WAN issues

HI All,

       I am using cucm 8.6(2) with IP phones,3750 POE switch,3800 Router, core switch, checkpoint firewall involved in the internal LAN network. And Qos is apllied on WAN router for Voice(DSCP EF) ,signalling  packets(DSCP AF31).And we are having 3 clusters with indivdual SUB and PUB cucm.

      Recently i had felt a call disruptions(no Voice heared at both sides but call got connected, no ringback and dialtone was heared).But no phones got unregistered. During  that time i tried to ping my other clusters WAN Routers i experienced some latency and packet drops. I dont know my troubleshooting method is right but i had a assumption that it can be a WAN connectivity issue.

     Now my question is,

1.  I kept trust boundary at Wan Router only, since i didnt get ringback tone itself intra cluster signalling with local CUCM itself not proper right?.

2.  And first troubleshooting i did was pinging  other Wan Routers, by this step i cant able to say that voice packet got dropped, since Ping is ICMP packet(belongs to class default) and VOIP packet and signalling packet is class 5 & 3 in WAN. So how can i prove that voice packet is dropped in WAN?.

3. Is extended ping is needed from one WAN router to other WAN router?If it needed i can have option for TOS value only whether it will be helpful, since my markings are in DSCP ?.

 

 

Please help me out to solve this issue.

Thanks.

 

 

Thanks.

 

Comments

  • Hi,

    If you have QOS policy correctly configured on the WAN links then you should be able to see if there is any drops (outbound) by doing a show policy-map interface.


    What are you pinging call manager? This will drop every 5th ping by design.
    If you are losing pings from router to router over the WAN link then you have a problem and more likely a network issue than a QOS issue.


    It would be worth changing / adding DCSP CS3 for signalling rather than AF31.

    If you need to know if the Service provider is not stripping your QOS then you need to use a sniffer (wireshark) to see what the packets are arriving marked as. Another option is Perfmon (a client app that runs on PC) to do an end to end test, or alternatively setting up ip sla on the routers, you would need to read up on how to set this up.


    Regards

     


    On 2 November 2013 05:31, fred <[email protected]> wrote:

    HI All,

           I am using cucm 8.6(2) with IP phones,3750 POE switch,3800 Router, core switch, checkpoint firewall involved in the internal LAN network. And Qos is apllied on WAN router for Voice(DSCP EF) ,signalling  packets(DSCP AF31).And we are having 3 clusters with indivdual SUB and PUB cucm.

          Recently i had felt a call disruptions(no Voice heared at both sides but call got connected, no ringback and dialtone was heared).But no phones got unregistered. During  that time i tried to ping my other clusters WAN Routers i experienced some latency and packet drops. I dont know my troubleshooting method is right but i had a assumption that it can be a WAN connectivity issue.

         Now my question is,

    1.  I kept trust boundary at Wan Router only, since i didnt get ringback tone itself intra cluster signalling with local CUCM itself not proper right?.

    2.  And first troubleshooting i did was pinging  other Wan Routers, by this step i cant able to say that voice packet got dropped, since Ping is ICMP packet(belongs to class default) and VOIP packet and signalling packet is class 5 & 3 in WAN. So i can prove that voice packet is dropped in WAN?.

    3. Is extended ping is needed from one WAN router to other WAN router?If it needed i can have option for TOS value only whether it will be helpful, since my markings are in DSCP ?.

     

     

    Please help me out to solve this issue.

    Thanks.

     

     

    Thanks.

     





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  • Hello Fred,

     

     

    Quick answers to your questions:

    1. QoS trust settings on the WAN routers do not tell us anything as your architecture is fairly complex.

    Possible points trouble points:

    - Checkpoint Firewall : did you enable packet inspection or whatever they call it in Checkpoint language ? 

    - is QoS enabled on the internal LAN infrastructure (core switch & 3750)?

    - What's the CUCM state ? Any replication issues ?

    Some element is messing with the signaling you just have to find it out by process of elimination. 

     

    2. Use IP SLA to proactively monitor your WAN infrastructure

    http://www.cisco.com/en/US/docs/ios/12_4/ip_sla/configuration/guide/hsvoipj.html

     

    3. If you really need to use ping you definetly have the option of specifying the ToS value.

     

    R2#ping
    Protocol [ip]:
    Target IP address: X.X.X.X
    Repeat count [5]: 
    Datagram size [100]:
    Timeout in seconds [2]:
    Extended commands [n]: y
    Source address or interface:
    Type of service [0]: 0xB8
    Set DF bit in IP header? [no]:

     

    Regards,

    Ovidiu

  • Hi Fred,

    Sorry to hear you are having hard time to troubleshoot the issue. Please consider my advise:

    1. Mute call/ringback tone is a common issue for WAN scenario, most of the issues are related to routing issues. Please make sure the round trip traffic is following the same route. Means, traffic from site A to B should follow the same route as of from site B to site A.

    2. To make sure your firewall is not filtering any port, bypass the traffic for the time being.

    3. Be sure both the phone subnets have route towards each other. Means, phone X should be reachable to phone Y.

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