Chapter 29
| IP Routing Commands
Policy-based Routing for BGP
– 1000 –
match origin This command sets the originating protocol to match in routing messages. Use the
no form to remove this entry from a route map.
Syntax
match origin {egp | igp | incomplete}
no match origin
egp – Routes learned from exterior gateway protocols.
igp – Routes learned from internal gateway protocols.
incomplete – Routes of uncertain origin.
Command Mode
Route Map
Example
Console(config)#route-map RD permit 8
Console(config-route-map)#match origin igp
Console(config-route-map)#set weight 30
Console(config-route-map)#
match pathlimit This command sets the maximum AS path length allowed for propagation of more
specific prefixes to match in routing messages. Use the no form to remove this
entry from a route map.
Syntax
match pathlimit as as-limit
no match pathlimit as
as-limit – Maximum AS path length. (Range: 1-4294967295)
Command Mode
Route Map
Command Usage
â—† To perform inter-domain traffic engineering, a multi-homed site can advertise
its prefix to all of its neighbors via an aggregate address, and also advertise
more specific prefixes to a subset of its neighbors. The longest match lookup
algorithm then causes traffic for the more specific prefixes to be forwarded to
the subset of neighbors with the more specific prefix.
These longer prefixes may be advertised in addition to an aggregate, even
when the aggregate advertisement is sufficient for basic reachability. This type
of inter-domain traffic engineering is a widely used phenomenon that is
contributing to growth in the size of the global routing table.
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