Change in CDP handling in recent IOS updates?

[Lundah]

Anyone know if Cisco's done something different with CDP and COS Priority in the latest round of IOS updates? I work for a VOIP hardware vendor, and we've run into a snag with IOS 12.2(40)EX apparently changing the COS value communication with our IP telephones.

Normally, when a switch (in my case, a 3560) sends the VLAN information to the IP set via CDP, the set should default the COS to 5. I've found that after upgrading the 3560 to 12.2(40)EX, now the IP phone comes up with a COS value of 0. Same firmware on the IP phone and it's associated server, the only change was the IOS on the switch. The funny thing is, if I use either an older IOS version on the switch (12.2(25)SEE), or an older firmware on the IP telephone, it comes up fine. Anyone got any ideas?

 

[ADB100]

I am a bit lost as to where you are looking and seeing the CoS of 5? Are you spanning a port and monitoring with a sniffer or is it some show commands you are looking at?

Andy

 

[Lundah]

Sorry, the debug on the IP phone itself shows me the settings. As I mentioned, since in this case CDP is only sending the VLAN, the IP phone should be defaulting to COS 5. I check the debug info on the phone, and it's 0. I have a hunch it may be a bug in the phone firmware, but that doesn't explain why the issue didn't crop up until the IOS was upgraded.

 

[ADB100]

How do you display the debug on the phone? Is it via the Web interface? How are your switchports configured?

Andy

 

[Lundah]

It's a Mitel IP phone, I can go in and look at all of the settings on the phone. I don't know how the ports are configured, that's someone else's responsibility. I'm just trying to figure out why the IP phones are coming up with the wrong COS after the IOS upgrade on the switch.

 

[olbs]

Many IP handsets get these settings via DHCP options or TFTP a script file on boot, these handsets don't or can't do similar?

Relying on a proprietry protocol to recieve this info doesn't seem to be the most sensible way to do it.

 

[Lundah]

The sets are capable of receiving the information via DHCP, but for whatever reason, the network was not set up this way. Had it been up to me, it would be done differently, but this is the setup that I inherited.

 

[Lundah]

Found our problem. LLDP was enabled by default in the new IOS load that was loaded to the 3560's. Since there was no configuration for LLDP, it defaulted the settings to 0, and the IP phones place priority on that data over CDP and DHCP settings.