doc: spelling fixes

[mirror_frr.git] / doc / user / zebra.rst

.. _zebra:

*****
Zebra
*****

*zebra* is an IP routing manager. It provides kernel routing
table updates, interface lookups, and redistribution of routes between
different routing protocols.

.. _invoking-zebra:

Invoking zebra
==============

Besides the common invocation options (:ref:`common-invocation-options`), the
*zebra* specific invocation options are listed below.

.. program:: zebra

.. option:: -b, --batch

   Runs in batch mode. *zebra* parses configuration file and terminates
   immediately.

.. option:: -k, --keep_kernel

   When zebra starts up, don't delete old self inserted routes.

.. option:: -r, --retain

   When program terminates, retain routes added by zebra.

.. program:: configure

.. _interface-commands:

Interface Commands
==================

.. _standard-commands:

Standard Commands
-----------------

.. index:: interface IFNAME

.. clicmd:: interface IFNAME

.. index:: shutdown

.. clicmd:: shutdown
.. index:: no shutdown

.. clicmd:: no shutdown

   Up or down the current interface.

.. index:: ip address ADDRESS/PREFIX

.. clicmd:: ip address ADDRESS/PREFIX
.. index:: ipv6 address ADDRESS/PREFIX

.. clicmd:: ipv6 address ADDRESS/PREFIX
.. index:: no ip address ADDRESS/PREFIX

.. clicmd:: no ip address ADDRESS/PREFIX
.. index:: no ipv6 address ADDRESS/PREFIX

.. clicmd:: no ipv6 address ADDRESS/PREFIX

   Set the IPv4 or IPv6 address/prefix for the interface.

.. index:: ip address LOCAL-ADDR peer PEER-ADDR/PREFIX

.. clicmd:: ip address LOCAL-ADDR peer PEER-ADDR/PREFIX
.. index:: no ip address LOCAL-ADDR peer PEER-ADDR/PREFIX

.. clicmd:: no ip address LOCAL-ADDR peer PEER-ADDR/PREFIX

   Configure an IPv4 Point-to-Point address on the interface. (The concept of
   PtP addressing does not exist for IPv6.)

   `local-addr` has no subnet mask since the local side in PtP addressing is
   always a single (/32) address. `peer-addr/prefix` can be an arbitrary subnet
   behind the other end of the link (or even on the link in Point-to-Multipoint
   setups), though generally /32s are used.

.. index:: ip address ADDRESS/PREFIX secondary

.. clicmd:: ip address ADDRESS/PREFIX secondary
.. index:: no ip address ADDRESS/PREFIX secondary

.. clicmd:: no ip address ADDRESS/PREFIX secondary

   Set the secondary flag for this address. This causes ospfd to not treat the
   address as a distinct subnet.

.. index:: description DESCRIPTION ...

.. clicmd:: description DESCRIPTION ...

   Set description for the interface.

.. index:: multicast

.. clicmd:: multicast
.. index:: no multicast

.. clicmd:: no multicast

   Enable or disables multicast flag for the interface.

.. index:: bandwidth (1-10000000)

.. clicmd:: bandwidth (1-10000000)
.. index:: no bandwidth (1-10000000)

.. clicmd:: no bandwidth (1-10000000)

   Set bandwidth value of the interface in kilobits/sec. This is for
   calculating OSPF cost. This command does not affect the actual device
   configuration.

.. index:: link-detect

.. clicmd:: link-detect
.. index:: no link-detect

.. clicmd:: no link-detect

   Enable/disable link-detect on platforms which support this. Currently only
   Linux and Solaris, and only where network interface drivers support
   reporting link-state via the ``IFF_RUNNING`` flag.

.. _link-parameters-commands:

Link Parameters Commands
------------------------

.. index:: link-params
.. clicmd:: link-params

.. index:: no link-param
.. clicmd:: no link-param

   Enter into the link parameters sub node. At least 'enable' must be set to
   activate the link parameters, and consequently Traffic Engineering on this
   interface. MPLS-TE must be enable at the OSPF
   (:ref:`ospf-traffic-engineering`) or ISIS (:ref:`isis-traffic-engineering`)
   router level in complement to this.  Disable link parameters for this
   interface.

