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Cisco: Route-maps

One of the main purposes of a route-map in a Cisco router is customize traffic management beyond the boundaries of the routing table, For example create load balancing, or in a different field, applying TAG's on a routes learned by a routing protocol
the structure of the route-map is very simple, it’s a set of rules, each rule has two fields, match and set.

For example a route-map used for policy based routing :
Router (config)# route-map TEST permit 10
Router (config-route-map)# match ip address 100
Router (config-route-map)# set ip next-hop 1.1.1.1
Router (config)# route-map TEST permit 20
Router (config-route-map)# match ip address 200
Router (config-route-map)# set ip next-hop 1.1.1.2
In this example I created a route-map named TEST, in case we have a match on access-list "100" change the next-hop to 1.1.1.1
In case we don’t, moving to rule 20, and there in case we have a match on access-list "200" change the next-hop to 1.1.1.2

In this example we can apply the route-map on the LAN interface, and set part of the network to pass through one line and another part through a different one,
This can be done by anything in the ACL, source or destination IP, Protocol, or port.
To make it more clear the ACL and applying the route-map:
Router (config)#access-list 100 permit ip host 192.168.0.50 any
Router (config)#access-list 100 permit gre any any
Router (config)#access-list 100 permit udp any any eq isakmp
Router (config)# interface FastEthernet 0/0
Router (config-if)#ip policy route-map 
In other words, access-list 100 will match all packets with the one of the following criteria source of 192.168.0.50, GRE protocol, or ISAKMP (UDP port 500)
And I applied the route-map on the LAN interface, FastEthernet 0/0

Another example of using a route-map is applying custom settings to routes learned (or advertised ) by a routing protocol

for example:
Router (config)# route-map BGP-IN permit 10
Router (config-route-map)# match ip address 100
Router (config-route-map)# set tag 10
Router (config)# route-map BGP-IN permit 20
Router (config-route-map)# set tag 20
Router (config)#router bgp 1
Router (config-router)# neighbor 2.2.2.2 remote-as 2
Router (config-router)# neighbor 2.2.2.2 route-map BGP-IN in
In this example I used a route-map and applied it on a BGP peer 2.2.2.2 (on the incoming routes) ,
the first rule applies tag '10' to any route matched in ACL 100 and tag '20' to any other ( notice that if no match statement is configured the route-map will match everything)

this should cover basic route-map configuration


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11 comments:

  1. But can you use one route map on multiple vlan interfaces, with the route-mail setting next hop and the match pointing to an ACL selecting traffic from both vlan interfaces?

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    Replies
    1. Sure, you can use the same Route-map on as many interfaces as you wish.
      If you want you can match traffic of both interfaces or even creating a route-map with no 'Match' statement and it will be match all.

      Delete
  2. Thanx very clear concept

    ReplyDelete
  3. Thanks bro. u have explained very clearly.

    ReplyDelete
  4. good example, one confusion though can we apply same route-map policy to multiple interfaces

    ReplyDelete
  5. hi , can we apply route-map to vlan interfaces

    ReplyDelete
  6. Router Configuration may be delivered by the different technologies depending on the situation. For example, Router Configuration can be addressed using configuration, wireless setup, hardware installation. This customer services for the worldwide user delivered by www.bestbuysystems.us/routers.

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