CDP will operate, even if VLAN 1 is not allowed on a trunk interface. It is sent as an untagged frame from one device to another, even if the native VLAN (whatever it is) is not allowed on the trunk. Try this for a test:
1. Cable a connection between 2 switches 2. Configure another VLAN (say 10) on those switches 3. Configure the switchport on each of those switches used to connect to each other as a trunk port, with the VLAN from #2 as native 4. Only allow another VLAN which has not been configured on the switch (say VLAN 999) to pass between the switches The switches will still see one another as CDP neighbors. You can verify the CDP packets are passing with the debug cdp packets command. It won't matter what VLAN is set as native or allowed. Jason Boyers - CCIE #26024 (Wireless) Technical Instructor - IPexpert, Inc. Mailto: <mailto:[email protected]> [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of Leigh Jewell Sent: Tuesday, September 20, 2011 1:19 AM To: [email protected] Subject: [OSL | CCIE_Wireless] Vlan 1 on trunks for CDP Is anyone leaving vlan 1 on WLC trunks for CDP to operate ? Cheers, Leigh
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