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New Member

route maps

Are these like an access list, can anyone give me a quick easy explanation why we use them and an example ?


New Member

Re: route maps

Yes, they are like access lists except instead of just denying/allowing traffic you can do many more things based on a match. They are much more granular. In this example I simply set the default route, but you can much more.

route-map test permit 10

match ip address 110

set ip default next-hop


route-map test permit 20

match ip address 120

set ip default next-hop


access-list 110 permit ip any

access-list 120 permit ip any

Re: route maps


Route-maps can be used in a variety of ways. They can be used to make policy based routing decisions IE if traffic is from this host then send it here instead. They can be used for changing attributes about packets. IE change the tos, dscp and a couple of other attribuets. They have the ability to be used to change attributes of routing protocols. IE filter bgp neighbors set attributes of routes learned etc.

My experience is the majority of people use them for policy based routing. Here is an example. Lets say I have three interfaces on a router two for internet and a lan connection. My default route sends traffic out serial 1/0 but I have a second connection serial 2/0. I have a bunch of devices on my fastethernet 0/0. I want all my devices to exit my network via s1/0 except a mail server which should use 2/0. I would use a route-map to change the way it exits. Lets say my mail server is at

access-list 100 permit ip host any

route-map test permit 10

match ip address 100

set interface s2/0

route-map test permit 20

interface fastethernet 0/0

ip policy route-map test

The first route-map statement matches our acl 100 which has our mail server and then sends it out the serial 2/0 interface. Our second route-map statement allow the rest of our traffic to go on its merry way without being changed. Without this second statement all other traffic would be denied. By adding the ip policy route-map on the fastethernet interface we actully put the route-map into action for traffic traversing that interface.

Patrick Laidlaw

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