7941 Not failing over to 2nd SBC using DNS SRV Record..

Unanswered Question

Topology - 7941 phone configured to use SIP - connected to a Linksys Switch which is connected to a IAD 2400 Series Router. All Phones register to a DNS Name called VOIP.XXXXXX.NET - This DNS correlates to our 2 Session Border Controllers. Call them SBC 1 and SBC 2.

When SBC 1 is online the phone functions without any issues. Place calls, receive calls, everything works flawlessly.

When we take SBC 1 offline to test redundancy and failover. The 7941 loses its registration and when I do a capture I only see the registration go out to VOIP.XXXXXXXX.NET but it is querying the IP address of SBC1 for the registration it never queries SBC2's IP Address for the registration. I have added the IP Address of SBC 2 in the Backup Proxy, Emergency Proxy everywhere in the config but when I take SBC1 online it never queries the IP of SBC2. I am at a dead end. PLEASE HELP I'M LOSING MY MIND TRYING TO FIGURE OUT THIS ISSUE.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
paolo bevilacqua Wed, 01/23/2008 - 03:19
User Badges:
  • Super Gold, 25000 points or more
  • Hall of Fame,

    Founding Member


if you want your redundancy be based on DNS, you need to use a DNS server that changes address given in reply, based on the condition of fault. I would not be able to suggest a product or config that does that.

The phone is not supposed to try to registerto anything else after it got a valid reply from the DNS query.

paolo bevilacqua Wed, 01/23/2008 - 16:37
User Badges:
  • Super Gold, 25000 points or more
  • Hall of Fame,

    Founding Member

From what I understand, the phone can try to use the servers according to the tags under , according to .

It will not rely on the fact that there are multiple address in an DNS reply for a query to discover a server's address.


This Discussion