Registering VG224 - pros and cons of Pub vs Sub?

[jeffrey.girard]

In the sccp ccm configuration of the VG 224. 

What are you opinions?  Pub or Sub as first priority?  Assume a cluster with multiple subs.

Pros and Cons of each?

Jeff

[Chris Deren]

With multiple Subs I would not even recommend running CM service on the Pub. Always prefer Sub over Pub for all processing and registration.

HTH,

Chris

[jeffrey.girard]

What is the reasoning? 

I understand that most everyone considers it to be "Best Business Practice"

Im looking for any real reasons.

Other than heatbeat / keepalives - what additional stress/load is a VG224 putting on the CUCM?  The individual ports will register to the appropriate CUCM based upon the device pool and teh resources consumed by the attached device will be based upon the MRGL.

So, Im looking for some hard and fast facts on what additional stressors are placed upon the CUCM from the VG?

Jeff

[Chris Deren]

Jeff,

The main reason is that Publisher is responsible for master database which may be intensive in large cluster so any additional impactful services should be avoided. CM service can require quite some processing power for controlling devices, call processing, ICCS traffic, etc.  So, if you have sufficient number of subs the recommendation is to use those for all call processing.  So, the minute you enable CM service it is not just responsible for the device that registers to it, but participates in the ICCS traffic exchange which depending on cluster size can be CPU imactful and bandwidth impactful.

This is described in CUCM SRND documentation.

HTH,

Chris