Change Subnet mask of CUCM and UCCX

[Abdelrhman Elmenyawe]

Does change Subnet mask for CUCM, UCCX from /16 to /24 will impact phones or anything else?

[Elliot Dierksen]

Your network infrastructure must be changed to support that change of subnet mask, or everything breaks. I know that is pretty obvious, but I didn't want to leave it unsaid. Next, it depends on the version you are running. If you are running a version that is integrated with smart licensing, you should be fine. If not, it will change things. Here is an excerpt from the CCX V.11 page describing how the license MAC is calculated.

License MAC

It is the unique identifier that is unique to every UCCX server. It is NOT the physical address/MAC of the Network interface of the server.

In order to find yours, navigate to UCCXApplication Administration > Licenses > Display page.

Or, with the Command-Line Interface (CLI), you can run the command: show status

The License MAC of the UCCX is calculated with these parameters unique to every server.

Any change in any of these parameters can invalidate the License MAC of the server, and the licenses will have to be rehosted by Cisco Licensing.

    Time zone
    NTP Server 1 (or ‘none’)
    NIC speed (or ‘auto’)
    Hostname
    IP Address
    IP Mask
    Gateway Address
    Primary DNS
    SMTP Server (or ‘none’)
    Certificate Information (Organization, Unit, Location, State, Country)

Example: Here, this is a demo license with License MAC "FFFFFFFFFFFF" 

INCREMENT CRS_PRE_SEAT cisco 11.0 permanent uncounted \
 VENDOR_STRING=<count>100</count><MAC>FFFFFFFFFFFF</MAC> \
 HOSTID=ANY \

It would probably affect CUCM too. As long as you have active support, you should be able to contact TAC and get the licenses updated after the change. Make sure you do this during a maintenance window in case you have to reboot.

[Abdelrhman Elmenyawe]

thanks Elliot,

i am using 12.5 for CUCM and UCCX with smart licensing already. 

and of course, the network first will be changed so that the voice servers need to be updated.

[Nithin Eluvathingal]

Making changes to network configuration will cause the cucm network to restart which obviously cause the phones to reregister.

since you are on smart smart licensing version , if you have any issues with the licensing you can deregister and reregister.

[juancastillo]

Hello,

What if we have CUCM/PLM 11.5, would the subnet mask change cause a need for re-hosting the licenses?

For us it's a subnet mask change required on the CUCM Publisher (PLM) server.

Thanks,

[Elliot Dierksen]

If you are using PLM/ELM or smart licensing, that shouldn't be a problem. CCX is a problem until you get to smart licensing because it uses node locked licenses that are tied to the first DNS server and several other options.

[juancastillo]

ok...

Thanks a lot!