advertise to upstreams with no-export
2480 ip community-list standard cm-upstream-noexport permit 64512:500
2482 ! set local-pref to least significant 3 digits of the community
2483 ip community-list standard cm-prefmod-100 permit 64512:2100
2484 ip community-list standard cm-prefmod-200 permit 64512:2200
2485 ip community-list standard cm-prefmod-300 permit 64512:2300
2486 ip community-list standard cm-prefmod-400 permit 64512:2400
2487 ip community-list expanded cme-prefmod-range permit 64512:2...
2489 ! Informational communities
2491 ! 3000 - learned from upstream
2492 ! 3100 - learned from customer
2493 ! 3200 - learned from peer
2495 ip community-list standard cm-learnt-upstream permit 64512:3000
2496 ip community-list standard cm-learnt-cust permit 64512:3100
2497 ip community-list standard cm-learnt-peer permit 64512:3200
2499 ! ###################################################################
2500 ! Utility route-maps
2502 ! These utility route-maps generally should not used to permit/deny
2503 ! routes, i.e. they do not have meaning as filters, and hence probably
2504 ! should be used with 'on-match next'. These all finish with an empty
2505 ! permit entry so as not interfere with processing in the caller.
2507 route-map rm-no-export permit 10
2508 set community additive no-export
2509 route-map rm-no-export permit 20
2511 route-map rm-blackhole permit 10
2512 description blackhole, up-pref and ensure it cannot escape this AS
2513 set ip next-hop 127.0.0.1
2514 set local-preference 10
2515 set community additive no-export
2516 route-map rm-blackhole permit 20
2518 ! Set local-pref as requested
2519 route-map rm-prefmod permit 10
2520 match community cm-prefmod-100
2521 set local-preference 100
2522 route-map rm-prefmod permit 20
2523 match community cm-prefmod-200
2524 set local-preference 200
2525 route-map rm-prefmod permit 30
2526 match community cm-prefmod-300
2527 set local-preference 300
2528 route-map rm-prefmod permit 40
2529 match community cm-prefmod-400
2530 set local-preference 400
2531 route-map rm-prefmod permit 50
2533 ! Community actions to take on receipt of route.
2534 route-map rm-community-in permit 10
2535 description check for blackholing, no point continuing if it matches.
2536 match community cm-blackhole
2538 route-map rm-community-in permit 20
2539 match community cm-set-no-export
2542 route-map rm-community-in permit 30
2543 match community cme-prefmod-range
2545 route-map rm-community-in permit 40
2547 ! #####################################################################
2548 ! Community actions to take when advertising a route.
2549 ! These are filtering route-maps,
2551 ! Deny customer routes to upstream with cust-only set.
2552 route-map rm-community-filt-to-upstream deny 10
2553 match community cm-learnt-cust
2554 match community cm-cust-only
2555 route-map rm-community-filt-to-upstream permit 20
2557 ! Deny customer routes to other customers with upstream-only set.
2558 route-map rm-community-filt-to-cust deny 10
2559 match community cm-learnt-cust
2560 match community cm-upstream-only
2561 route-map rm-community-filt-to-cust permit 20
2563 ! ###################################################################
2564 ! The top-level route-maps applied to sessions. Further entries could
2565 ! be added obviously..
2568 route-map rm-cust-in permit 10
2569 call rm-community-in
2571 route-map rm-cust-in permit 20
2572 set community additive 64512:3100
2573 route-map rm-cust-in permit 30
2575 route-map rm-cust-out permit 10
2576 call rm-community-filt-to-cust
2578 route-map rm-cust-out permit 20
2580 ! Upstream transit ASes
2581 route-map rm-upstream-out permit 10
2582 description filter customer prefixes which are marked cust-only
2583 call rm-community-filt-to-upstream
2585 route-map rm-upstream-out permit 20
2586 description only customer routes are provided to upstreams/peers
2587 match community cm-learnt-cust
2590 ! outbound policy is same as for upstream
2591 route-map rm-peer-out permit 10
2592 call rm-upstream-out
2594 route-map rm-peer-in permit 10
2595 set community additive 64512:3200
2598 Example of how to set up a 6-Bone connection.
2602 ! bgpd configuration
2603 ! ==================
2605 ! MP-BGP configuration
2608 bgp router-id 10.0.0.1
2609 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 remote-as `as-number`
2612 network 3ffe:506::/32
2613 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 activate
2614 neighbor 3ffe:1cfa:0:2:2a0:c9ff:fe9e:f56 route-map set-nexthop out
2615 neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 remote-as `as-number`
2616 neighbor 3ffe:1cfa:0:2:2c0:4fff:fe68:a231 route-map set-nexthop out
2619 ipv6 access-list all permit any
2621 ! Set output nexthop address.
2623 route-map set-nexthop permit 10
2624 match ipv6 address all
2625 set ipv6 nexthop global 3ffe:1cfa:0:2:2c0:4fff:fe68:a225
2626 set ipv6 nexthop local fe80::2c0:4fff:fe68:a225
2632 .. include:: routeserver.rst
2634 .. include:: rpki.rst
2636 .. include:: flowspec.rst
2638 .. [#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)
2639 .. [bgp-route-osci-cond] McPherson, D. and Gill, V. and Walton, D., "Border Gateway Protocol (BGP) Persistent Route Oscillation Condition", IETF RFC3345
2640 .. [stable-flexible-ibgp] Flavel, A. and M. Roughan, "Stable and flexible iBGP", ACM SIGCOMM 2009
2641 .. [ibgp-correctness] Griffin, T. and G. Wilfong, "On the correctness of IBGP configuration", ACM SIGCOMM 2002