Does a cisco (CME) support DNS SRV ?

[mcroft]

Hi,

Hoope you can help.

Does Cisco CME (cisco 2800 running 12.4) support DNS SRV ?

If so, is this possible ?

Sip-ua

     registrar dns:_sip._udp.mydomain.com

     sip-server dns:_sip._udp.mydomain.com

Any help appreciated.

thanks

[paolo bevilacqua]

Yes, of course.

[mcroft]

Uhmmmm.

Can't find any supporting docs. and when I do a "show hosts".

it looks like it has fallen back to using the A record.

[paolo bevilacqua]

I have to admit I don't understand what the actual request is. Cisco IOS uses A records for any name to IP resolve.

[Roger Kallberg]

As Paulo wrote, the GW will use a A record for resolving the name. I don't think you can use a SRV record.

For Paulos reference I dug up this link, http://blog.lithiumblue.com/2007/07/understanding-dns-srv-records-and-sip.html?m=1

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[Jonathan Schulenberg]

A few minutes of searching has turned up several references to SRV support; however, none of them specifically show it being done with a registrar.

http://ben.thepolzins.us/2010/02/06/using-dns-srv-records-with-ios-dial-peers/

http://www.cisco.com/en/US/products/ps10592/prod_command_reference_list.html

Interesting to note that in the first example he is just providing the DNS zone, not the _udp._sip portion.

Assuming you have the time and an active support contract this may be worth a TAC case. It works on a dial-peer and uses the same dns: formatting. I fail to see why it shouldn't work, esspecially since there is no documentation saying it will on a dial-peer but not on the registrar command.

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[m-ketchum]

To the originial poster...

The DNS SRV record will be created on the DNS server, not the under the dial-peer or sip-ua.  If the router is also acting as the DNS server, in that case the SRV record will be created on the router, but under the DNS server configuration.

The arugument under the dial-peer or sip-ua will simply be:

session target dns:mydomain.com

The router will send the request to resolve mydomain.com to the DNS server containing the SRV record (either router or seperate server).  The DNS server will respond per the SRV record informing the router what IP and port to use for the SIP invite.