General QoS and Switching Question

[kylebrogers]

All of the examples I've found for things like LLQ tend to use routed links.  I'm trying to figure out how to deal with things across an L2 trunk.  Specifically, if I have a certain type of traffic that (in cases of trunk congestion) I don't want taking up more than 50% of the trunk's bandwidth, what queuing method should I use and how is it applied (per  VLAN, per trunk interface, etc)?  I'm not looking for someone to write out a config, just a nudge in the right direction so that I know which things to go read up on.  

[Joseph W. Doherty]

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Posting

The reason you see LLQ with routed links, is because it's normally only a feature found on routers.  Switch's "like" feature is often PQ.

Unless you need to treat VLANs (based on their VLAN ID) across a trunk differently, you often just use interface QoS using either L3 ToS or L2 CoS tags.  For example, DSCP EF or CoS 5 might be given PQ treatment regardless of the VLAN ID.

[kylebrogers]

It would be traffic on a VLAN but i can do ingress marking on the few ports that will be on that VLAN.  So you're saying I should tag that traffic and then put that marking in the Priority Queue, then set a bandwidth limit on that queue while everything else will go in the default queue?   All of the queue info then gets applied to the trunk interfaces on both sides of the trunk.  Am I understanding that correctly?