Thank you for the clarification. In looking at various documents, there is a lot of confusion. From what you are stating:
Access Port - sent on the VLAN for which interface is configured Trunk Port - sent on VLAN 1, whether or not VLAN 1 is tagged and whether or not VLAN 1 is allowed and in a spanning-tree forwarding state for that port Is that another way of putting it? That is different than my understanding has been (where CDP is sent untagged on an access or trunk port - period.) I just did a packet capture on an interface connected to a WLC. That interface only allows specified VLANs (which don't include VLAN 1) and a separate native VLAN (which is 999 in this case, which doesn't even exist as a VLAN on the switch.) In the packet capture, CDP was tagged with VLAN 999 when coming from the WLC. Everything else was tagged with the Management VLAN (no clients currently on the WLC.) I appreciate your help in working through this, both for understanding as well as for proper documentation on Cisco's site. Jason Boyers - CCIE #26024 (Wireless) Technical Instructor - IPexpert, Inc. Mailto: [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Aaron Leonard Sent: Wednesday, September 21, 2011 1:27 PM To: [email protected] Cc: [email protected]; [email protected] Subject: Re: [OSL | CCIE_Wireless] CCIE_Wireless Digest, Vol 30, Issue 16 So the docs http://www.cisco.com/en/US/docs/wireless/access_point/12.4_10b_JA/configurat ion/guide/scg12410b-chap17-cdp.html say: "CDP is sent on the lowest VLAN number configured on the access point. When more than on VLAN is used in a wireless network, Cisco recommends that the lowest VLAN number configured be used as the native VLAN" This is not quite accurate ... here's the *real* story on how WNBU IOS sends CDP: * if the LAN interface is not configured for VLANs (dot1q subinterfaces), then CDP is always sent untagged of course * if the LAN interface is configured for VLANs, then CDP is always sent in VLAN 1: o if VLAN 1 is configured as the native VLAN, then CDP is always sent in VLAN 1 (i.e. untagged) o otherwise - regardless of whether VLAN 1 is explicitly configured on the AP - CDP is sent tagged in VLAN 1 Pretty simple, really! References: CSCef35717 CDP Packets not sent over non-1 Native VLANs I'll file a doc bug on this. Cheers, Aaron _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
