asterisk users - Jul 2005 - SIP phone failover using DNS SRV?

Has anyone successfully had a SIP phone fail over from Asterisk Server A to
Server B using DNS SRV?

If so, which phone worked for you? I'm assuming you set up your DNS SRV
records so that the IP addresses of A and B are associated with the same name,
and both servers have equal priority and equal weight.

In order to make calls through B after A goes down, do you have to wait as long
as the registration retry interval? Or can you make calls through B as soon as
you pick up the phone and dial, because the INVITE message through A fails, and
the phone re-sends the INVITE through B?

Thanks for any help. We've been trying this with Aastra 480i phones and SJ
Phone without much luck so far.

Rana

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Rana Dutt wrote:
> Has anyone successfully had a SIP phone fail over from Asterisk Server A to
Server B using DNS SRV?
> 
> If so, which phone worked for you? I'm assuming you set up your DNS SRV
records so that the IP
 >adresses of A and B are associated with the same name, and both 
servers have equal priority and equal weight.
> 
> In order to make calls through B after A goes down, do you have to wait as
long as the registration retry
 > interval? Or can you make calls through B as soon as you pick up the 
phone and dial, because the INVITE
 >message through A fails, and the phone re-sends the INVITE through
B?
> 
> Thanks for any help. We've been trying this with Aastra 480i phones and
SJ Phone without much luck so far.
I do this with SIPura.  I tell the box to use DNS SRV records.  The 
first record points to the internal IP of my asterisk server (for use 
when I am at the home/office).  The second one points to the external IP 
of my router that has port forwarding.  I can roam pretty much anywhere 
without any reconfiguration.

-- 
Eric Wieling * BTEL Consulting * 504-210-3699 x2120

>	Has anyone successfully had a SIP phone fail over from Asterisk
Server A to Server B using DNS SRV? 

Definitely we have been doing this for quite a while.
	 
>	If so, which phone worked for you? I'm assuming you set up your
DNS SRV records so that the IP 
> addresses of A and B are associated with the same name, and both
servers have equal priority and equal 
>weight. 
We have this working great with both Polycom and Sipura devices. We have
servers of different priority (i.e. - primary then failover). The name
is the same. 
	 
>	In order to make calls through B after A goes down, do you have
to wait as long as the registration
> retry interval? Or can you make calls through B as soon as you pick up
the phone and dial, because the
> INVITE message through A fails, and the phone re-sends the INVITE
through B?  

The way we have it working A is a higher priority than B, so every phone
will register to A unless it is down (or the phone is having
connectivity issues and points itself to B automatically). In this case
when A goes down each phone will automatically failover to B when the
next call is placed. There is still an issue of inbound calls, but most
carriers will provide a mechanism to fail calls over as well (if the
server is truly down).

The regisration retry interval (to the best of my knowledge) is how long
the phone will wait before attempting to re-register with servers of a
higher priority after failing over. We tend to set this as a pretty low
number because we want things to get back to the primary as soon as
possible (since our carriers will fail back immediately for any new call
coming in once the server is back up).

-Steve