I've seen many examples of the DNS SRV records and have read the VCS Cluster Creation Deployment Guide for X8.1 example. I was hoping I could a second set of eyes to verify that my DNS configuration below is accurate. Here is what I have so far:
VCS Expressway LAN 1 Ports are to be used for the VCS Cluster in the DMZ and will not be NAT'd. LAN 2 Ports point to the public internet and are NAT'd.
- Domain: vc.example.com
- Cluster A Record: vcse-nb.vc.example.com points to both VCS Expressway IP address in Round Robin fashion with equal weight and priority (12.x.x.1 and 12.x.x.2)
- VCS Expressway A Records
Vcse-nb-1.vc.example.com – 12.x.x.1
Vcse-nb-2.vc.example.com – 12.x.x.2
DNS SRV Records
_sips._tcp.vc.example.com. 86400 IN SRV 1 1 5061 vcse-nb-1.vc.example.com.
_sips._tcp.vc.example.com. 86400 IN SRV 1 1 5061 vcse-nb-2.vc.example.com.
_sip._tcp.vc.example.com. 86400 IN SRV 1 1 5060 vcse-nb-1.vc.example.com.
_sip._tcp.vc.example.com. 86400 IN SRV 1 1 5060 vcse-nb-2.vc.example.com.
_h323ls._udp.vc.example.com. 86400 IN SRV 1 1 1719 vcse-nb-1.vc.example.com.
_h323ls._udp.vc.example.com. 86400 IN SRV 1 1 1719 vcse-nb-2.vc.example.com.
_h323cs._tcp.vc.example.com. 86400 IN SRV 1 1 1720 vcse-nb-1.vc.example.com.
_h323cs._tcp.vc.example.com. 86400 IN SRV 1 1 1720 vcse-nb-2.vc.example.com.
My question is in this example would I need to create SRV records that point to the Cluster A record? I have seen many examples of this but I can't seem to wrap my head around why this would be needed. I appreciate you help!
There are a few ways you can approach this.
I've seen some sites that use either methods above, and they both work.
Going off of your examples in your post, you are correct.
Thank you Patrick! So in my scenario would the Cluster A record just be used for endpoint registration and redundancy while the DNS SRV records would be used for locating the VCS Expressways based upon the service protocol for call processing?
I've never really understood the part about the cluster FQDN portion of the deployment guide, I believe it was used with the old provisioning model within TMS, (TMS Agent Legacy), but I can't say for certain.
DNS SRV records could be for both registration and calling. Note, if you'd like to use SRV records to register H323 endpoints, you'd also need to include _h323rs._tcp over port 1719.
We use a single SRV record for each protocol/port pointing to a cluster FQDN, which has each peers A record assigned to it. If anything, you could configure all parts of it if you're unsure. I know I ran through this same scenario as you when we implemented a VCS Expressway this past December, trying to wrap our heads around the DNS portion, what is what, and how to best approach it.
Hi Patrik, I have many doubts or round robin dns srv , but your explanation is very good.
as in the previous example :
We use a single SRV record for each protocol/port pointing to a cluster FQDN, which has each peers A record assigned
How to do that in DNS?
name = 1 ip?
Sorry , I do not know dns
SRV record would point to your VCS Expressway cluster FQDN. Your VCS-E cluster FQDN would point to each Expressway peer. You create an A record with the same domain entry for each peer IP address.
A record for each vcse :
vcse1.vc.domain.com point IP public vcse1
vcsex.vc.domain.com point IP public vcsex
FQDN for cluster name :
vc.domain.com point to vcse1.vc.domain.com and vcsex.vc.domain.com?
oh , sorry , my knowledge are very limits !!!
vc.domain.com points to both vcse1 and vcsex IP address. In DNS, you can create an A record using the same domain (vc.domain.com) pointing to several IPs. And anything trying to communicate to that domain will use round-robin, making their way through each IP.