Hi,

I am exploring different redundancy / load-balancing models for a Kamailio cluster.

When I say cluster, I mean, a number (N) of Kamailio nodes acting as stateful proxies.

Each node is configured the same as the others, and all have access to the same lookup data to make routing decisions.

I would appreciate any advice or experience any of you can share on these different models.

Overall model:

1. Direct to proxies
2. Redirect servers first, which redirect to proxies

Selecting the first node to talk to. Each model could use either type of selection.

1. DNS-based (SRV or NAPTR, client makes call to dns name)
2. Anycast with ECMP (equal-cost multi-path routing)
3. Cluster with a mobile IP and service-down detection (this would just provide 1:1 protection)

Have clients make calls through the proxy using a DNS record containing an SRV record for each node (or, alternatively, done with NAPTR). Would rely on the client to switch nodes in the event of a node failure mid-call. (Is that even possible?)

Anycast would only work with UDP signaling. Use Anycast to find the first proxy, then use stateful responses to direct client back to same node for subsequent messages in a dialog.

So for anyone who has tried any of these methods, I would love to hear the pros and cons..

Thanks in advance!

Jawaid