Connectivity Guide

Route-maps
Route-maps are a series of commands that contain a matching criterion and action. They change the packets meeting the matching
criterion. ACLs and prex-lists can only drop or forward the packet or trac while route-maps process routes for route redistribution. For
example, use a route-map to lter only specic routes and to add a metric.
• Route-maps also have an implicit deny. Unlike ACLs and prex-lists where the packet or trac drops, if a route does not match the
route-map conditions, the route does not redistribute.
• Route-maps process routes for route redistribution. For example, to add a metric, a route-map can lter only specic routes. If the route
does not match the conditions, the route-map decides where the packet or trac drops. The route does not redistribute if it does not
match.
• Route-maps use commands to decide what to do with trac. To remove the match criteria in a route-map, use the no match
command.
• In a BGP route-map, if you repeat the same match statements; for example, a match metric, with dierent values in the same sequence
number, only the last match and set values are taken into account.
Congure match metric
OS10(config)# route-map hello
OS10(conf-route-map)# match metric 20
View route-map
OS10(conf-route-map)# do show route-map
route-map hello, permit, sequence 10
Match clauses:
metric 20
Change match
OS10(conf-route-map)# match metric 30
View updated route-map
OS10(conf-route-map)# do show route-map
route-map hello, permit, sequence 10
Match clauses:
metric 30
To lter the routes for redistribution, combine route-maps and IP prex lists. If the route or packet matches the congured criteria, OS10
processes the route based on the permit or deny conguration of the prex list.
When a route-map and a prex list combine:
• For a route map with the permit action:
– If a route matches a prex-list set to deny, the route is denied
– If a route matches a prex-list set to permit, the route is permitted and any set of actions apply
• For a route map with the deny action:
– If a route matches a prex-list set to deny, the route is denied
– If a route matches a prex-list set to permit, the route is permitted and any set of actions apply
View both IP prex-list and route-map conguration
OS10(conf-router-bgp-neighbor-af)# do show ip prefix-list
ip prefix-list p1:
seq 1 deny 10.1.1.0/24
seq 10 permit 0.0.0.0/0 le 32
ip prefix-list p2:
seq 1 permit 10.1.1.0/24
seq 10 permit 0.0.0.0/0 le 32
Access Control Lists
701