Aivars, Best practice would be to remove VLAN 1 from the list of trunked VLANs.
Mike On Mon, Dec 10, 2012 at 10:39 AM, Aivars <[email protected]> wrote: > Hi, > > I thought that CDP essence is to help understand what device you > have at the other end of the wire no matter what. You just plug one > end of the cable into one box and the other end into another and > you get your CDP neighbors. Besides other side usage like in IP > phone communication with switches this is why anybody would use CDP. > Right? > > Up until this morning I also thought that CDP frames are always sent > untagged. This is the way I would do it. Well, I was wrong. Actually > on Catalyst switches CDPs are sent in vlan 1. If you make some other > vlan native on a trunk port, CDPs are sent with dot1q tag "1". vlan > dot1q tag native will also do the same trick. > > Now imagine a brand new shiny IOS-XR box, ASR9k for example. If it > has no subinterface configuration with encapsulation dot1q 1, CDP > will be broken. It will send CDPs with no tag and Catalyst will be > happy about it. It will show ASR as CDP neighbor. ASR instead > doesn't now what a hell tag "1" means and drop these frames. > > Cisco thinks - this is expected behavior. > > What do you guys think? Is this a bug or a feature? Should it remain > as it is? > > Aivars > > _______________________________________________ > cisco-nsp mailing list [email protected] > https://puck.nether.net/mailman/listinfo/cisco-nsp > archive at http://puck.nether.net/pipermail/cisco-nsp/ > _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
