Go CCIE Go!! - A Cisco Certified Internetwork Expert

No I read your questions, and thats my fault. I have to lab it up to test.
But my thoughts on question 1: Yes the forwarding behavior would be correct since you have the l2protocol-tunnel cdp. I haven’t used it in that manner without the switchport mode dot1q-tunnel. My thoughts on question 2: Yes Dest Mac will be the same.
My thoughts on question 3: Can you post your output when you do the sh cdp nei on CAT2 Fa0/23? I think its not showing BB1 as a neighbor on CAT2 Fa0/23 because you are not performing dot1q-tunneling. I don’t think a regular trunk overrides the cdp tunneling behavior but more so its not how the technology works with that particular configuration.
I have to lab it up myself to play with that scenario you have setup. Sorry on my lack up reading earlier but those are my thoughts on your question.
R/
Jonathan On Wed, Aug 6, 2008 at 11:47 AM, Hobbs wrote:
> Jonathan, it is a question. I am not looking for a command to make it work. > it is working. please read the entire email. If my question doesn’t make > sense, I can try and rephrase. > > > On Wed, Aug 6, 2008 at 10:42 AM, Jonathan Greenwood II wrote: > >> Just turn off cdp on that particular port on CAT1 connecting to BB1. “no >> cdp enable” >> >> >> On Wed, Aug 6, 2008 at 11:37 AM, Hobbs wrote: >> >>> Thank you for the reply, but I am not having any configuration issues. It >>> is only a question. I don’t want CAT1 to see BB1 as a neighbor, I am just >>> trying to understand why it doesn’t. >>> >>> I am not doing dot1q tunneling >>> >>> >>> On Wed, Aug 6, 2008 at 10:32 AM, Jonathan Greenwood II >> gwood83@gmail.com> wrote: >>> >>>> You need to change the switchport mode from access to dot1q-tunnel. >>>> >>>> On Wed, Aug 6, 2008 at 11:27 AM, Hobbs wrote: >>>> >>>>> Hello, >>>>> >>>>> I am trying get my head around a semi-complex protocol tunneling task, >>>>> but I >>>>> have some questions on the basics. >>>>> >>>>> Here’s the topology >>>>> >>>>> “Near end host”: BB1 >>>>> “Far end switch”: CAT2 >>>>> >>>>> [BB1]f0/1—–f0/11[CAT1]f0/23—–dot1q >>>>> trunk—–f0/23[CAT2]f0/1—–f0/1[R1] >>>>> >>>>> To get cdp tunneling to work (and it does work) I enable this on CAT1 >>>>> and >>>>> CAT2 access ports: >>>>> >>>>> CAT1: >>>>> interface f0/11 >>>>> switchport mode access >>>>> switchport access vlan 100 >>>>> l2protocol-tunneling cdp >>>>> no cdp enable >>>>> >>>>> CAT2: >>>>> interface f0/1 >>>>> switchport mode access >>>>> switchport access vlan 100 >>>>> l2protocol-tunneling cdp >>>>> no cdp enable >>>>> >>>>> The trunk between CAT1 and CAT2 carries vlan 100 as well as others. >>>>> >>>>> This is what I understand so far: >>>>> >>>>> BB1 sends a multicast CDP packet on it’s port to CAT1. >>>>> Since CAT1 has cdp tunneling enabled, it forwards it rather than >>>>> processes >>>>> it. Is this correct? >>>>> CAT1 sends this packet out all trunk links that have vlan 100 allowed >>>>> AND >>>>> any access ports on VLAN100. Is this correct? >>>>> The packet still has the cisco CDP destination MAC. Is this correct? >>>>> The packet is dot1q tagged and sent out port fa0/23 and still has cisco >>>>> CDP >>>>> destination MAC address. Is this correct? >>>>> >>>>> Question: >>>>> >>>>> CAT2 doesn’t have tunneling on port fa0/23. >>>>> Why doesn’t CAT2 now process this CDP packet and show BB1 has a CDP >>>>> neighbor >>>>> on fa0/23? >>>>> Does trunking override this behavior? >>>>> Does CAT2 treat this packet differently because it is a tagged CDP >>>>> packet? >>>>> >>>>> Thanks, >>>>> >>>>> >>>>> Blogs and organic groups at http://www.ccie.net >>>>> >>>>> _______________________________________________________________________ >>>>> Subscription information may be found at: >>>>> http://www.groupstudy.com/list/CCIELab.html
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