Manipulating Route Updates:
Three ways:
1.using distribute lists.
2.route-maps
3.using administrative distance
Since routing protocols sends all of the routes to its neighbor and you wants some of the route are to be filtered. For this you use any one of the methods for route manipulations.
1. distribute lists:
a. Distribute lists allows you to apply acl filtering to routing updates.
b. can be applied inbound and outbound under a routing process.
c. Works slightly different with OSPF and IS-IS (not outbound filter (All have same link state databases. distribute list only prevent network doesn’t appear in routing table.
configuration:
steps.
1.create an acl
2.apply distribute-list either inbound or outbound
Fig:1
Example:
Tasks:
1. Network 10.501.0 and 10.50.2.0 should not reach R2
2. Network 10.50.3.0 and 10.50.4.0 should not cross R2
(Distribute list is always associated with the ACL)
All of the routers are pre-configured with respective ip and routing protocols.
Task 1 solution:
R1(config)# ip access list standard ROUTE_FILTER R1(config)# deny 10.50.1.0 0.0.0.255 R1(config)# deny 10.50.2.0 0.0.0.255 R1(config)# permit any R1(config)# router rip R1(config-router)# distribute-list ROUTE_FILTER out serial 0/0 If serial0/0 is not used it is applied to all of the interface of the router. (Distribute-list is applied close to the source, It can also be applied in the router R2)
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