ECS4660-28F_Management Guide-R03

C HAPTER 51 | IP Routing Commands
Policy-based Routing for BGP
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EXAMPLE
Console#show ip prefix-list detail rd
ip prefix-list rd:
count: 1, range entries: 0, sequences: 5 - 5
seq 5 deny 10.0.0.0/8 ge 14 le 22 (hit count: 0, refcount: 0)
Console#
show ip prefix-list
summary
This command shows summary information for the specified prefix list.
SYNTAX
show ip prefix-list summary [prefix-list-name]
prefix-list-name – Name of prefix list. (Maximum length: 128
characters, no spaces or other special characters)
COMMAND MODE
Privileged Exec
EXAMPLE
Console#show ip prefix-list summary rd
ip prefix-list rd:
count: 1, range entries: 0, sequences: 5 - 5
Console#
POLICY-BASED ROUTING FOR BGP
This section describes commands used to configure policy-based routing
(PBR) maps for Border Gateway Protocol (BGP).
Policy-based routing is performed before regular routing. PBR inspects
traffic on the interface where the policy is applied and then, based on the
policy, makes some decision. First, the traffic is “matched” according to the
policy. Second, for each match, there is something “set.” What is set could
be that the traffic matches must exit out a different interface, or the traffic
could be given a higher priority, or it could choose to just drop that traffic.
Matching of the traffic is usually done with an ACL (access-control list) that
is referenced by a route-map. In the route-map, if there is a “match” for
the traffic defined in that ACL, then a “set” defines what the administrator
wants to happen to that traffic (prioritize it, route it differently, drop it, or
other actions). Policies can be based on IP address, port numbers,
protocols, or size of packets.
If matching criteria is found and the specified action is to permit the
packet, then it will be forwarded to the next hop based on policy-based
routing. If the action is to deny the packet, normal unicast routing is used
to determine the packet’s next hop, instead of using policy-based routing.
If no matching criteria are found in the route map, normal unicast routing