[Serusers] DNS SRV lookup issue

[Tan, Chiang Kang]

I have some issues with DNS mapping too. I want to have a sip user with
sip:user1 at testdomain.com. In my location table, I however stored
sip:user1 at machine1.testdomain.com as machine1.testdomain.com maps to the
actual IP address (I have such an entry in /etc/hosts). Hence although a DNS
SRV lookup is performed, it tries to contact
_sip._udp.machine1.testdomain.com, which does not exist (I only have SRV
entry for _sip._udp.testdomain.com). I think I'm missing something, can
somebody tell me where?

Any help will be greatly appreciated.

cheers
Chiang

-----Original Message-----
From: Zeus Ng [mailto:zeus.ng at isquare.com.au]
Sent: 24 February 2005 09:04
To: 'Gandhi, Chetan'
Cc: serusers at lists.iptel.org
Subject: RE: [Serusers] DNS SRV lookup issue


Are you absolutely sure the contact address is stored as user at testdomain.com
and not user at some.ip.address in the location table? I'm sure t_relay() will
do SRV lookup, with one condition. The URI should be in the form
sip:user at testdomain.com, with no port specified. If the URI does have the
port included like sip:user at testdomain.com:5060, then SER will not do SRV
lookup.

Most UAs I saw use IP address in contact header and that means no SRV
lookup. Better check yours with serctl ul show.

You can verify the SRV lookup with the following script.

loadmodule "/usr/local/lib/ser/modules/tm.so"

route{
        rewritehost("stupid.domain");
        t_relay();
}

The ethereal output will show SRV lookup.


Zeus

> -----Original Message-----
> From: serusers-bounces at lists.iptel.org 
> [mailto:serusers-bounces at lists.iptel.org] On Behalf Of Gandhi, Chetan
> Sent: Wednesday, 23 February 2005 9:15 AM
> To: serusers at lists.iptel.org
> Subject: [Serusers] DNS SRV lookup issue
> 
> 
> Hi All,
> 
>  
> 
> I am facing problem to get SER to do a SRV lookup. I have the 
> following scenario.
> 
>  
> 
> Step 1: 
> 
> SIP UA1 registers with SER (testdomain.com) with contact 
> address user at testdomain.com
> 
> SIP UA2 registers with SER (testdomain.com) with contact 
> address user at testdomain.com
> 
>  
> 
> Step 2: 
> 
> SIP UA3 calls user at testdomain.com
> 
>  
> 
> Problem
> 
> I would expect SER to do a DNS SRV lookup on testdomain.com 
> and get sip1.testdomain.com and sip2.testdomain.com. 
> Unfortunately, SER only does A and AAAA query. (verified via 
> ethereal) and does not do SRV lookup. How can I make it do 
> SRV lookup ? I am using the default ser.cfg file.
> 
>  
> 
>  
> 
> DNS entries
> 
> _sip._udp.testdomain.com.                     3600     IN     
>     SRV     0          1          5060     sip1.testdomain.com.
> 
> _sip._udp.testdomain.com.                     3600     IN     
>     SRV     0          1          5060     sip2.testdomain.com.
> 
>  
> 
> I am trying to do load balancing but the SRV lookup failure 
> has got me stuck. Any pointers would be really appreciated.
> 
>  
> 
> Thanks,
> 
> Chetan
> 
> 

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