   Under link parameter statement, the following commands set the different TE values:

.. index:: link-params [enable]
.. clicmd:: link-params [enable]

   Enable link parameters for this interface.

.. index:: link-params [metric (0-4294967295)]
.. clicmd:: link-params [metric (0-4294967295)]

.. index:: link-params max-bw BANDWIDTH
.. clicmd:: link-params max-bw BANDWIDTH

.. index:: link-params max-rsv-bw BANDWIDTH
.. clicmd:: link-params max-rsv-bw BANDWIDTH

.. index:: link-params unrsv-bw (0-7) BANDWIDTH
.. clicmd:: link-params unrsv-bw (0-7) BANDWIDTH

.. index:: link-params admin-grp BANDWIDTH
.. clicmd:: link-params admin-grp BANDWIDTH

   These commands specifies the Traffic Engineering parameters of the interface
   in conformity to RFC3630 (OSPF) or RFC5305 (ISIS).  There are respectively
   the TE Metric (different from the OSPF or ISIS metric), Maximum Bandwidth
   (interface speed by default), Maximum Reservable Bandwidth, Unreserved
   Bandwidth for each 0-7 priority and Admin Group (ISIS) or Resource
   Class/Color (OSPF).

   Note that BANDIWDTH is specified in IEEE floating point format and express
   in Bytes/second.

.. index::  link-param delay (0-16777215) [min (0-16777215) | max (0-16777215)]
.. clicmd:: link-param delay (0-16777215) [min (0-16777215) | max (0-16777215)]

.. index::  link-param delay-variation (0-16777215)
.. clicmd:: link-param delay-variation (0-16777215)

.. index::  link-param packet-loss PERCENTAGE
.. clicmd:: link-param packet-loss PERCENTAGE

.. index::  link-param res-bw BANDWIDTH
.. clicmd:: link-param res-bw BANDWIDTH

.. index::  link-param ava-bw BANDWIDTH
.. clicmd:: link-param ava-bw BANDWIDTH

.. index::  link-param use-bw BANDWIDTH
.. clicmd:: link-param use-bw BANDWIDTH

   These command specifies additional Traffic Engineering parameters of the
   interface in conformity to draft-ietf-ospf-te-metrics-extension-05.txt and
   draft-ietf-isis-te-metrics-extension-03.txt. There are respectively the
   delay, jitter, loss, available bandwidth, reservable bandwidth and utilized
   bandwidth.

   Note that BANDWIDTH is specified in IEEE floating point format and express
   in Bytes/second.  Delays and delay variation are express in micro-second
   (µs). Loss is specified in PERCENTAGE ranging from 0 to 50.331642% by step
   of 0.000003.

.. index:: link-param neighbor <A.B.C.D> as (0-65535)
.. clicmd:: link-param neighbor <A.B.C.D> as (0-65535)

.. index:: link-param no neighbor
.. clicmd:: link-param no neighbor

   Specifies the remote ASBR IP address and Autonomous System (AS) number
   for InterASv2 link in OSPF (RFC5392).  Note that this option is not yet
   supported for ISIS (RFC5316).

.. _static-route-commands:

Static Route Commands
=====================

Static routing is a very fundamental feature of routing technology. It
defines static prefix and gateway.

.. index:: ip route NETWORK GATEWAY
.. clicmd:: ip route NETWORK GATEWAY

   NETWORK is destination prefix with format of A.B.C.D/M. GATEWAY is gateway
   for the prefix. When GATEWAY is A.B.C.D format. It is taken as a IPv4
   address gateway. Otherwise it is treated as an interface name. If the
   interface name is ``null0`` then zebra installs a blackhole route.

   Some example configuration:

   .. code-block:: frr

      ip route 10.0.0.0/8 10.0.0.2
      ip route 10.0.0.0/8 ppp0
      ip route 10.0.0.0/8 null0

   First example defines 10.0.0.0/8 static route with gateway 10.0.0.2.
   Second one defines the same prefix but with gateway to interface ppp0. The
   third install a blackhole route.

.. index:: ip route NETWORK NETMASK GATEWAY
.. clicmd:: ip route NETWORK NETMASK GATEWAY

   This is alternate version of above command. When NETWORK is
   A.B.C.D format, user must define NETMASK value with A.B.C.D
   format. GATEWAY is same option as above command.

