DNS SRV Record Issue + VCS Expressway

Answered Question
Apr 29th, 2012

HI All,

I have a VCS Expressway running in DMZ, and i am facing some issue with DNS SRV Records.

VCS Expressway Hostname:- VCSe

Domain: example.com

VCSE FQDN: VCSe.example.com

and i have a A Record configured for the same FQDN in Public DNS Server.

I have a sip domain configured as "cisco.com" in my VCS Expressway.

So what is the SRV Records i need to create in Public DNS Server.

Regards,

Nikhil Jayan

I have this problem too.
0 votes
Correct Answer by aljaiswa about 1 year 11 months ago

Nikhil,

It seems you haven't checked the link i sent you earlier.. Those documents a very self explanatory. Anyways the one we talked earlier is we were talking for signaling to send the calls to expressway as well as registration part.

In your deployment you have different domain for DNS and SIP domain. Also as you said you are having cluster of expressway and you want registration for endpoints as well then again i would suggest you to check the document for cluster creation on cisco webesite.

Now if you  have a cluster for expressway then you need to create multiple srv records which would be pointing to each FQDN of cluster peer with equal weight. In a normal scneario use of common domain for different services are recommended.

The srv records would be seen someting like this.

_sips._tcp.company.com. 86400 IN SRV 1 1 5061 vcse1.company.com.

_sips._tcp.company.com. 86400 IN SRV 1 1 5061 vcse2.company.com.

_sip._tcp.company.com. 86400 IN SRV 1 1 5060 vcse1.company.com.

_sip._tcp.company.com. 86400 IN SRV 1 1 5060 vcse2.company.com.

_h323ls._udp.company.com. 86400 IN SRV 1 1 1719 vcse1.company.com.

_h323ls._udp.company.com. 86400 IN SRV 1 1 1719 vcse2.company.com.

_h323cs._tcp.company.com. 86400 IN SRV 1 1 1720 vcse1.company.com.

_h323cs._tcp.company.com. 86400 IN SRV 1 1 1720 vcse2.company.com.

_h323rs._udp.company.com. 86400 IN SRV 1 1 1719 vcse1.company.com.

_h323rs._udp.company.com. 86400 IN SRV 1 1 1719 vcse2.company.com.

However your case is different. In your deplyoment what you have to do is any request for the domain "cisco.com" should be resolved to FQDN of the VCS-Expressway peers with equal weight.

for e.g.

_tcp.gmail.com. IN SRV 20 0 5222     talk2.l.google.com.

so any request to gmail.com would resolve to talk2.1.google.com server.

same way you have to make it work.

Thanks

Alok

  • 1
  • 2
  • 3
  • 4
  • 5
Average Rating: 5 (2 ratings)
aljaiswa Sun, 04/29/2012 - 05:59

Hi Nikhil,

Basically we need srv records for SIP domain. So in case if some tries to reach your endpoints from an un-register endpoints they would be dialing for e.g. 1234@cisco.com or abc@cisco.com.

In this case the DNS srv records would be used to send the call to your expressway. The DNS srv records created for your SIP domain should resolve to public ip of expressway.

check the below link for more information.

http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/config_guide/Cisco_VCS_Basic_Configuration_Cisco_VCS_Control_with_Cisco_VCS_Expressway_Deployment_Guide_X7-1.pdf

check Appendix 2.

However in the e.g. given in document it has same domain like vcs expressway FQDN as "vcse.example.com" and sip domain is also "example.com".

but in your case you have both different. Just out of curiosity why you want to use different domains?

Anyways if you are only looking for dns srv records only for calling purpose then you should have srv records created for "cisco.com" and not "example.com" in your case.

However apart from calling the DNS srv records would be used for registration as well. I am not sure whether you are using registration from outside based on DNS srv records? if yes, then go thorugh the document below.

http://www.cisco.com/en/US/docs/telepresence/infrastructure/vcs/config_guide/Cisco_VCS_Cluster_Creation_and_Maintenance_Deployment_Guide_X7-1.pdf

Appendix 5 and 9

Thanks

Alok

darren.lapierre Sun, 04/29/2012 - 06:27

Alok is absolutely correct.

What i typically do is send off a condensed xls of the information that needs to be inputted to any external DNS management.

First, you will need to assign an A-name to your vcse (vcse.exampledomain.com, as an example). Then point your SRV records to that A record so. as you can see in the chart below, all the records are point to that A record that was created.

