Re: VTP PRUNNING BROUGHT NETWORK DOWN!!!

Thanks

Thomas Perrier <thomas_at_perrier.name> wrote:

On Sun, Oct 24, 2010 at 5:42 AM, Marcin Zgola <MZgola_at_netrixllc.com> wrote:
> Guys, bizzare situation for one of my clients.
>
> 4 7600 switches, 2 L3 (acting as) and 2 L2 (acting as) all in HSRP mode. Few VLANs on L2 are also L3, and there is a VLAN 500 that is setup between these routers as a default gateway. HERE
>
> L3: R1---R2
> | |
> R3 R4
>
> so R3, and R4 in HSRP theyhave 10 vlans that have not been migrated to L3 yet, so in order to go out to the internet they have to go through R1 or R2,
>
> there is a VLAN 500 on all of the routers, and R3,and R4 have ip route 0.0.0.0 0.0.0.0 10.5.100.1 (HSPR ip address for R1 and R2)
>
> when we enable VTP pruning and L2 R3 is the server, VLAN 500 got pruned and internet went down. R1 and R2 are setup in transparent mode.
>
> Why would that vlan get pruned from the trunk?
>
> any ideas..

Not bizarre at all, it's working as designed! Never activate pruning
between VTP enabled and VTP disabled (transparent) switches. From the
VTP section of 3560 config guide:

"VTP pruning is not designed to function in VTP transparent mode. If
one or more switches in the network are in VTP transparent mode, you
should do one of these:

Turn off VTP pruning in the entire network.

Turn off VTP pruning by making all VLANs on the trunk of the switch
upstream to the VTP transparent switch pruning ineligible. "

-Thomas

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Received on Sun Oct 24 2010 - 07:25:39 ART