   .. code-block:: frr

      ip route 10.0.0.0 255.255.255.0 10.0.0.2
      ip route 10.0.0.0 255.255.255.0 ppp0
      ip route 10.0.0.0 255.255.255.0 null0


   These statements are equivalent to those in the previous example.

.. index:: ip route NETWORK GATEWAY DISTANCE
.. clicmd:: ip route NETWORK GATEWAY DISTANCE

   Installs the route with the specified distance.

Multiple nexthop static route:

.. code-block:: frr

   ip route 10.0.0.1/32 10.0.0.2
   ip route 10.0.0.1/32 10.0.0.3
   ip route 10.0.0.1/32 eth0


If there is no route to 10.0.0.2 and 10.0.0.3, and interface eth0
is reachable, then the last route is installed into the kernel.

If zebra has been compiled with multipath support, and both 10.0.0.2 and
10.0.0.3 are reachable, zebra will install a multipath route via both
nexthops, if the platform supports this.

::

   zebra> show ip route
   S>  10.0.0.1/32 [1/0] via 10.0.0.2 inactive
       via 10.0.0.3 inactive
     *       is directly connected, eth0


.. code-block:: frr

   ip route 10.0.0.0/8 10.0.0.2
   ip route 10.0.0.0/8 10.0.0.3
   ip route 10.0.0.0/8 null0 255


This will install a multihop route via the specified next-hops if they are
reachable, as well as a high-metric blackhole route, which can be useful to
prevent traffic destined for a prefix to match less-specific routes (e.g.
default) should the specified gateways not be reachable. E.g.:

::

   zebra> show ip route 10.0.0.0/8
   Routing entry for 10.0.0.0/8
     Known via "static", distance 1, metric 0
       10.0.0.2 inactive
       10.0.0.3 inactive

   Routing entry for 10.0.0.0/8
     Known via "static", distance 255, metric 0
       directly connected, Null0


.. index:: ipv6 route NETWORK GATEWAY
.. clicmd:: ipv6 route NETWORK GATEWAY

.. index:: ipv6 route NETWORK GATEWAY DISTANCE
.. clicmd:: ipv6 route NETWORK GATEWAY DISTANCE

   These behave similarly to their ipv4 counterparts.

.. index:: ipv6 route NETWORK from SRCPREFIX GATEWAY
.. clicmd:: ipv6 route NETWORK from SRCPREFIX GATEWAY

.. index:: ipv6 route NETWORK from SRCPREFIX GATEWAY DISTANCE
.. clicmd:: ipv6 route NETWORK from SRCPREFIX GATEWAY DISTANCE

   Install a static source-specific route. These routes are currently supported
   on Linux operating systems only, and perform AND matching on packet's
   destination and source addresses in the kernel's forwarding path. Note that
   destination longest-prefix match is "more important" than source LPM, e.g.
   *"2001:db8:1::/64 from 2001:db8::/48"* will win over
   *"2001:db8::/48 from 2001:db8:1::/64"* if both match.

.. index:: table TABLENO
.. clicmd:: table TABLENO

   Select the primary kernel routing table to be used. This only works
   for kernels supporting multiple routing tables (like GNU/Linux 2.2.x
   and later). After setting TABLENO with this command,
   static routes defined after this are added to the specified table.

.. _multicast-rib-commands:

Multicast RIB Commands
======================

The Multicast RIB provides a separate table of unicast destinations which
is used for Multicast Reverse Path Forwarding decisions. It is used with
a multicast source's IP address, hence contains not multicast group
addresses but unicast addresses.

This table is fully separate from the default unicast table. However,
RPF lookup can include the unicast table.

WARNING: RPF lookup results are non-responsive in this version of FRR,
i.e. multicast routing does not actively react to changes in underlying
unicast topology!

