Today I applied some wrr-queuing commands to a gigabit interface on a 6748 1 G SFP card.
wrr-queue random-detect min-threshold 1 40 80
wrr-queue random-detect min-threshold 2 40 80
wrr-queue cos-map 1 2 2
wrr-queue cos-map 2 1 3 4
wrr-queue cos-map 2 2 6 7
OK, I applied it because the architectural group at the client has set such a standard for this particular type interface. When I add the configs, the router automatically added the same QoS configs to other interfaces on the card.
Is it because the card is divided into port groups that share the same queueing hardware?
I never saw this behavior before.
Yes, it's documented (somewhat obscurely) here:
Basically, there are some commands (listed in the link above) which only apply to an ASIC and hence all the ports attached to that ASIC.
The "show interfaces capabilities" command will show which ports are on which ASIC.
Your understanding is correct. Since hardware resources are shared between ports, QoS configuration gets applied to all ports in the block(usually 12). You should have seen a message indicating so when you configured
Router(config-if)#wrr-queue cos-map 1 1 1
Propagating cos-map configuration to: Gi2/13 Gi2/14 Gi2/15 Gi2/16 Gi2/17 Gi2/18 Gi2/19 Gi2/20 Gi2/21 Gi2/22 Gi2/23 Gi2/24