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Configuring routing policies
Routing policies control routing paths by filtering and modifying routing information. This chapter
describes both IPv4 and IPv6 routing policies.
Overview
Routing policies can filter advertised, received, and redistributed routes, and modify attributes for specific
routes.
To configure a routing policy:
1.
Configure filters based on route attributes, such as destination address and the advertising router's
address.
2.
Create a routing policy and apply filters to the routing policy.
Filters
Routing policies can use the following filters to match routes.
ACL
ACLs include IPv4 ACLs and IPv6 ACLs. An ACL can match the destination or next hop of routes.
For more information about ACLs, see
ACL and QoS Configuration Guide
.
IP prefix list
IP prefix lists include IPv4 prefix lists and IPv6 prefix lists.
An IP prefix list matches the destination address of routes. You can use the
gateway
option to receive
routes only from specific routers. For more information about the
gateway
option, see "
Configuring RIP
"
and "
Configuring OSPF
."
An IP prefix list, identified by name, can contain multiple items. Each item, identified by an index number,
specifies a prefix range to match. An item with a smaller index number is matched first. A route that
matches one item matches the IP prefix list.
AS path list
An AS path list matches the AS_PATH attribute of BGP routes.
For more information about AS path lists, see "
Configuring BGP
."
Community list
A community list matches the COMMUNITY attribute of BGP routes.
For more information about community lists, see "
Configuring BGP
."
Extended community list
An extended community list matches the extended community attribute (Route-Target for VPN and Source
of Origin) of BGP routes.
