Some VoIP phones failing to register due to inactive LAN2 configuration

[F7401]

We are experiencing issues with some VoIP phones in the office (and have been for some time) and finally tracked down the root cause. We currently have a flat /16 network (yes, we are working on getting that shrunk and implementing VLANs).

Here is our config in IPO:

Our IPO does not have a cable plugged into the LAN2 port and the IP address it is assigned belongs in our DHCP range. (Not sure how it got that IP in the first place..)

So, we mirrored the port the phone is connected to on our Cisco switch and hooked up Wireshark and we were able to get a bit more info. It appears that anytime a VoIP phone tries to register with our IPO AND it's IP address is within the 10.0.1.X/24 range it sends a gatekeeperRequest to the LAN1 IP but receives a gatekeeperConfirm from LAN2. This causes it to loop back and forth and the phone gets stuck in a Discover 10.0.10.19 state. If the phone is given an IP outside of that range it registers without any issues.

First thing we tried was un-checking the "H323 Gatekeeper Enabled" box on LAN2. This did not fix the phones, however Wireshark now shows they are no longer receiving a gatekeeperConfirm, the phones are just spamming gatekeeperRequests.

I'm assuming the next thing to do would be to change/clear out the IP assigned to LAN2.. but I don't know if that is the correct solution or if there are any repercussions to look for.

Thanks!

 

[avayaguyuk]

Are you actually using the LAN2 port for anything? The issue you have is that LAN1 and LAN2 are overlapping.

LAN1 = 10.0.10.19/16
LAN2 = 10.0.1.98/24

It seems like because your handset is using 10.0.1.x range the IP Office is trying to communicate via that because its the best route to it (or so it thinks) because there is one less hop, e.g. no default gateway to pass through.

Change the LAN2 address to 192.168.43.1 (default) and it'll work OK.

 

[F7401]

We are not using LAN2 for anything, it's not even physically plugged in. I figured that too, I guess even though the IP Routes are set for LAN1 it ignores them based on like you said, less hops?

That's what I was thinking we were going to have to do. Didn't know the default IP to change it back to since as far as I'm aware, it's always been set to an overlapping IP.

Thanks!

 

[intrigrant]

Set LAN 2 to a subnet way out of range of the subnet used on LAN1 like 192.168.43.1/24, disable the gatekeeper on LAN2 and reboot.
Problem solved.

 

[amriddle01]

IP routes are not needed or even checked for the subnets the LAN ports are in, you only need routes for other networks/subnets, the others can be deleted