Forwarding Policy Options Overview
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, Junos picks 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; } forwarding-class-default { discard; lsp-next-hop [ lsp-regular-expression ]; next-hop [next-hop-name]; non-lsp-next-hop; } } class class-name { classification-override { forwarding-class class-name; } } }
Beginning with
Junos OS Release 17.1R1, QFX10000 Series switches support CoS-based
forwarding. [set class-of-service forwarding-policy class] is not supported on QFX10000 Series switches.
Beginning with Junos
OS Release 17.2, MX routers with MPCs or MS-DPCs, VMX, PTX3000 routers,
PTX5000 routers, and VPTX support configuring CoS-based forwarding
(CBF) for up to 16 forwarding classes. All
other platforms support CBF for up to 8 forwarding classes. To support
up to 16 forwarding classes for CBF on MX routers, enable enhanced-ip at the [edit chassis network-services] hierarchy level.
Enabling enhanced-ip is not necessary on PTX routers to
support 16 forwarding classes for CBF.
Change History Table
Feature support is determined by the platform and release you are using. Use Feature Explorer to determine if a feature is supported on your platform.
[set class-of-service forwarding-policy class] is not supported on QFX10000 Series switches.