Services Routers support CoS-based forwarding (CBF) that 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 can specify a particular interface or next hop to carry high-priority traffic while all best-effort traffic takes some other path. CBF allows path selection based on class. 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 selection.
Forwarding policy also allows you to create CoS classification overrides. For IPv4 or IPv6 packets, you can override the incoming CoS classification and assign the packets to a forwarding class based on their input interface, input precedence bits, or destination address. When you override the classification of incoming packets, any mappings you configured for associated precedence bits or incoming interfaces to output transmission queues are ignored.