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Beginner

CMS CMA Failover - DNS

Hello ,

 

We've 3 CMS in our deployment and one DNS record for CMA . DNS record is pointing three ip adresses of our CMS. In case of failover (CMS1 down) , DNS still solve first CMS (CMS1) and it's failing. If we type "ipconfig /flushdns" to clear dns records on client computer , DNS start to solve second CMS(CMS2). Is there any way to solve other DNS records (CMS2 ,CMS3) without typing "ipconfig /flushdns" on client computer ? 

 

BR ,

Ibrahim

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1 REPLY 1
Beginner

Re: CMS CMA Failover - DNS

Don't do so :)

https://www.cisco.com/c/dam/en/us/td/docs/conferencing/ciscoMeetingServer/Deployment_Guide/Version-2-6/Cisco-Meeting-Server-2-6-Scalable-and-Resilient-Deployment.pdf

8.1 Deploying multiple Web Bridges

To find a Web Bridge, the browser performs a DNS A record lookup on the Web Bridge URI
specified, for example join.example.com. In deployments with multiple Web Bridges, the result
of this could be multiple IP addresses.
Unless a policy is in place, the browser can pick any of the DNS A records and switch between
them during a session . This may result in the Web RTC clients rehoming across Web Bridges
and causing connections to drop. The consequence of this will be that the user has a very poor
user experience during the conference, with the call repeatedly dropping.

 

I recommend you to use load balancer. DNS A should points to a single balancer's IP address. Don't forget to increase sticky timer for user's sessions.

 

We are using Brocade ADX:

nslookup meetings.domain
Address: 10.1.1.10

server virtual cms-VIP 10.1.1.10
description CiscoMeetingServers
sticky-age 60
sticky-age-multiplier 8
sym-priority 59
next-hop 10.1.1.1
port default disable
port ssl sticky
bind ssl cms-real1 ssl cms-real2 ssl

server remote-name cms-real1 10.2.2.11
source-nat
port ssl
port ssl keepalive
port ssl l4-check-only
port ssl l4-bringup-interval 10
server remote-name cms-real2 10.2.2.12
source-nat
port ssl
port ssl keepalive
port ssl l4-check-only
port ssl l4-bringup-interval 10

 

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