CUCM 11 Intra-Cluster Communication Signaling

[madhav.kumar.bhardwaj12]

We are deploying single CUCM 11 Cluster at APAC locations---1 PUB and 1 SUB at Australia , 1 SUB at New Zealand , 1 SUB at Hong Kong and 1 SUB at Singapore. Provided that distance between AUS and Hong Kong is around 7000 KM so will there be any issue with Intra-Cluster Communication Signaling over such a distance.?

[Suresh Hudda]

The maximum one-way delay between any Cisco CallManager servers for all priority ICCS traffic should not exceed 20 ms, or 40 ms round-trip time
(RTT). Delay for other ICCS traffic should be kept reasonable to provide timely database and directory access. Measuring the delay is covered in.

Propagation delay between two sites introduces 6 microseconds per kilometer without any other network delays being considered. This equates to a theoretical maximum distance of approximately 3000 km for 20 ms delay or approximately 1860 miles. These distances are provided only as relative
guidelines and in reality will be shorter due to other delay incurred within the network.

I would suggest to have separate cluster here, if distance is more than 3000 km, or if you can manage required latency then I believe distance doesn't matter.

Suresh

[pkinane]

It is actually 80 ms RTT. Even higher for a SME cluster.

http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab11/collab11/models.html

Delay

The maximum one-way delay between any two Unified CM servers should not exceed 40 ms, or 80 ms round-trip time. Measuring the delay is covered in Delay Testing. Propagation delay between two sites introduces 6 microseconds per kilometer without any other network delays being considered. This equates to a theoretical maximum distance of approximately 6,000 km for 40 ms delay or approximately 3,720 miles. These distances are provided only as relative guidelines and in reality will be shorter due to other delay incurred within the network.

What is the RTT when you ping a device in AUS using a device in HK?

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[Suresh Hudda]

In earlier releases it was 20-40 ms..but yes, for new cucm release srnd says it is 40-80 ms.

Suresh

[Chris Deren]

In addition to great answer from Suresh (+5) you can find the requirements in SRND.

One question though, why are you placing a sub at each location? This is not ideal deployment architecture as there is significant traffic replicated between all the CUCM servers, and having them split in several location is asking for trouble.  Typically you split the cluster between 2 data centers and let the remote locations rely on SRST when WAN is down.

[pkinane]

Agreed. Especially now that routers have a much higher capacity for number of phones they can support in SRST.