9 Replies Latest reply on Aug 31, 2017 1:41 PM by curthowland

    SRV records for SBC failover

    curthowland New Member

      I've got two SBCs and would like to failover to the second if the first becomes unreachable.


      The trunk registration information accepts IP address and DNS name, but not SRV record. Since these are dual SBCs, the SIP server, SIP outbound proxy, and SIP registrar are all the same. If I put in the SRV record registration simply fails.


      Failover documentation that I can find all references multiple registrars, not SBC environments.


      This is for NetVanta 6336 analog gateways in the field, and I've tried the latest 12.3.3 firmware.

        • Re: SRV records for SBC failover
          markfreeman Employee

          The SRV record is handled by DNS, you just have to put the FQDN as the sip server. The DNS server of the SBC should contain the SRV record.


          For example SIP trunk would look like this:

          voice trunk T01 type sip

            description "SOFTSWITCH TRUNK GROUP"

            sip-server primary sip-server.training.adtran


          The sip-server primary command can point to an IPv4 address or a hostname. Most providers have hostname pointing to a SRV record.


          Then you want to create a VoIP name service (VNS)

          voip name-service host sip-server.training.adtran sip udp

          voip name-service verification attempts 5 interval 30


          you can then see the SRV record using this command:

          1. show voip name-service cache

          Record Protocol Tpt       Port           Prior     Weight       Last Address

            • Re: SRV records for SBC failover
              curthowland New Member

              "Most providers have hostname pointing to a SRV record.


              I'm trying to figure out how to word this, forgive me if I seem to not get it.


              I have two DNS entries, SBC-East, SBC-West, each pointing to one IP address.


              The srv record, _srv_sbc-east, points to both with SBC-East listed first.


              When I put SBC-East in the 6336 as the Registrar, registration works. when I put _srv_sbc-east in, registration fails.


              Clearly the DNS lookup of _srv_sbc-east is not returning what is expected.


              In your example,


              voip name-service host SBC-East sip udp


              ...isn't going to do any good, because it only returns on IP address.


              So would,


              voip name-service host _srv_sbc-east sip udp


              ...be the correct form?