Solved: CUCM 10.5.2- Reboot Svrs - 2 Subs - phone behavior questions

lleweyiss · ‎08-10-2017

I have 1 Pub & 2 Subs ... for a maintenance patching of the ESX servers I need to gracefully shut down the Pub then Sub #1.

Sub #2 will remain up until Pub & Sub #1 are back up.

1) When the Sub #1 goes down, Will the phones re-register / restart / or reset to become registered to Sub #2 - looking to determine impact & estimated time to communicate to users - (24x7 call center -offices world wide> US, Japan, India, Brazil, etc )

Both Sub's are listed in a Cisco Unified CM Group together and it's the only one used by all phone device pools (if that make any difference in this scenario).

2) once Sub #1 is back up , (its listed 1st in the CM Group) , will the phone automatically go back to Sub #1 or it will it only occur once I gracefully shutdown Sub #2 ?

Jitender Bhandari · ‎08-11-2017

Hi

1) When the Sub #1 goes down, Will the phones re-register / restart / or reset to become registered to Sub #2 - looking to determine impact & estimated time to communicate to users - (24x7 call center -offices world wide> US, Japan, India, Brazil, etc )

Ans) Yes they would not go through the complete boot cycle, if you are looking at the phone would would just see a blip and the phone would register to SUB in less than 2 seconds (Keeping in mind there is enough bandwidth for all the phones to failover to secondary server.). The reason for fast failover is the phone keeps an active OSI layer 4 TCP connection with secondary CUCM server in the list of server in CCM group. So there is only layer 7 connection needs to be established either SCCP or SIP.

2) once Sub #1 is back up , (its listed 1st in the CM Group) , will the phone automatically go back to Sub #1 or it will it only occur once I gracefully shutdown Sub #2 ?

Ans) Yes the phone would failback to primary server as it is back and providing registration. If it is on active call, then the call would stay up and the moment you handup on phone again you would see just a blip on the phone and it will come back to Primary CUCM in your case SUB 1

(Rate if it helps)

JB

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Jaime Valencia · ‎08-10-2017

Yes, because you have both servers in the CUCM group used by phones.

CUCM groups are ordered, if a server with higher preference is available, they will register to it, until they register to the one on top of the list.

HTH

java

if this helps, please rate

lleweyiss · ‎08-11-2017

Hi Jamie,

So that I understand your response to my questions :

#1) - you are saying: "yes" all phones will go through a re-register to get to Sub #2?

If so, will it be a full Reset, or the shorter time frame of Restart to find Sub #2 ?

#2) you are saying: once Sub #1 is back up, the phones will see that automatically and register to it, it wont be my action of powering down the Sub #2 ?

Thanks !

Jitender Bhandari · ‎08-11-2017

Hi

1) When the Sub #1 goes down, Will the phones re-register / restart / or reset to become registered to Sub #2 - looking to determine impact & estimated time to communicate to users - (24x7 call center -offices world wide> US, Japan, India, Brazil, etc )

Ans) Yes they would not go through the complete boot cycle, if you are looking at the phone would would just see a blip and the phone would register to SUB in less than 2 seconds (Keeping in mind there is enough bandwidth for all the phones to failover to secondary server.). The reason for fast failover is the phone keeps an active OSI layer 4 TCP connection with secondary CUCM server in the list of server in CCM group. So there is only layer 7 connection needs to be established either SCCP or SIP.

2) once Sub #1 is back up , (its listed 1st in the CM Group) , will the phone automatically go back to Sub #1 or it will it only occur once I gracefully shutdown Sub #2 ?

Ans) Yes the phone would failback to primary server as it is back and providing registration. If it is on active call, then the call would stay up and the moment you handup on phone again you would see just a blip on the phone and it will come back to Primary CUCM in your case SUB 1

(Rate if it helps)

JB

lleweyiss · ‎08-11-2017

Hi Jitender,

Thanks so much for the extended reply ! that is what I was really hoping to get, so now I can set the expectation on impact to the call center .

Jitender Bhandari · ‎08-11-2017

Hi

The reason i mentioned those point are because you mentioned it is a call center environment. Also if you know it would work and dont know why and how it difficult to explain to other. Some more information on failover might help in future worth reading.

https://supportforums.cisco.com/document/74666/cucm-ip-phone-sccp-keepalive-and-failover-architecture

(Rate if it helps)

JB

lleweyiss · ‎08-11-2017

Greatly appreciated, very helpful indeed !!