Standby CUCM and Phone Registration

[justserve]

Hi,

I have a CUCM cluster with 3 servers - 1 Publisher (PUB) and 2 Subscribers (SUB1 and SUB2).

SCENARIO:

CUCM Configuration (in the order of priority): SUB1, SUB2, PUB

The phones are registered to SUB1 as the Active (Unified CM 1) but none of the other two servers SUB1 and PUB act as standby though the hostnames are displayed (displayed IP address is 0.0.0.0) in the Unified Configuration setting on the phones as Standby.

When SUB1 lost connectivity or shutdown, phones do not register to SUB2 or PUB. On the phones the hostnames for SUB2 and PUB are seen but the IP address displayed is 0.0.0.0 instead of the actual IP address .

All hostnames and IP addresses are correct and exist on the DNS Server.

What could be the cause? How can I resolve this?

Thank you.

[yahsiel2004]

Does the phones have the correct DNS servers?

Yosh

[yahsiel2004]

Can you ping SUB2 and PUB from the phones vlan? What version of CUCM are you runing?

Yosh

[Chris Deren]

So, you verified the phone is using device pool which uses CM Group that lists all 3 servers?

Is it SCCP or SIP phone, what version of CUCM are you using?

Chris

[justserve]

I have checked again and all the three servers are in the CM Group.

The phones are SCCP and the CUCM version is 7.1.5 (7.1.5.32900-2).

In addition, in the Unified CM Configuration on the phone, if I select Unified CM 2 and Unified CM 3,  I can see the hostnames of the two servers (SUB2 and PUB) but the IP address displayed for both hostnames is 0.0.0.0

[justserve]

Yes the phones have correct DNS servers. I can ping both servers from the phone VLAN

[yahsiel2004]

Have you verified the services running on SUB2 and PUB? Have you verified connectivity between the phones and SUB2 and PUB?

Yosh

[Aaron Harrison]

Hi

How are the CUCM servers displayed in the 'System/Servers' menu in CCMAdmin?

Is a DNS domain name assigned to the phones?

Is the sub they are registered to the TFTP server assigned via option 150?

Can you post up a screen grab of the phone net config web page, and a download of the xml config file from CUCM?

Aaron

[justserve]

Hi,

Find below the responses:

IP address displayed for SUB1 while for the PUB and SUB2 hostnames are displayed

Domain names are not assigned to the phones.

The phones are registered to TFTP server assigned via option150. Although, the sub they are registered to is TFTP 2 while PUB is TFTP 1.

[Aaron Harrison · Accepted solution]

Hi

Do:

tftp get sepxxxxx.cnf.xml

(with the proper sepxxxxxx device name for a failing phone) and see what the names of the CUCMs are presented as.

If they are simple hostnames, then the phones probably won't be able to resolve those names, as they don't have a DNS domain assigned. Assign the same DNS domain that the CUCM hostname records are in to the phones to resolve that.

Alternatively in SYstem/Servers in CUCM, change the server references from hostnames to the IP addresses of the servers, and reset the phones.

Aaron

[justserve]

Hi Aaron,

Where do I execute the command tftp get sepxxxxx.cnf.xml?

When I included the domain names, PUB (Unified CM 3) became the standby  on the phone with its hostname and actual IP address displayed whereas  SUB 2 (Unified CM 2) ip address was not displayed though hostname was  displayed. But when I removed the the PUB from CUCM group, so that only  the subscriber servers are in the CUCM group, SUB 2 was not chosen as  the standby though the hostname was displayed on the phone, the ip  address was 0.0.0.0.

If I change the references to IP addresses, will the servers not restart. What effect will this have on database replication?

Thank you.

[justserve]

Hi Aaron,

With or without adding the domain name, the issue was resolved. In System/Servers in CUCM, I changed the server references  from hostnames to the IP addresses of the servers, and reset the phones.

However, why is it that the issue persisted when on adding the domain names and in System/Servers in CUCM the refereneces are hostnames?

Thank you.

[Aaron Harrison]

Hi

Yes - those are alternate solutions. Set the servers to IP, the phones get IP in the config file and all is well.

Alternately if the phones have the same DNS domain set as the servers, and appropriate DNS server IPs, they should attempt to resolve hostnames by appending their DNS domain name to them. I think that's what your hostname-based solution was missing.

Glad to hear all is well.

Aaron Harrison

Principal Engineer at Logicalis UK

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