Dell N3200-ON Networking N-Series Switches User Guide version 6.8.0 - Page 679

Policy-Based Routing In contemporary inter-networks, network administrators often need to implement packet forwarding/routing according to specific organizational policies. Policy-Based Routing (PBR) exactly fits this purpose. Policy-Based Routing provides a flexible mechanism to implement solutions where organizational constraints dictate that traffic be routed through specific network paths. PBR does not affect route redistribution that occurs via routing protocols. PBR is a true routing policy solution. The packet TTL is decremented in PBR-routed packets. The destination MAC is rewritten in PBR-routed packets. ARP lookups are sent when required for unresolved next-hop addresses. Configuring PBR consists of installing a route-map with match and set commands and then applying the corresponding route-map to the routing VLAN interface. IP routing must be enabled on the interfaces by assigning IP addresses to the VLAN interfaces, assigning the VLANs to physical interfaces, and enabling IP routing globally. Packet Classification Route-maps may specify multiple packet attributes in match statements. These attributes can be matched through a "match" clause based on length of the packet or a "match" clause linked with up to 16 ACLs. The match attributes listed below for each ACL type indicate the criteria used to classify Layer-3 routed traffic for PBR. At least one of the listed attributes must be present in the ACL of the given type: • VLAN tag (implicitly added) • MAC access list (match mac-list) - Source MAC address - 802.1p priority • IP access list (match ip address) - Source or destination IP address • Protocol ID field in the IP header • L3 packet length in the IP header (match length) Access Control Lists 679