.. index:: ip multicast rpf-lookup-mode MODE
.. clicmd:: ip multicast rpf-lookup-mode MODE

.. index:: no ip multicast rpf-lookup-mode [MODE]
.. clicmd:: no ip multicast rpf-lookup-mode [MODE]

   MODE sets the method used to perform RPF lookups. Supported modes:

   urib-only
      Performs the lookup on the Unicast RIB. The Multicast RIB is never used.

   mrib-only
      Performs the lookup on the Multicast RIB. The Unicast RIB is never used.

   mrib-then-urib
      Tries to perform the lookup on the Multicast RIB. If any route is found,
      that route is used. Otherwise, the Unicast RIB is tried.

   lower-distance
      Performs a lookup on the Multicast RIB and Unicast RIB each. The result
      with the lower administrative distance is used;  if they're equal, the
      Multicast RIB takes precedence.

   longer-prefix
      Performs a lookup on the Multicast RIB and Unicast RIB each. The result
      with the longer prefix length is used;  if they're equal, the
      Multicast RIB takes precedence.

      The `mrib-then-urib` setting is the default behavior if nothing is
      configured. If this is the desired behavior, it should be explicitly
      configured to make the configuration immune against possible changes in
      what the default behavior is.

.. warning::
   Unreachable routes do not receive special treatment and do not cause
   fallback to a second lookup.

.. index:: show ip rpf ADDR
.. clicmd:: show ip rpf ADDR

   Performs a Multicast RPF lookup, as configured with ``ip multicast
   rpf-lookup-mode MODE``. ADDR specifies the multicast source address to look
   up.

   ::

      > show ip rpf 192.0.2.1
      Routing entry for 192.0.2.0/24 using Unicast RIB

      Known via "kernel", distance 0, metric 0, best
      * 198.51.100.1, via eth0


   Indicates that a multicast source lookup for 192.0.2.1 would use an
   Unicast RIB entry for 192.0.2.0/24 with a gateway of 198.51.100.1.

.. index:: show ip rpf
.. clicmd:: show ip rpf

   Prints the entire Multicast RIB. Note that this is independent of the
   configured RPF lookup mode, the Multicast RIB may be printed yet not
   used at all.

.. index:: ip mroute PREFIX NEXTHOP [DISTANCE]
.. clicmd:: ip mroute PREFIX NEXTHOP [DISTANCE]

.. index:: no ip mroute PREFIX NEXTHOP [DISTANCE]
.. clicmd:: no ip mroute PREFIX NEXTHOP [DISTANCE]

   Adds a static route entry to the Multicast RIB. This performs exactly as the
   ``ip route`` command, except that it inserts the route in the Multicast RIB
   instead of the Unicast RIB.

.. _zebra-route-filtering:

zebra Route Filtering
=====================

Zebra supports :dfn:`prefix-list` s and :ref:`route-map` s to match routes
received from other FRR components. The permit/deny facilities provided by
these commands can be used to filter which routes zebra will install in the
kernel.

.. index:: ip protocol PROTOCOL route-map ROUTEMAP
.. clicmd:: ip protocol PROTOCOL route-map ROUTEMAP

   Apply a route-map filter to routes for the specified protocol. PROTOCOL can
   be **any** or one of

   - system,
   - kernel,
   - connected,
   - static,
   - rip,
   - ripng,
   - ospf,
   - ospf6,
   - isis,
   - bgp,
   - hsls.

.. index:: set src ADDRESS
.. clicmd:: set src ADDRESS

   Within a route-map, set the preferred source address for matching routes
   when installing in the kernel.


The following creates a prefix-list that matches all addresses, a route-map
that sets the preferred source address, and applies the route-map to all
*rip* routes.

.. code-block:: frr

   ip prefix-list ANY permit 0.0.0.0/0 le 32
   route-map RM1 permit 10
        match ip address prefix-list ANY
        set src 10.0.0.1

   ip protocol rip route-map RM1


.. _zebra-fib-push-interface:

zebra FIB push interface
========================

Zebra supports a 'FIB push' interface that allows an external
component to learn the forwarding information computed by the FRR
routing suite. This is a loadable module that needs to be enabled
at startup as described in :ref:`loadable-module-support`.

In FRR, the Routing Information Base (RIB) resides inside
zebra. Routing protocols communicate their best routes to zebra, and
zebra computes the best route across protocols for each prefix. This
latter information makes up the Forwarding Information Base
(FIB). Zebra feeds the FIB to the kernel, which allows the IP stack in
the kernel to forward packets according to the routes computed by
FRR. The kernel FIB is updated in an OS-specific way. For example,
the `Netlink` interface is used on Linux, and route sockets are
used on FreeBSD.

