Route maps provide a means to both filter and/or apply actions to route, hence allowing policy to be applied to routes.
For a route reflector to apply a route-map to reflected routes, be sure to
include bgp route-reflector allow-outbound-policy in router bgp mode.
Route maps are an ordered list of route map entries. Each entry may specify up to four distinct sets of clauses:
.. glossary::
Matching Conditions
A route-map entry may, optionally, specify one or more conditions which
must be matched if the entry is to be considered further, as governed by
the Match Policy. If a route-map entry does not explicitly specify any
matching conditions, then it always matches.
Set Actions
A route-map entry may, optionally, specify one or more Set Actions to set
or modify attributes of the route.
Matching Policy
This specifies the policy implied if the :term:`Matching Conditions` are
met or not met, and which actions of the route-map are to be taken, if
any. The two possibilities are:
- :dfn:`permit`: If the entry matches, then carry out the
:term:`Set Actions`. Then finish processing the route-map, permitting
the route, unless an :term:`Exit Policy` action indicates otherwise.
- :dfn:`deny`: If the entry matches, then finish processing the route-map and
deny the route (return `deny`).
The `Matching Policy` is specified as part of the command which defines
the ordered entry in the route-map. See below.
Call Action
Call to another route-map, after any :term:`Set Actions` have been
carried out. If the route-map called returns `deny` then processing of
the route-map finishes and the route is denied, regardless of the
:term:`Matching Policy` or the :term:`Exit Policy`. If the called
route-map returns `permit`, then :term:`Matching Policy` and :term:`Exit
Policy` govern further behaviour, as normal.
Exit Policy
An entry may, optionally, specify an alternative :dfn:`Exit Policy` to
take if the entry matched, rather than the normal policy of exiting the
route-map and permitting the route. The two possibilities are:
- :dfn:`next`: Continue on with processing of the route-map entries.
- :dfn:`goto N`: Jump ahead to the first route-map entry whose order in
the route-map is >= N. Jumping to a previous entry is not permitted.
The default action of a route-map, if no entries match, is to deny. I.e. a route-map essentially has as its last entry an empty deny entry, which matches all routes. To change this behaviour, one must specify an empty permit entry as the last entry in the route-map.
To summarise the above:
| Match | No Match | |
|---|---|---|
| Permit | action | cont |
| Deny | deny | cont |
- action
- Apply set statements
- If call is present, call given route-map. If that returns a
deny, finish processing and returndeny. - If Exit Policy is next, goto next route-map entry
- If Exit Policy is goto, goto first entry whose order in the list is >= the given order.
- Finish processing the route-map and permit the route.
- deny
- The route is denied by the route-map (return
deny). - cont
- goto next route-map entry
.. clicmd:: show route-map [WORD] [json] Display data about each daemons knowledge of individual route-maps. If WORD is supplied narrow choice to that particular route-map. If the ``json`` option is specified, output is displayed in JSON format.
.. clicmd:: clear route-map counter [WORD] Clear counters that are being stored about the route-map utilization so that subsuquent show commands will indicate since the last clear. If WORD is specified clear just that particular route-map's counters.
.. clicmd:: route-map ROUTE-MAP-NAME (permit|deny) ORDER Configure the `order`'th entry in `route-map-name` with ``Match Policy`` of either *permit* or *deny*.
.. clicmd:: match ip address ACCESS_LIST Matches the specified `access_list`
.. clicmd:: match ip address prefix-list PREFIX_LIST Matches the specified `PREFIX_LIST`
.. clicmd:: match ip address prefix-len 0-32 Matches the specified `prefix-len`. This is a Zebra specific command.
.. clicmd:: match ipv6 address ACCESS_LIST Matches the specified `access_list`
.. clicmd:: match ipv6 address prefix-list PREFIX_LIST Matches the specified `PREFIX_LIST`
.. clicmd:: match ipv6 address prefix-len 0-128 Matches the specified `prefix-len`. This is a Zebra specific command.
.. clicmd:: match ip next-hop ACCESS_LIST Match the next-hop according to the given access-list.
.. clicmd:: match ip next-hop address IPV4_ADDR This is a BGP specific match command. Matches the specified `ipv4_addr`.
.. clicmd:: match ip next-hop prefix-list PREFIX_LIST Match the next-hop according to the given prefix-list.
.. clicmd:: match ipv6 next-hop ACCESS_LIST Match the next-hop according to the given access-list.
.. clicmd:: match ipv6 next-hop address IPV6_ADDR This is a BGP specific match command. Matches the specified `ipv6_addr`.
.. clicmd:: match ipv6 next-hop prefix-list PREFIX_LIST Match the next-hop according to the given prefix-list.
.. clicmd:: match as-path AS_PATH Matches the specified `as_path`.
.. clicmd:: match metric METRIC Matches the specified `metric`.
.. clicmd:: match tag TAG Matches the specified tag value associated with the route. This tag value can be in the range of (1-4294967295).
.. clicmd:: match local-preference METRIC Matches the specified `local-preference`.
.. clicmd:: match community COMMUNITY_LIST Matches the specified `community_list`
.. clicmd:: match peer IPV4_ADDR This is a BGP specific match command. Matches the peer ip address if the neighbor was specified in this manner.
.. clicmd:: match peer IPV6_ADDR This is a BGP specific match command. Matches the peer ipv6 address if the neighbor was specified in this manner.
.. clicmd:: match peer INTERFACE_NAME This is a BGP specific match command. Matches the peer interface name specified if the neighbor was specified in this manner.
.. clicmd:: match peer PEER_GROUP_NAME This is a BGP specific match command. Matches the peer group name specified for the peer in question.
