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New Member

local Subscribers vs. remote Subscribers for Large Sites

Hi Team,

in a centralized CUCM Cluster significant bandwidth is needed for connection of large sites (> 2000 users) to the central applications.

I try to find out, if its better in type of WAN bandwidth and stability

1) to design a Cluster over WAN with local Subscribers and reduce the traffic between phones and Call-Processors but having the Cluster over WAN requirements on the WAN

2) centralize all subscribers

The SRND bandwidth calculations do not

finally judge me.

My feeling says that the Cluster-over-WAN is more batch-traffic and can revover after a WAN failure without large user impact where as the Phone-to-Subscriber traffic is more

real-time and a problem on the WAN

may lead to SRST toggeling, so local Subscribers might be more reliable.

Any comment or better experience is highly welcome...

best regards,


Hall of Fame Super Red

Re: local Subscribers vs. remote Subscribers for Large Sites

Hi Alfred,

For large sites, like you nicely noted, I would use "local" Subscribers as a Best Practice :)

These guides should be followed when planning;

Multisite with Distributed Call Processing

And this is really your best bet!

Local Failover Deployment Model

Hope this helps!


New Member

Re: local Subscribers vs. remote Subscribers for Large Sites

Hi Rob,

thx for your comment.

To be a little more precise from my side. As long as this would be possible I would like to stay on one Cluster or Supercluster. Having 6 of these large sites with a local subscriber and remote failover the Cluster over WAN would consume 7 Mbps from Publisher to each site, means > 42 Mbps, assuming the Calculation from the the SRND Example 2-1.

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