From: Hobbs (deadheadblues@gmail.com)
Date: Wed Aug 06 2008 - 14:09:15 ART
Thanks. I admit its hard to ask a question, when your not sure how to ask it
:)
I will be labbing it again in a few hours in some online rack time. These
are notes from my last session and I wanted to get a good understanding
before doing it again. fyi, it is actually the beginning of ipexpert's
version 10, volume 2, section 5 on l2 protocol tunneling. There will be a
couple more switches involved, but this is just the beginning.
it's a very interesting lab...just having a hard time grasping the concept.
On Wed, Aug 6, 2008 at 11:02 AM, Jonathan Greenwood II <gwood83@gmail.com>wrote:
> 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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