Example: Configuring CoS-Based Forwarding
Router A has two routes to destination 10.255.71.208 on Router D. One route goes through Router B, and the
other goes through Router C, as shown in Figure 1.
Configure Router A with CoS-based forwarding (CBF) to select Router B for queue 0 and queue 2, and Router C for queue 1 and queue 3.
Figure 1: Sample CoS-Based Forwarding
When you configure CBF with OSPF as the IGP, you must
specify the next hop as an interface name, not as an IPv4 or IPv6
address. The next hops in this example are specified as ge-2/0/0.0 and so-0/3/0.0.
[edit class-of-service]
forwarding-policy {
next-hop-map my_cbf {
forwarding-class be {
next-hop ge-2/0/0.0;
}
forwarding-class ef {
next-hop so-0/3/0.0;
}
forwarding-class af {
next-hop ge-2/0/0.0;
}
forwarding-class nc {
next-hop so-0/3/0.0;
}
}
}
classifiers {
inet-precedence inet {
forwarding-class be {
loss-priority low code-points [ 000 100 ];
}
forwarding-class ef {
loss-priority low code-points [ 001 101 ];
}
forwarding-class af {
loss-priority low code-points [ 010 110 ];
}
forwarding-class nc {
loss-priority low code-points [ 011 111 ];
}
}
}
forwarding-classes {
queue 0 be;
queue 1 ef;
queue 2 af;
queue 3 nc;
}
interfaces {
at-4/2/0 {
unit 0 {
classifiers {
inet-precedence inet;
}
}
}
}
[edit policy-options]
policy-statement cbf {
from {
route-filter 10.255.71.208/32 exact;
}
then cos-next-hop-map my_cbf;
}
[edit routing-options]
graceful-restart;
forwarding-table {
export cbf;
}
[edit interfaces]
traceoptions {
file trace-intf size 5m world-readable;
flag all;
}
so-0/3/0 {
unit 0 {
family inet {
address 10.40.13.1/30;
}
family iso;
family mpls;
}
}
ge-2/0/0 {
unit 0 {
family inet {
address 10.40.12.1/30;
}
family iso;
family mpls;
}
}
at-4/2/0 {
atm-options {
vpi 1 {
maximum-vcs 1200;
}
}
unit 0 {
vci 1.100;
family inet {
address 10.40.11.2/30;
}
family iso;
family mpls;
}
}