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

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.

3 REPLIES
Hall of Fame Super Gold

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

Hi,

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.

New Member

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

But if a phone is registered with the PRIMARY SBC; and the PRIMARY goes down and you send an INVITE and it doesn't reply back from the PRIMARY shouldn't the phone send that INVITE to the SECONDARY SBC automatically.

Hall of Fame Super Gold

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

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.

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