Loadbalance CMS webrtc sessions over multiple expressways

[Steven Johnston]

From the perspective of an external user on the internet who is provided with a web link to join a CMS space as a webrtc guest. On clicking the link they are resolving a DNS A record that resolves to several expressway servers (cluster)

Generally speaking the A record lookup is sending these users to the same expressway server.

Can anybody recommend a way to load balance webrtc across multiple expressway servers, it is not a scenario that is mentioned in the design guides. Would i need to deploy a load balancer or can i do something with SRV records?

thanks

[abcdedghi1]

I would surely use the DNS records to round robin the requests between expressways.

So let's say your public domain to reach the expressways is join.company.com.

i would create a entry on the public domain with the name join and pointing to each of the public exp-e's so that it round robins between the expressways.

that way you don't really need the "loadbalancer" as you are leveraging DNS to reach the expressways in your DMZ.

[Ayodeji Okanlawon]

While this may work, it is definitely not an ideal or optimized solution. DNS can't provide a stateful failover for servers. When a server is offline, there is no way for DNS to detect this and users run the risk of been redirected to that server. A load balancer us definitely a preferred solution

[abcdedghi1]

What version of cms do you have?  And whAt kind of deployment?  

[Steven Johnston]

Version 2.9

Combined server deployment with 3 node cluster 

[manipandey]

I doubt it will work. DNS based is one way.

Public facing Expressway like it does load balancing some sort for call and endpoint registration should be able to loadbalance but currently it's not working for Webrtc.  Infact if in a cluster one limit a CMS for certain number of calls, currently it cannot rollover to the 2nd CMS in cluster...

Somehow Expressway and CMS team need to collaborate timely to make it happen as this is not a major ask to say but some flaw in call treatment of Webrtc. 

Looking forward to hear from someone who has really achieve the loadbalance AND OR BC/DR for a CMS cluster...

Thanks 

M

[abcdedghi1]

a few things Cisco is currently working on making more efficient this things like are one of them.

however i believe the question was a true load balance between the peer in exp-e cluster from the internet.

and you have mentioned calls going to the second CMS peer? you referred to a limit.

can you explain a tad so I understand clearly.

I say that because I just finished deploying a 5 peer cluster of CMS with a 2 peer cluster of exp-e. and I know what I did to get it all going. Ran into some undocumented  bugs in the way CMS works. So maybe if i understand I can add some more value. 

[Steven Johnston]

Did you deploy webrtc via expressway proxy, and if so how did you go about load balancing the guest sessions over the exp-e nodes. 

[Ayodeji Okanlawon]

For the purpose of this discussion and the over all spirit of this community, I think it would be nice if you detail how you achieved load balancing and the issues you faced. Your deployment looks like something we can all learn from.

Thanks