.. clicmd:: match source-protocol PROTOCOL_NAME This is a ZEBRA and BGP specific match command. Matches the originating protocol specified.
.. clicmd:: match source-instance NUMBER This is a ZEBRA specific match command. The number is a range from (0-255). Matches the originating protocols instance specified.
.. clicmd:: match evpn route-type ROUTE_TYPE_NAME This is a BGP EVPN specific match command. It matches to EVPN route-type from type-1 (EAD route-type) to type-5 (Prefix route-type). User can provide in an integral form (1-5) or string form of route-type (i.e ead, macip, multicast, es, prefix).
.. clicmd:: match evpn vni NUMBER This is a BGP EVPN specific match command which matches to EVPN VNI id. The number is a range from (1-6777215).
.. program:: configure
.. clicmd:: set tag TAG Set a tag on the matched route. This tag value can be from (1-4294967295). Additionally if you have compiled with the :option:`--enable-realms` configure option. Tag values from (1-255) are sent to the Linux kernel as a realm value. Then route policy can be applied. See the tc man page. As a note realms cannot currently be used with the installation of nexthops as nexthop groups in the linux kernel.
.. clicmd:: set ip next-hop IPV4_ADDRESS Set the BGP nexthop address to the specified IPV4_ADDRESS. For both incoming and outgoing route-maps.
.. clicmd:: set ip next-hop peer-address Set the BGP nexthop address to the address of the peer. For an incoming route-map this means the ip address of our peer is used. For an outgoing route-map this means the ip address of our self is used to establish the peering with our neighbor.
.. clicmd:: set ip next-hop unchanged Set the route-map as unchanged. Pass the route-map through without changing it's value.
.. clicmd:: set ipv6 next-hop peer-address Set the BGP nexthop address to the address of the peer. For an incoming route-map this means the ipv6 address of our peer is used. For an outgoing route-map this means the ip address of our self is used to establish the peering with our neighbor.
.. clicmd:: set ipv6 next-hop prefer-global For Incoming and Import Route-maps if we receive a v6 global and v6 LL address for the route, then prefer to use the global address as the nexthop.
.. clicmd:: set ipv6 next-hop global IPV6_ADDRESS Set the next-hop to the specified IPV6_ADDRESS for both incoming and outgoing route-maps.
.. clicmd:: set local-preference LOCAL_PREF Set the BGP local preference to `local_pref`.
.. clicmd:: set local-preference +LOCAL_PREF Add the BGP local preference to an existing `local_pref`.
.. clicmd:: set local-preference -LOCAL_PREF Subtract the BGP local preference from an existing `local_pref`.
.. clicmd:: set distance (1-255) Set the Administrative distance to use for the route. This is only locally significant and will not be dispersed to peers.
.. clicmd:: set weight WEIGHT Set the route's weight.
.. clicmd:: set metric <[+|-](1-4294967295)|rtt|+rtt|-rtt> Set the route metric. When used with BGP, set the BGP attribute MED to a specific value. Use `+`/`-` to add or subtract the specified value to/from the existing/MED. Use `rtt` to set the MED to the round trip time or `+rtt`/`-rtt` to add/subtract the round trip time to/from the MED.
.. clicmd:: set min-metric <(0-4294967295)> Set the minimum meric for the route.
.. clicmd:: set max-metric <(0-4294967295)> Set the maximum meric for the route.
.. clicmd:: set aigp-metric <igp-metric|(1-4294967295)> Set the BGP attribute AIGP to a specific value. If ``igp-metric`` is specified, then the value is taken from the IGP protocol, otherwise an arbitrary value.
.. clicmd:: set as-path prepend AS_PATH Set the BGP AS path to prepend.
.. clicmd:: set as-path exclude AS-NUMBER... Drop AS-NUMBER from the BGP AS path.
.. clicmd:: set community COMMUNITY Set the BGP community attribute.
.. clicmd:: set extended-comm-list <EXTCOMMUNITY_LIST_NAME> delete Set BGP extended community list for deletion.
.. clicmd:: set ipv6 next-hop local IPV6_ADDRESS Set the BGP-4+ link local IPv6 nexthop address.
.. clicmd:: set origin ORIGIN <egp|igp|incomplete> Set BGP route origin.
.. clicmd:: set table (1-4294967295) Set the BGP table to a given table identifier
.. clicmd:: set sr-te color (1-4294967295) Set the color of a SR-TE Policy to be applied to a learned route. The SR-TE Policy is uniquely determined by the color and the BGP nexthop.
.. clicmd:: set l3vpn next-hop encapsulation gre Accept L3VPN traffic over GRE encapsulation.
.. clicmd:: call NAME Call route-map `name`. If it returns deny, deny the route and finish processing the route-map.
.. clicmd:: on-match next
.. clicmd:: continue Proceed on to the next entry in the route-map.
.. clicmd:: on-match goto N
.. clicmd:: continue N Proceed processing the route-map at the first entry whose order is >= N
.. clicmd:: route-map ROUTE-MAP-NAME optimization Enable route-map processing optimization for `route-map-name`. The optimization is enabled by default. Instead of sequentially passing through all the route-map indexes until a match is found, the search for the best-match index will be based on a look-up in a prefix-tree. A per-route-map prefix-tree will be constructed for this purpose. The prefix-tree will compose of all the prefixes in all the prefix-lists that are included in the match rule of all the sequences of a route-map.
A simple example of a route-map:
route-map test permit 10
match ip address 10
set local-preference 200
This means that if a route matches ip access-list number 10 it's local-preference value is set to 200.
See :ref:`bgp-configuration-examples` for examples of more sophisticated
usage of route-maps, including of the call action.