[c-nsp] Spanning-Tree question

[Aaron R]

Yes some access ports were portfast! Silly me!

If any of those access ports are in port fast does this mean that spanning
tree will not work properly? I know portfast will put the ports into instant
forwarding mode but it should still receive bpdus in order to make a
decision on what ports are blocked / forwarding yes? Or because they are
forwarding straight away it doesn't listen to these bpdus in order to make
this decision.

Cheers,

Aaron. 

-----Original Message-----
From: Ben Steele [mailto:ben at internode.com.au] 
Sent: Friday, February 01, 2008 2:08 PM
To: Aaron R
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Spanning-Tree question

Do you portfast enabled on those access ports?

On 01/02/2008, at 3:31 PM, Aaron R wrote:

> Hi Guys,
>
>
>
> Ive got a problem that I am hoping someone can have a look at. I  
> currently
> have four 3750's. Two belonging to one business unit and two  
> belonging to
> another. Each group of switches is running a separate VTP domain /  
> VLAN
> database.
>
> I am running PVST however when I connect the final link between the  
> four
> switches there is a loop and spanning tree doesn't block any of the  
> ports.
> Would anyone have any clue as to why this would be happening? Could  
> it have
> something to do with the link between the Business units being on  
> separate
> VLANs? We don't want the possibility of VLAN corruption occurring  
> hence the
> different VTP domains. Currently I am shutting down one of the  
> uplink ports
> to Business A to remedy this problem. Please see the diagram below.
>
>
>
> Cheers,
>
>
>
> ------------------------                          
> ------------------------
>
> | 3750 Switch 1  |------- Trunk ------ | 3750 Switch 2  |
>
> |  Business A     |                        |  Business A     |
>
> -------------------------                         
> -------------------------
>
>           |   VL 50                                   |   VL 50
>
>
>           |                                              |
>
>           |   VL 100                                 |    VL 100
>
>
> ------------------------                          
> ------------------------
>
> | 3750 Switch 3  |------- Trunk ------ | 3750 Switch 4  |
>
> |  Business B     |                        |  Business B     |
>
> -------------------------                         
> -------------------------
>
>
>
>
>
> Aaron.
>
>
>
>
>
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