From: Jonathan Greenwood II (gwood83@gmail.com)
Date: Wed Aug 06 2008 - 14:02:37 ART
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 <deadheadblues@gmail.com> 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 <gwood83@gmail.com>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 <deadheadblues@gmail.com> 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 <deadheadblues@gmail.com>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
>>>>>
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