The FIB push interface aims to provide a cross-platform mechanism to
support scenarios where the router has a forwarding path that is
distinct from the kernel, commonly a hardware-based fast path. In
these cases, the FIB needs to be maintained reliably in the fast path
as well. We refer to the component that programs the forwarding plane
(directly or indirectly) as the Forwarding Plane Manager or FPM.

The FIB push interface comprises of a TCP connection between zebra and
the FPM. The connection is initiated by zebra -- that is, the FPM acts
as the TCP server.

The relevant zebra code kicks in when zebra is configured with the
:option:`--enable-fpm` flag. Zebra periodically attempts to connect to
the well-known FPM port. Once the connection is up, zebra starts
sending messages containing routes over the socket to the FPM. Zebra
sends a complete copy of the forwarding table to the FPM, including
routes that it may have picked up from the kernel. The existing
interaction of zebra with the kernel remains unchanged -- that is, the
kernel continues to receive FIB updates as before.

The encapsulation header for the messages exchanged with the FPM is
defined by the file :file:`fpm/fpm.h` in the frr tree. The routes
themselves are encoded in Netlink or protobuf format, with Netlink
being the default.

Protobuf is one of a number of new serialization formats wherein the
message schema is expressed in a purpose-built language. Code for
encoding/decoding to/from the wire format is generated from the
schema. Protobuf messages can be extended easily while maintaining
backward-compatibility with older code. Protobuf has the following
advantages over Netlink:

- Code for serialization/deserialization is generated automatically. This
  reduces the likelihood of bugs, allows third-party programs to be integrated
  quickly, and makes it easy to add fields.
- The message format is not tied to an OS (Linux), and can be evolved
  independently.

As mentioned before, zebra encodes routes sent to the FPM in Netlink
format by default. The format can be controlled via the FPM module's
load-time option to zebra, which currently takes the values `Netlink`
and `protobuf`.

The zebra FPM interface uses replace semantics. That is, if a 'route
add' message for a prefix is followed by another 'route add' message,
the information in the second message is complete by itself, and
replaces the information sent in the first message.

If the connection to the FPM goes down for some reason, zebra sends
the FPM a complete copy of the forwarding table(s) when it reconnects.

zebra Terminal Mode Commands
============================

.. index:: show ip route
.. clicmd:: show ip route

   Display current routes which zebra holds in its database.

::

    Router# show ip route
    Codes: K - kernel route, C - connected, S - static, R - RIP,
     B - BGP * - FIB route.

    K* 0.0.0.0/0        203.181.89.241
    S  0.0.0.0/0        203.181.89.1
    C* 127.0.0.0/8      lo
    C* 203.181.89.240/28      eth0


.. index:: show ipv6 route
.. clicmd:: show ipv6 route

.. index:: show interface
.. clicmd:: show interface

.. index:: show ip prefix-list [NAME]
.. clicmd:: show ip prefix-list [NAME]

.. index:: show route-map [NAME]
.. clicmd:: show route-map [NAME]

.. index:: show ip protocol
.. clicmd:: show ip protocol

.. index:: show ipforward
.. clicmd:: show ipforward

   Display whether the host's IP forwarding function is enabled or not.
   Almost any UNIX kernel can be configured with IP forwarding disabled.
   If so, the box can't work as a router.

.. index:: show ipv6forward
.. clicmd:: show ipv6forward

   Display whether the host's IP v6 forwarding is enabled or not.

.. index:: show zebra
.. clicmd:: show zebra

   Display various statistics related to the installation and deletion
   of routes, neighbor updates, and LSP's into the kernel.

.. index:: show zebra fpm stats
.. clicmd:: show zebra fpm stats

   Display statistics related to the zebra code that interacts with the
   optional Forwarding Plane Manager (FPM) component.

.. index:: clear zebra fpm stats
.. clicmd:: clear zebra fpm stats

   Reset statistics related to the zebra code that interacts with the
   optional Forwarding Plane Manager (FPM) component.