Question

A network engineer configures policy-based routing on R1 to send traffic from the 10.1.1.0/24 subnet out a secondary ISP link (next hop 203.0.113.2). The route map matches an ACL permitting the source subnet and includes 'set ip next-hop 203.0.113.2'. The route map is applied with 'ip policy route-map PBR-ISP2' on the ingress interface. Users report their traffic is still following the default route out the primary ISP. A traceroute from R1 itself using the source subnet is not possible, but 'show route-map PBR-ISP2' shows 0 matches. What is the most likely cause?

Accepted Answer

The 'ip policy route-map' command was applied to the wrong (egress) interface instead of the interface where the 10.1.1.0/24 traffic enters R1.

Answer

PBR cannot use 'set ip next-hop'; it must use 'set interface' when the next hop is on a different ISP.

Answer

The next hop 203.0.113.2 is not directly connected, so PBR silently ignores the set clause and uses the routing table.

Answer

PBR only processes locally generated traffic, so 'ip policy route-map' should be replaced with 'ip local policy route-map'.