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  • qos question

    I'm new to shoretel, I'm messing around with qos for the first time on a cisco switch. I've been looking through the qos guide that shoretel offers (however the most recent document I can find is from 2006), but I have a question.

    Is it necessary to put qos on each individual cisco port that connects to a phone? Or just for the uplinks.

    Our setup is pretty basic, one Cisco 3845 router at our remote location that connects back to our Data Center via a 50 meg EPL circuit. One of the uplinks on this router connects to a 3560 POE switch which then has about 30 PC's and phones. We are putting out PC's behind our phones, both on different vlans.

    The remote location has a shoregear 90 and the data center houses the shoretel director.

    Thanks in advance.

  • #2

    It is *best* to have qos end to end applied to every port.

    If there is no bandwidth contention, you can get away without ANY QOS. However, it is rare to not have any bandwidth contention.

    We have 2 locations and only have QOS on the router that runs the T1's between the buildings. That being said, we also have our phones on their OWN data network. There are no PC's to flood data out.

    If you dont put it everywhere, and you have a PC that starts spewing data like crazy, your call quality can/will suffer.

    I am a big fan of the separate voice and data network schemes myself. Much less complex to troubleshoot. No PC's to blame.

    Long story short, you should do it right now, instead of chasing your tail later. If you were running gig switches and gig phones, I doubt you would ever have a problem without qos on the switches themselves.


    • #3
      We have 3000 users in 55 different sites, all connected over an MPLS cloud. I have found that QoS needs to be onthe WAN interface and CoS needs to be run on each of the local networks. With Cisco you should only have to tell it to look for DSCP46 and then mark that as whatever your carrier has setup for prioritization.

      On the LAN with CoS I setup class 6 to equal DSCP46 and marked all ports to accept CoS.


      • #4
        Thanks for the responses. We ended up putting qos on the wan links, and we also put the following commands:

        mls qos trust dscp
        auto qos voip trust

        on each interface that had a phone plugged into it.


        • #5
          We work with Cisco alternatives almost exclusively (Juniper/Brocade) so this gets a bit rusty since we are not wrenching on Cisco's all the time. Don't you need to modify the default COS to DSCP mapping as it doesn't come configured to place 46 in the proper queue? I suppose it doesn't really matter in a simple QOS environment but hey, best practices don't kill you.

          mls qos map cos-dscp 0 8 16 24 32 46 48 54