6 Replies Latest reply on Jan 3, 2014 2:12 PM by david

    QoS for outbound traffic

    tetu04 New Member

      Hello,

       

      One of our customers has 2 T1's that terminate into a NeteVanta 838 (provided by carrier) and provide Ethernet handoffs to the Adtran908e. For quite some time I have been monitoring their calls and I have been noticing a lot of calls receiving lower MOS scores due to packet loss. The site only has around 28 phones and a 3Mbit pipe of dedicated internet access with prioritized voice traffic from the carrier. I have asked the carrier to investigate this issue and explain why packet loss still occurs under all these circumstances. They replied by saying that they manage the download QoS/CoS and we need to manage the upload to guarantee EF. They also said that this customer is bursting 3300bytes within 20 seconds of having the counters cleared at the prem site and this is affecting the calls regardless of voice traffic prioritization. I have enabled the following QoS map on the router and they carrier still notices the bursts.

       

      ip access-list extended qos-match-coredial

        permit udp any  host x.x.x.x ( <-- voice server)

       

      qos map qos-map-coredial 10

        match ip list qos-match-coredial

        priority percent 3

        set dscp 46

       

      interface eth 0/2

        description Connection to OUTSIDE

        speed 100

        ip address  x.x.x.x  x.x.x.x

        media-gateway ip primary

        qos-policy out qos-map-coredial

        no shutdown

       

      The bandwidth of eth 0/2 is set to 100000Kbit, 100Mb/s full-duplex. I just need some suggestions how to improve that QoS map. Should I hardcorde the interface with 3Mbit and then specify the priority percent? Should I use max-reserved-bandwidth and traffic-shape-rate in the config?

       

      Thanks in advance,

      Adrian

        • Re: QoS for outbound traffic
          david Employee

          Tetu04,

           

          Thanks for posting!  Yes, you should generally have a traffic shape rate applied for QoS to any ethernet interface where the bandwidth might bottleneck or be policed upstream.  Below is a configuration you might try.

           

          ip access-list extended qos-match-coredial

            permit udp any  host x.x.x.x ( <-- voice server)

          !

          qos map qos-map-coredial 10

            match ip list qos-match-coredial

            priority percent 50

            set dscp 46

          !

          interface eth 0/2

            qos-policy out qos-map-coredial

            traffic-shape rate 3000000

           

          The priority percentage is up to you, but should be based on the maximum number of concurrent calls you expect, and the voice codec in use.  Feel free to reply on this thread if you have further questions.

           

          Thanks!

          David

            • Re: QoS for outbound traffic
              tetu04 New Member

              David,

               

              I was actually able to get the qos map implemented correctly

               

              qos map qos-map-coredial 10

                match ip list qos-match-coredial

                priority unlimited

                set dscp 46

               

              interface eth 0/2

                description Connection to OUTSIDE

                speed 100

                ip address  207.238.229.154  255.255.255.252

                ip packet-capture glf-traffic-capture

                media-gateway ip primary

                traffic-shape rate 3000000

                max-reserved-bandwidth 100

                qos-policy out qos-map-coredial

                no shutdown

               

              ip access-list extended qos-match-coredial

                permit udp any  host 64.94.197.230

                deny   udp any  any eq 5060

               

              *********************************

               

              greatlakes.ta908e-1#sh qos map interface eth 0/2

              eth 0/2

              qos-policy out: qos-map-coredial

                  

                map entry 10

                   match ip list qos-match-coredial

                   set DSCP value to 46

                   priority bandwidth: unlimited

                     note: since unlimited, other qos bandwidths cannot be assured

                   packets matched: 1143794, bytes matched: 288725884

                 map entry default

                   packets matched: 4492079, bytes matched: 1523550066

                   packets dropped: 97, bytes dropped: 145666

                   5 minute offered rate 1336104 bits/sec, drop rate 0 bits/sec

               

               

              At this point the carrier doesn't see us bursting anymore and they also do not see any EF drops or any packet loss on their local loop. The low MOS calls still exist as before and the customer is still complaining. Is there any information within the Adtran device that I can obtain that provides proof that this issue is a result of the carrier’s network? At this point, the carrier will do nothing about it until I obtain proof. I have copied call examples from nCommand that clearly shows low MOS score, packet loss and reason of degradation but it is still not enough proof. I will go on site and run some packet capture and hopefully some bad calls will appear and I can show them the packet loss in the RTP Stream Analysis. If you have any other suggestions, please advise.


              Thanks,

              Adrian

                • Re: QoS for outbound traffic
                  david Employee

                  Tetu04,

                   

                  The QoS on the Adtran is only going to help with the outbound audio flow.  I think a packet capture, and RTP stream analysis, is a good idea to show exactly how the packets are arriving at the Adtran unit.  Outside of VQM, we often check "show voice quality-stats" for further calls statistics.  We recommend R10.5.3 firmware when using this command since some improvements to the output were made starting with R10.5.0.  A low delay and low jitter network will usually result in no discards, no drops, and average and maximum delay of 50ms.  Below is a link to a document that goes over the statistics in more detail.  See page 15.

                   

                  Understanding Call Quality Statistics in AOS

                   

                  Thanks!

                  David

                  • Re: QoS for outbound traffic
                    david Employee

                    Tetu04,

                     

                    Were you able to get the packet capture and do any RTP analysis within Wireshark?  Feel free to leave an update on here or any additional questions you may have.

                     

                    Thanks,

                    David

                      • Re: QoS for outbound traffic
                        tetu04 New Member

                        Hello David,

                         

                        I went on site and ran multiple packet captures. The packet captures clearly show the packet loss in the RTP stream analysis. The packets cross two different networks until they reach the SIP server provider's voice server. As I mentioned above, I have been working with the T1 provider. I have sent them all the captures and after QoS maps were applied on both ends, they concluded that their network is clean and the packet loss has to happen somewhere upstream. I am in the process of hearing back from the second ISP provider to see what their results indicate.

                  • Re: QoS for outbound traffic
                    david Employee

                    Tetu04,

                     

                    I went ahead and flagged this post as "Assumed Answered".  If any of the responses on this thread assisted you, please mark them as Correct or Helpful as the case may be with the applicable buttons.  This will make them visible and help other members of the community find solutions more easily.  If you still need assistance, I would be more than happy to continue working with you on this - just let me know in a reply.

                     

                    Thanks!

                    David