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BGP: Configuring Route Maps
Page 28 | Use Route Maps and Other Filters to Filter and Alter BGP and OSPF Routes
Case 1:
Case 2:
Both of these configurations would cause outgoing update packets with empty AS paths to
be dropped, and update packets with an AS path containing 15557 to be allowed.
But, to achieve that in the second case, the AS path list has to be configured to permit empty
paths. This way, the empty path will match the AS path list, and be included into the route
map's action of dropping packets that match the AS path list.
In the second case, the AS path list specifically excludes packets whose AS path contains
15557. Therefore, these packets are not dropped by the first route map entry, and are
permitted by the last (permit all) route map entry.
A community list
Creating A community list is a set of entries that specify which community attribute values are
included in or excluded from the list.
There are two types of community list: standard and expanded.
Standard lists are a just a list of one or more communities. They can be identified by a name,
a number, or the word standard, and are created by using any of the following commands:
If you have more than one community in an entry, separate them with spaces.
awplus(config)#
ip as-path access-list example deny ^$
awplus(config)#
ip as-path access-list example permit 15557
awplus(config)#
router bgp 100
awplus(config-router)#
neighbor 192.168.200.201 filter-list example
out
awplus(config)#
ip as-path access-list example permit ^$
awplus(config)#
ip as-path access-list example deny 15557
awplus(config)#
route-map rmapexample deny 1
awplus(config-route-map)#
match as-path example
awplus(config-route-map)#
route-map rmapexample permit 65535
awplus(config-route-map)#
router bgp 100
awplus(config-router)#
neighbor 192.168.200.201 route-map
rmapexample out
awplus(config)#
ip community-list <1-99> {deny|permit} {aa:xx|
internet|local-as|no-advertise|no-export}
awplus(config)#
ip community-list <list-name> {deny|permit} {aa:xx|
internet|local-as|no-advertise|no-export}
awplus(config)#
ip community-list standard <list-name>
{deny|permit} {aa:xx|internet|local-as|
no-advertise|no-export}