FW: [Users] SIP clients and DNS SRV

[Helge Waastad]

 Forgot CC on this one.....

-----Original Message-----
From: Helge Waastad 
Sent: 26. oktober 2005 13:56
To: 'Zen Kato'
Subject: RE: [Users] SIP clients and DNS SRV

Hi,
You know, even if DNS SRV works fine, you will have problems with NAT'ed
clients behind firewalls.
Ther reason is that the session is opened between the server handeling
the registration and the UAC.
If this on crashes, the second one will never be able to send INVITE to
the UAC since there is no open session through the firewall.

Yes, you will see service unavaliability up to the registration
interval, depending on the UAC functionality.

The only solution for this is a (outbound) proxy cluster using Linux-HA
(or vrrp) and a IP address take-over.
(Or a Border Controller, but these are not for free..)

Cisco 7960 works fine (also snom)
I've seen that Sipura in 3.1.5 release also supports dns srv for
redundancy/failover, but I have'nt tried it.



-----Original Message-----
From: Zen Kato [mailto:zenkato at pis.bekkoame.ne.jp]
Sent: 26. oktober 2005 13:45
To: Helge Waastad
Cc: klaus.mailinglists at pernau.at; users at openser.org
Subject: Re: [Users] SIP clients and DNS SRV

Hi,

I posted on [serusers] regarding DNS SRV,t_replicate,backup server and
GS phones.
My test resut of BT101(1.0.7.11-newest) and GXP2000(1.0.1.9) was no
good.

My question is eventhough we set up DNS SRV on server side, if sip
clients does not suppot DNS SRV, do we have a risk of (5+5)minutes out
of service time when we set up 5 minutes REGISTER intervals?

If UA have multiple REGISTERs outgoing lines such as GXP2000, we could
set up Line1 for sip1&sip2(DNS SRV) Line2 for sip3 server.
In this case if line1 does not work, the user can use Line2.

Xlite can register 3 sip servers, but only default sip proxy can use as
outgoing line, so the Xlite users have (5+5)minutes out of service risk.

Does Cisco 7960 work perfectly on DNS SRV?

Regards,

Zen 

Helge Waastad wrote  :

> Hi,
> I've started to add some more information to voip-info.
> I'm still waiting for response from Grandstream and others on their 
> support (or future support) for DNS SRV.
> 
> br hw
> 
> On Wed, 2005-10-19 at 17:32 +0200, Klaus Darilion wrote:
> > Hi Helge!
> > 
> > According to my tests, also SNOM can do SRV based failover.
> > 
> > I've published my test results at:
> > http://www.voip-info.org/wiki/view/SRV+implementations
> > 
> > Please add your test results to this.
> > 
> > regards
> > klaus
> > 
> > Helge Waastad wrote:
> > > Hi,
> > > this is not a technical question regarding OpenSER, but more of 
> > > req for information.
> > > 
> > > I'm using Cisco phones and gateways and have implemented DNS SRV 
> > > redundancy.
> > > However, I have never seen a SIP phone that really works with DNS 
> > > SRV redundancy, except from Cisco. (which actually works as a
> > > charm)
> > > 
> > > Does anyone know other phones that can use dns srv for redundancy?
> > > 
> > > At least Cisco tries the next DNS SRV entry if it receives a port 
> > > unreachable from the highest priority proxy...
> > > 
> > > 
> > 
> --
> mvh/best regards
> Helge Waastad
> System Engineer
> Smartnet
> (+47)67830017
> 
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