7 Replies Latest reply on Jan 30, 2014 1:49 PM by noor

    3120 - SIP Proxy Transparent - Breaks BLF (UDP fragmentation)

    jessiebryan New Member

      Hey everyone,

       

      We are testing a NetVanta 3120 with transparent SIP proxy.  Polycom phones behind it, pointed directly to our SBCs.

       

      I noticed that when the Polycom phones are set up for Busy Lamp Fields _and_ UDP signaling, the system fails to process fragmented SIP UDP packets.  If I disable transparent proxy, the Polycom receives BLF correctly.

      I can also change the Polycom to use TCPpreferred - this works by simply by-passing the ALG (which is in errata for the release notes).  The goal is to have Voice Quality Monitoring working, with Polycom phones using BLF.

       

      If I go TCP, then VQM stops reporting stats

      If I go UDP, then BLF fails, but VQM works

       

      The NV3120 is currently running R10.4.0.E (we've tested several older releases as well).

       

      If we put the Polycom phones behind a TA900 system, the BLF works as UDP with VQM.

       

       

       

      The code we use is simply:

        no ip firewall alg sip

        ip access-list extended sip-acl

        ip sip

        ip sip udp 5060

        ip sip tcp 5060

        ip sip proxy

        ip sip proxy transparent

        ip rtp quality-monitoring sip

       

       

      Has anyone seen this issue before? 

       

      In debug mode (debug sip strack level error) we see the following errors:

       

      23:52:56.942 SIP.STACK ERROR  TRANSPORT    TransportUdpEventCallback - sock 42: The UDP buffer is not big enough.

      23:52:57.993 SIP.STACK ERROR  TRANSPORT    TransportUdpEventCallback - sock 42: The UDP buffer is not big enough.

      23:52:59.917 SIP.STACK ERROR  TRANSPORT    TransportUdpEventCallback - sock 42: The UDP buffer is not big enough.

      23:53:03.917 SIP.STACK ERROR  TRANSPORT    TransportUdpEventCallback - sock 42: The UDP buffer is not big enough.