Cisco Systems 4500 PBR Route-Map Processing Logic

35-3
Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 35 Configuring Policy-Based Routing About Policy-Based Routing
route-map rm-test permit 23
match ip address 101 2102
set interface vlan23
!
route-map rm-test deny 24
match ip address 104
set ip next-hop 24.4.4.1
!
route-map rm-test deny 25
match ip address 105
set ip next-hop 25.5.5.1
!
route-map rm-test permit 26
match ip address 2104
set ip next-hop 26.6.6.1
The numbers 21, 22, ... 26 are the sequence numbers of the route-map statements.
The following topics are discussed:
• PBR Route-Map Processing Logic, page 35-3
• PBR Route-Map Processing Logic Example, page 35-4
PBR Route-Map Processing Logic
When a packet is received on an interface configured with a route-map, the forwarding logic processes
each route-map statement according to the sequence number.
If the route-map statement encountered is a route-map...permit statement:
• The packet is matched against the criteria in the match command. This command may refer to an
ACL that may itself have one or more permit and/or deny expressions. The packet is matched against
the expressions in the ACL, and a permit/deny decision is reached.
• If the decision reached is permit, then the PBR logic executes the action specified by the set
command on the packet.
• If the decision reached is deny, then the PBR action (specified in the set command) is not applied.
Instead the processing logic moves forward to look at the next route-map statement in the sequence
(the statement with the next higher sequence number). If no next statement exists, PBR processing
terminates, and the packet is routed using the default IP routing table.
If the route-map statement encountered is a route-map... deny statement:
• The packet is matched against the criteria given in the match command. This command may refer
to an ACL that may itself have one or more permit and/or deny expressions. The packet is matched
against the expressions in the ACL, and a permit/deny decision is reached.
• If the criteria decision is permit, then the PBR processing terminates, and the packet is routed using
the default IP routing table.
• If the criteria decision is deny, then the PBR processing logic moves forward to look at the next
route-map statement in the sequence (the statement with the next higher sequence number). If no
next statement exists, PBR processing terminates, and the packet is routed using the default IP
routing table.
Note The set command has no effect inside a route-map... deny statement.