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latency between CallManager Publisher and Subscriber

I'm in a small debate on whether you can split a cluster over a WAN connection. I have a cluster at Site A. I want to add another Sub at Site B because the site is going to have 250 IP phones. I can utilize this site with the Subscriber at Site B as my failover site for Site A.

I'm getting push back on this design. If the latency is too large (over 40ms)between the sub at site b and Pub at Site A, this could cause some issues. Does Cisco have any best practices for this if you want to split a cluster over a WAN link?



Re: latency between CallManager Publisher and Subscriber

subscribers across a WAN are fairly common i've seen.

40ms is not to bad for RTP streams especially if good QoS in place. (priority intracluster communication signalling states maximum 40ms RTT; all other ICCS traffic can be 'reasonable')

the jitter, if any, will be something you'll want to watch for in higher latency cases. this will cause undesirable voice even if latency overall is not too high.

how many BCHA do you expect across the WAN?

how much bandwidth across the WAN do you have?

are you going to create separate gateways for remote-site, off prim calls? (recommended)

see the following link for 'Clustering Over an WAN':