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QoS on Trunks

We run both VOIP and video over a multi-site WAN MPLS. We have our UCS server in our Michigan site and it operates about 150 phones in our North Carolina site. I have setup QoS on the switchports that the phones are connected to. I have seen that some engineers setup QoS on their trunking ports as well. My question is, should QoS be applied to trunks as well as access ports and if so what benefit does it provide?                  

VIP Expert

Re: QoS on Trunks


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As trunks aren't immune to congestion, you may want QoS on them for reasons similar to other congested ports.

The big difference between a trunk port vs. an access port, the latter may/should deal with initial trust issues.  Hopefully, by the time traffic is on a (transit) trunk, congestion QoS is the only issue.


Re: QoS on Trunks

Hi Brian,
even if I fully agree with Joseph, a common design prefers to over provision trunk capability rather than implementing QoS on the trunk ports. On the other hand, maybe the geographical distance requires particular markings (Voice and Video) and prioritisation in order to reduce the processing and serialisation delays.

Hope this helps

Sent from Cisco Technical Support iPad App


Re: QoS on Trunks

Hi, like Joseph says, the trunk are practically inmune to a congestion.

But, you must configure cos/dscp trust on this port, to avoid that the switch remark the frames or packets.

Good Bye.


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