Incoming And Outgoing Route Maps; Precedence; Configuration Example - Lenovo CN4093 Application Manual

Incoming and Outgoing Route Maps

Precedence

Configuration Example

1. Define network filter.
2. (Optional) Define the criteria for the access list and enable it.
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You can have two types of route maps: incoming and outgoing. A BGP peer router
can be configured to support up to eight route maps in the incoming route map list
and outgoing route map list.
If a route map is not configured in the incoming route map list, the router imports
all BGP updates. If a route map is configured in the incoming route map list, the
router ignores all unmatched incoming updates. If you set the action to deny, you
must add another route map to permit all unmatched updates.
Route maps in an outgoing route map list behave similar to route maps in an
incoming route map list. If a route map is not configured in the outgoing route
map list, all routes are advertised or permitted. If a route map in the outgoing route
map list is set to permit, matched routes are advertised and unmatched routes are
ignored.
You can set a priority to a route map by specifying a precedence value with the
following commands:
CN 4093(config)# route-map <map number>
CN 4093(config-route-map)# precedence <1-255>
CN 4093(config-route-map)# exit
The smaller the value the higher the precedence. If two route maps have the same
precedence value, the smaller number has higher precedence.
To configure route maps, you need to do the following:
CN 4093(config)# ip match-address 1 <IPv4 address> <IPv4 subnet mask>
CN 4093(config)# ip match-address 1 enable
Enter a filter number from 1 to 256. Specify the IPv4 address and subnet mask of
the network that you want to match. Enable the network filter. You can distribute
up to 256 network filters among 32 route maps each containing eight access lists.
Specify the access list and associate the network filter number configured in Step 1.
CN 4093(config)# route-map 1
CN 4093(config-route-map)# access-list 1 match-address 1
CN 4093(config-route-map)# access-list 1 metric <metric value>
CN 4093(config-route-map)# access-list 1 action deny
CN 4093(config-route-map)# access-list 1 enable
(Select a route map)
(Specify a precedence)
Chapter 29: Border Gateway Protocol
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