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, you can include the following statements at the [edit class-of-service] hierarchy level of the configuration:
- [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: