Class-of-service (CoS)-based forwarding (CBF) enables you to control next-hop selection based on a packet’s class of service and, in particular, the value of the IP packet’s precedence bits.
For example, you might want to specify a particular interface or next hop to carry high-priority traffic while all best-effort traffic takes some other path. When a routing protocol discovers equal-cost paths, it can pick a path at random or load-balance across the paths through either hash selection or round robin. CBF allows path selection based on class.
To configure CBF properties, include the following statements at the [edit class-of-service] hierarchy level:
- [edit class-of-service]
- forwarding-policy {
-
- next-hop-map map-name {
-
- forwarding-class class-name {
- next-hop [ next-hop-name ];
- lsp-next-hop [ lsp-regular-expression ];
- non-lsp-next-hop;
- discard;
- }
- }
-
- class class-name {
-
- classification-override {
- forwarding-class class-name;
- }
- }
- }
This chapter discusses the following topics:
