[Serusers] ser 0.9.7-pre3 SRV "question"

Steve Blair blairs at isc.upenn.edu
Tue Jul 25 20:26:37 CEST 2006


We are running ser 0.9.7-pre3 and seeing some strange behavior. I'm 
hoping someone on this list might have some input.

 Our SIP domain name is actually an SRV service name that points to two 
A records. This configuration has existed for years and has worked reliably.

      _sip._udp.myserver.myschool.edu     service = 1 5 5060 
      _sip._udp.myserver.myschool.edu     service = 3 5 5060 

  The "myserver.myschool.edu" name is not the real name it is just for 
discussion purposes. The name "myserver.myschool.edu"  has other SRV 
records associated with it. For example:

 > set type=SRV

    _kerberos._udp.net.isc.upenn.edu        service = 0 100 88 
    _kerberos._udp.net.isc.upenn.edu        service = 0 100 88 

 In the past month we upgraded to this release of SER and noticed a 
problem when users call forward their extension to an off campus PSTN 

 If the Call Forward Always flag is set to Y then the R-URI is 
re-written to be a new user portion with our SIP domain name appended as 
the hostname. In some ngrep traces I'm seeing our proxy trying to send 
the forwarded call to a next hop address of "pops.myserver.myschool.edu" 
as shown above. The problem is pops is not a SIP server.

 The only connection between our SIP environment and the host pops is 
the domain name.  This suggests an issue with SRV resolution but I do 
not see the problem in my traces. Does anyone have any thoughts on this 


ISC Network Engineering
The University of Pennsylvania
3401 Walnut Street, Suite 221A
Philadelphia, PA 19104  

voice: 215-573-8396 


fax: 215-898-9348    

sip:blairs at net.isc.upenn.edu

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