From: Hobbs (deadheadblues@gmail.com)
Date: Wed Aug 06 2008 - 13:37:51 ART
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,
>>
>>
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>>
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