From: Hobbs (deadheadblues@gmail.com)
Date: Wed Aug 06 2008 - 23:59:24 ART
I found the problem! Narrowing it down to a problem between cat1 and cat4, I
saw cat4 sending the cdp packets. however cat1 was not tunneling these.
Turns out that "vlan dot1q tage native" was enabled on cat4.
Not really sure what cat1 was doing with the packet but it definitely wasn't
tunneling it!
Anybody know what an access port with l2protocol tunneling enabled does with
a tagged cdp packet? Do they get tagged in such a scenario?
On Wed, Aug 6, 2008 at 7:12 PM, Hobbs <deadheadblues@gmail.com> wrote:
> Hello,
> I have been working on this all day, I have got most of it to work and have
> one more little roadblock. The odd things about this is that it works one
> way. cdp, stp, lacp were all being tunneled successfully from R3 to R4.
> debug showed that R4 was receivng packets from R3 over the tunneled port.
> However the reverse is not true.
>
> [CAT4]20--------20[CAT1]24--------24[CAT2]20--------20[CAT3]
>
> The numbers above are the FastEthernet ports.
>
> Cat4 and cat3 should see each other as CDP neighbors.
> One thing about this solution is:
>
> ports 24: mode dot1q-tunnel
> ports 20 on cat1 and cat2: mode access
> ports 20 on cat3 and cat4: mode trunk
>
> Before I show the configs, I'll show that cat4 does see cat3 over port 20:
>
> CAT4#show cdp neighbors | inc CAT3
> CAT3 Fas 0/24 132 S I
> WS-C3560-2Fas 0/24
> CAT3 Fas 0/23 132 S I
> WS-C3560-2Fas 0/23
> CAT3 Fas 0/20 132 S I
> WS-C3560-2Fas 0/20
>
> However, CAT3 is not showing CAT4:
>
> CAT3#show cdp neighbors | inc CAT4
> CAT4 Fas 0/24 145 S I
> WS-C3560-2Fas 0/24
> CAT4 Fas 0/23 145 S I
> WS-C3560-2Fas 0/23
>
> It seems I just need to mirror the config that is working but I am. I'll
> show the ports in order from left to right. Pay no mind to lacp right now,
> as I do not have it on the end ports. Just the CDP I'm trying to get going.
>
> *CAT4*:
>
> interface FastEthernet0/20
> switchport trunk encapsulation dot1q
> switchport trunk allowed vlan 1-12,14-4094
> switchport mode trunk
>
> *CAT1*:
>
> interface FastEthernet0/20
> switchport access vlan 43
> switchport trunk encapsulation dot1q
> switchport mode access
> l2protocol-tunnel cdp
> l2protocol-tunnel stp
> l2protocol-tunnel vtp
> l2protocol-tunnel point-to-point lacp
> no cdp enable
>
> interface FastEthernet0/24
> switchport access vlan 43
> switchport trunk encapsulation dot1q
> switchport mode dot1q-tunnel
> l2protocol-tunnel cdp
> l2protocol-tunnel stp
> l2protocol-tunnel vtp
> l2protocol-tunnel point-to-point lacp
> no cdp enable
>
> *CAT2*:
>
> interface FastEthernet0/24
> switchport access vlan 43
> switchport trunk encapsulation dot1q
> switchport trunk allowed vlan 1-12,14-4094
> switchport mode dot1q-tunnel
> l2protocol-tunnel cdp
> l2protocol-tunnel stp
> l2protocol-tunnel vtp
> l2protocol-tunnel point-to-point lacp
> no cdp enable
>
> interface FastEthernet0/20
> switchport access vlan 43
> switchport trunk encapsulation dot1q
> switchport trunk allowed vlan 1-12,14-4094
> switchport mode access
> l2protocol-tunnel cdp
> l2protocol-tunnel stp
> l2protocol-tunnel vtp
> l2protocol-tunnel point-to-point lacp
> no cdp enable
>
> *CAT3*:
>
> interface FastEthernet0/20
> switchport trunk encapsulation dot1q
> switchport trunk allowed vlan 1-12,14-4094
> switchport mode trunk
>
> Now remember that this works in one direction from
> cat3-->cat2-->cat1-->cat4.
> The breakdown is from cat4--->cat3, specifically between cat4 and cat1 I
> believe. This is because a show l2protocol-tunnel shows 0 encapsulated
> packets for CDP on port 20.
>
> any ideas? remember it works one way!
>
> thanks,
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