ServiceProtocolNamePriorityWeightPortTargetTTL
h323cs tcp _h323cs._tcp.exampledomain.com 10101720vcse.exampledomain.com86400
h323ls udp _h323ls._udp.exampledomain.com 10101719vcse.exampledomain.com86400
sip tcp _sip._tcp.exampledomain.com 10105060vcse.exampledomain.com86400
sip udp _sip._udp.exampledomain.com 10105060vcse.exampledomain.com86400
sips tcp _sips._tcp.exampledomain.com 10105061vcse.exampledomain.com86400
sips tls _sips._tls.exampledomain.com 10105061vcse.exampledomain.com86400
sip tls _sip._tls.exampledomain.com 10105061vcse.exampledomain.com86400

Once this is applied, anyone can call into my environment (eg, 1234@exampledomain.com).

Hopes this helps.

D.

nikhil.jayan@ma... Sun, 04/29/2012 - 07:28

Thanks Alok/Darren,

I have some more clarification related to the same SRV Records.

When the SRV Records are getting used, is this using for "call signaling" like the call from Video Endpoint which registered under different Domain or "Registering a Video Endpoint to VCS" (including CiscoJabber)?

When we will use the A Records, is it use for the Video Endpoint Registration purpose?

If i am doing a VCS Clustering and i have created a SRV Records for SIP Domain. In this SRV Record what is the Target A Record i need to give?, can i give the Cluster FQDN as a Target A Record. In that case do i need to have a A record created for VCS-Cluster FQDN or SRV Records which i created for clustering will work for this also?

Regards,

Nikhil Jayan.

Correct Answer
aljaiswa Sun, 04/29/2012 - 09:47

Nikhil,

It seems you haven't checked the link i sent you earlier.. Those documents a very self explanatory. Anyways the one we talked earlier is we were talking for signaling to send the calls to expressway as well as registration part.

In your deployment you have different domain for DNS and SIP domain. Also as you said you are having cluster of expressway and you want registration for endpoints as well then again i would suggest you to check the document for cluster creation on cisco webesite.

Now if you  have a cluster for expressway then you need to create multiple srv records which would be pointing to each FQDN of cluster peer with equal weight. In a normal scneario use of common domain for different services are recommended.

The srv records would be seen someting like this.

_sips._tcp.company.com. 86400 IN SRV 1 1 5061 vcse1.company.com.

_sips._tcp.company.com. 86400 IN SRV 1 1 5061 vcse2.company.com.

_sip._tcp.company.com. 86400 IN SRV 1 1 5060 vcse1.company.com.

_sip._tcp.company.com. 86400 IN SRV 1 1 5060 vcse2.company.com.

_h323ls._udp.company.com. 86400 IN SRV 1 1 1719 vcse1.company.com.

_h323ls._udp.company.com. 86400 IN SRV 1 1 1719 vcse2.company.com.

_h323cs._tcp.company.com. 86400 IN SRV 1 1 1720 vcse1.company.com.

_h323cs._tcp.company.com. 86400 IN SRV 1 1 1720 vcse2.company.com.

_h323rs._udp.company.com. 86400 IN SRV 1 1 1719 vcse1.company.com.

_h323rs._udp.company.com. 86400 IN SRV 1 1 1719 vcse2.company.com.

However your case is different. In your deplyoment what you have to do is any request for the domain "cisco.com" should be resolved to FQDN of the VCS-Expressway peers with equal weight.

for e.g.

_tcp.gmail.com. IN SRV 20 0 5222     talk2.l.google.com.

so any request to gmail.com would resolve to talk2.1.google.com server.

same way you have to make it work.

Thanks

Alok

sudhekum Sun, 04/29/2012 - 22:36

Hi Nikhil,

The SRV records is used for both registration purpose and also for calls from non-registered endpoints to be routed to the VCSe.

Thanks

Sudheer

awinter2 Sun, 04/29/2012 - 15:16

To comment on Darren's post, the _sip._tls and _sips._tls records are not in use by our endpoints (They were previously used by Movi and E20, which are now only using the standards-based records).

In fact, _sip._tls is an SRV record used by Microsoft, which normally points to OCS/Lync Edge servers, and should therefore not be pointing to a VCS-E.

- Andreas

Actions

Login or Register to take actions

This Discussion

Posted April 29, 2012 at 3:23 AM
Stats:
Replies:6 Avg. Rating:5
Views:3528 Votes:0
Shares:0
Tags: No tags.

Discussions Leaderboard