[c-nsp] VLAN Trunking Question

Gert Doering gert at greenie.muc.de
Wed Sep 11 07:04:08 EDT 2013


Hi,

On Tue, Sep 10, 2013 at 05:25:49PM -0400, Joseph Mays wrote:
> Catalyst A
> 
> interface FastEthernet0/1
> description to gw1.armplc
> duplex full
> speed 100
> switchport trunk encapsulation dot1q
> switchport mode trunk
> no cdp enable
> 
> interface FastEthernet0/10
> description Hatteras 1 - HN408-U
> switchport trunk encapsulation dot1q
> switchport mode trunk
> no cdp enable

My gut feeling is that you have not created vlan 808 on the intermediate
switches - if a catalyst switch sees an incoming tag it has no vlan config
for, it will drop the packet.

Depending on the catos version, you either need to go to "vlan database"
mode, or to "conf term" and then just say "vlan 808+<return>".

What helps me with this sort of problems is "show spanning-tree vlan 808"
- if that returns "no stp instance" (or something to that extent), you
have not created that VLAN yet.

Don't forget to turn off VTP while at it...  (turning off VTP is *way*
more important than turning off CDP, which we leave *on* because it helps
a lot in figuring out where that damn cable went...)

gert
-- 
USENET is *not* the non-clickable part of WWW!
                                                           //www.muc.de/~gert/
Gert Doering - Munich, Germany                             gert at greenie.muc.de
fax: +49-89-35655025                        gert at net.informatik.tu-muenchen.de
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