Configuring Class-of-Service 1129
Continuing this example, the egress port 1/0/8 is configured for strict priority
on queue 6, and a weighted scheduling scheme is configured for queues 5-0.
Assuming queue 5 has a higher weighting than queue 1 (relative weight
values shown as a percentage, with 0% indicating the bandwidth is not
guaranteed), the queue service order is 6 followed by 5 followed by 1.
Assuming each queue unloads all packets shown in the diagram, the packet
transmission order as seen on the network leading out of Port 1/0/8 is B, A, D,
C. Thus, packet B, with its higher user precedence than the others, is able to
work its way through the device with minimal delay and is transmitted ahead
of the other packets at the egress port.
The following commands configure Port 10 (ingress interface) and Port 8
(egress interface).
1
Configure the Trust mode for Port 10.
console#config
console(config)#interface gigabitethernet 1/0/10
console(config-if-Gi1/0/10)#classofservice trust
dot1p
2
For Port 10, configure t
he 802.1p user priority 3
to send the packet to
queue 5 instead of the default queue (queue 3).
console(config-if-Gi1/0/10)#classofservice dot1p-
mapping 3 5
3
For Port 10, specify that untagged VLAN packets should have a default
priority of 2.
console(config-if-Gi1/0/10)#vlan priority 2
console(config-if-Gi1/0/10)#exit
4
For Port 8, the egress port, configure a weighted scheduling scheme for
queues 5-0.
console(config)#interface gigabitethernet 1/0/8
console(config-if-Gi1/0/8)#cos-queue min-
bandwidth 0 0 5 5 10 20 40
5
Configure Port 8 to have strict priority on queue 6.
console(config-if-Gi1/0/8)#cos-queue strict 6
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