Types of BGP Route Maps

A route map consists of match clauses and set clauses. Match clauses, which consist of a match command, specify the attribute values that determine whether a route matches the route map. Set clauses, which consist of a set command, modify the specified attributes of routes that pass all match clauses in the route map.

BGP route maps can be applied to inbound routes, outbound routes, and redistributed routes. BGP route maps are of two types, those that support both match and set clauses, and those that support only match clauses.

The match-and-set route maps consist of the route maps configured with any of the commands listed in Table 15.

Table 15: Commands That Create Match-and-Set Route Maps

BGP supports the clauses listed in Table 16 for match-and-set route maps.

Table 16: Clauses Supported in BGP Match-and-Set Route Maps

The match-only route maps consist of the route maps configured with any of the commands listed in Table 17. You can use any of the match clauses listed in Table 16 in these route maps. Set clauses have no effect in these route maps.

Table 17: Commands That Create Match-Only Route Maps

BGP does not support the clauses listed in Table 18. However, see Applying Table Maps for exceptions for route maps applied with the table-map command.

Table 18: Clauses Not Supported in BGP Route Maps

match as-path

• Use to match an AS-path access list.
• The implemented weight is based on the first matched AS path.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match as-path pathlist5

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match as-path.

match community

• Use to match a community list.
• Supported for inbound and outbound route maps.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match community comm5

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match community

match distance

• Use to match any routes that have the specified administrative distance.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match distance 25

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match distance.

match extcommunity

• Use to match an extended community list in a route map.
• You can specify one or more extended community list names in a match clause. If you specify more than one extended community list, the lists are logical ORed.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match extcommunity topeka10

• Use the no version to remove the match clause from a route map or a specified value from the match clause.
• See match extcommunity.

match ip address

• Use to match any route that has a destination network number that is permitted by an access list, a prefix list, or a prefix tree, or performs policy routing on packets.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match ip address prefix-tree boston

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match ip address.

match ip next-hop

• Use to match any routes that have a next-hop router address passed by the specified access list, prefix list, or prefix tree.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match ip next-hop 5 192.54.24.1

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match ip next-hop.

match level

• Use to match routes for the specified type.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match level level-1

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match level.

match metric

• Use to match a route for the specified metric value.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match metric 10

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match metric.

match metric-type

• Use to match a route for the specified metric type.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match metric-type external

• Use the no version to delete the match clause from a route map.
• See match metric-type.

match route-type

• Use to match a route for the specified route type.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#match route-type level-1

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match route-type.

match tag

• Use to match the tag value of the destination routing protocol.
• Example

  host1(config)#route-map 1

  host1(config-route-map)#match tag 25

• Use the no version to delete the match clause from a route map or a specified value from the match clause.
• See match tag.

neighbor route-map

• Use to apply a route map to incoming or outgoing routes.
• If you specify an outbound route map, BGP advertises only routes that match at least one section of the route map. For routes that do not match, no further processing takes place with respect to this peer, and those routes are not advertised to this peer. The nonmatching route is still in the BGP RIB and can be sent to other peers depending on the outbound policy applied to those peers.
• If you specify an inbound route map, BGP processes only the received routes that match at least one section of the route map. The nonmatching routes are rejected from entering the local BGP RIB and no further processing takes place.
• A clause with multiple values matches a route having any of the values; that is, the multiple values are logical ORed.
• If you specify a BGP peer group by using the peerGroupName argument, all the members of the peer group inherit the characteristic configured with this command unless it is overridden for a specific peer. However, you cannot configure a member of a peer group to override the inherited peer group characteristic for outbound policy.
• New policy values are applied to all routes that are sent (outbound policy) or received (inbound policy) after you issue the command.

  To apply the new policy to routes that are already present in the BGP routing table, you must use the clear ip bgp command to perform a soft clear or hard clear of the current BGP session.

  Behavior is different for outbound policies configured for peer groups for which you have enabled Adj-RIBs-Out. If you change the outbound policy for such a peer group and want to fill the Adj-RIBs-Out table for that peer group with the results of the new policy, you must use the clear ip bgp peer-group command to perform a hard clear or outbound soft clear of the peer group. You cannot merely perform a hard clear or outbound soft clear for individual peer group members because that causes BGP to resend only the contents of the Adj-RIBs-Out table.

• Example

  host1(config)#rneighbor 192.168.5.34 route-map nyc1 in

• Use the no version to remove the route map.
• See neighbor route-map.

route-map

• Use to define the conditions for redistributing routes from one routing protocol into another, and for filtering or modifying updates sent to or received from peers.
• Each route-map command has a list of match and set commands associated with it.
• The match commands specify the match criteria—the conditions under which redistribution is allowed for the current route map.
• The set commands specify the set actions—the redistribution actions to perform if the criteria enforced by the match commands are set.
• Use route maps when you wish to have detailed control over how routes are redistributed between routing processes.
• The destination routing protocol is the one you specify with the router command.
• The source routing protocol is the one you specify with the redistribute command.
• A clause with multiple values matches a route having any of the values; that is, the multiple values are logical ORed.
• If you specify a BGP peer group by using the peerGroupName argument, all the members of the peer group inherit the characteristic configured with this command unless it is overridden for a specific peer.
• Example

  host1(config)#route-map nyc1 permit 10

• Use the no version to delete the route map.
• See route-map.

