Within large ISP networks, services are typically required from any PE to any PE and can traverse multiple domains. Also, within a service, different traffic classes can coexist, each with specific requirements on latency and jitter.
SR OS provides a comprehensive set of Class Based Forwarding capabilities. Specifically the following can be performed:
Class-based forwarding, in conjunction with ECMP, for incoming unlabeled traffic resolving to an LDP FEC, over IGP IPv4 shortcuts (LER role)
Class-based forwarding, in conjunction with ECMP, for incoming labeled LDP traffic, over IGP IPv4 shortcuts (LSR role)
Class-based forwarding, in conjunction with ECMP, of GRT IPv4/IPv6 prefixes over IGP IPv4 shortcuts
See chapter IP Router Configuration, Section 2.3 in 7450 ESS, 7750 SR, 7950 XRS, and VSR Router Configuration Guide, for a description of this case.
Class-based forwarding, in conjunction with ECMP, of VPN-v4/-v6 prefixes over RSVP-TE or SR-TE
See chapter Virtual Private Routed Network Service, Section 3.2.27 in 7450 ESS, 7750 SR, 7950 XRS, and VSR Layer 3 Services Guide: IES and VPRN, for a description of this case.
IGP IPv4 shortcuts, in all four cases, see MPLS RSVP-TE or SR-TE LSPs.