set as-path prepend

• Use to modify an AS path for BGP routes by prepending one or more AS numbers or a list of AS numbers to the path list.
• The only global BGP metric available to influence the best-path selection is the AS-path length. By varying the length of the AS path, a BGP speaker can influence the best-path selection by a peer farther away.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set as-path prepend list list10

• Use the no version to delete the set clause from a route map.
• See set as-path prepend.

set comm-list delete

• Use to remove communities specified by the community list from the community attribute of routes matching the route map.
• You can use this command to delete communities only if the community list was created with a single community per list entry as shown in the following sample configuration for router Test:

  host1(config)#ip community-list 1 permit 231:10

  host1(config)#ip community-list 1 permit 231:20

  host1(config)#router bgp 45

  host1(config-router)#neighbor 10.6.2.5 remote-as 5

  host1(config-router)#neighbor 10.6.2.5 route-map indelete in

  host1(config-router)#route-map indelete permit 10

  host1(config-route-map)#set comm-list 1 delete

  Router Test receives the same route from 10.6.2.5 and applies the indelete route map. BGP compares each list entry with the community attribute. A match is found for the list entry 231:10, and this community is deleted from the community attribute. Similarly, a match is found for the list entry of 231:20, and this community is deleted from the community attribute.

• Use the no version to delete the set clause from a route map.
• See set comm-list delete.

set community

• Use to set the community attribute in BGP updates.
• You can specify a community list number in the range 1–4294967295, or in the new community format of AA:NN, or one of the following well-known communities:
  • local-as—Prevents advertisement outside the local AS
  • no-advertise—Prevents advertisement to any peer
  • no-export—Prevents advertisement beyond the BGP confederation boundary
• Alternatively, you can use the list keyword to specify the name of a community list that you previously created with the ip community-list command.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set community no-advertise

• Use the none keyword to remove the community attribute from a route.
• Use the no version to delete the set clause from a route map.
• See set community.

set dampening

• Use to enable BGP route flap dampening only on routes that pass the match clauses of, and are redistributed by, a particular route map.
• BGP creates a dampening parameter block for each unique set of dampening parameters—such as suppress threshold and reuse threshold—used by BGP. For example, if you have a route map that sets the dampening parameters to one set of values for some routes and to another set of values for the remaining routes, BGP uses and stores two dampening parameter blocks, one for each set.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set dampening 5 1000 1500 45 15

• Use the no version to delete the set clause from a route map.
• See set dampening.

set extcommunity

• Use to set the extended community attributes in a route map for BGP updates.
• You can specify a site-of-origin (soo) extended community and a route target (rt) extended community at the same time in a set clause without overwriting the other.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set extcommunity rt 10.10.10.2:325

• Use the no version to delete the set clause from a route map.
• See set extcommunity.

set ip next-hop

• Use to set the next hop attribute of a route that matches a route map.
• This command is not supported for route maps used by the table-map command.
• You can specify an IP address or an interface as the next hop.
• Use the peer-address keyword to have the following effect:
  • On outbound route maps, disables the next hop calculation by setting the next hop to the IP address of the BGP speaker
  • On inbound route maps, overrides any third-party next-hop configuration by setting the next hop to the IP address of the peer
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set ip next-hop 192.56.32.1

• Use the no version to delete the set clause from a route map.
• See set ip next-hop.

set local-preference

• Use to specify a preference value for the AS path.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set local-preference 200

• Use the no version to delete the set clause from a route map.
• See set local-preference.

set metric

• Use to set the metric value—for BGP, the MED—for a route.
• To establish an absolute metric, do not enter a plus or minus sign before the metric value.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set metric 10

• To establish a relative metric, specify a plus or minus sign immediately preceding the metric value. The value is added to or subtracted from the metric of any routes matching the route map. The relative metric value can be in the range 0–4294967295.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set metric -25

• You cannot use both an absolute metric and a relative metric within the same route map sequence. Setting either metric overrides any previously configured value.
• Use the no version to delete the set clause from a route map.
• See set metric.

set metric-type

• Use to set the metric type for a route.
• For BGP, affects all types of route maps. If the route map contains both a set metric-type and a set metric clause, the set metric clause takes precedence. Specifying the internal metric type in a BGP outbound route map, BGP sets the MED of the advertised routes to the IGP cost of the next hop of the advertised route. If the cost of the next hop changes, BGP is not forced to readvertise the route.
• For BGP, you can specify the following:
  • external—Reverts to the normal BGP rules for propagating the MED; this is the BGP default
  • internal—Sets the MED of a received route that is being propagated to an external peer equal to the IGP cost of the indirect next hop
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set metric-type internal

• Use the no version to delete the set clause from a route map.
• See set metric-type.

set origin

• Use to set the BGP origin of the advertised route.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set origin egp

• Use the no version to delete the set clause from a route map.
• See set origin.

set tag

• Use to set the tag value of the destination routing protocol.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set tag 23

• Use the no version to delete the set clause from a route map.
• See set tag.

set weight

• Use to specify the BGP weight for the routing table.
• The weights assigned with the set weight command in a route map override the weights assigned using the neighbor weight and neighbor filter-list weight commands.
• Example

  host1(config)#route-map nyc1 permit 10

  host1(config-route-map)#set weight 200

• Use the no version to delete the set clause from a route map.
• See set weight.

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