[c-nsp] Spanning-Tree question

[Ben Steele]

No worries, also you can disregard my suggestion about load balancing  
your "2" vlans, as I just realised after I sent it we are only talking  
about a single VLAN here, note to self to stop multitasking! :)

Ben

On 01/02/2008, at 4:08 PM, Aaron R wrote:

> Yes I probably disconnected it before this as the cpu went crazy @  
> like 90%.
>
>
> Thanks for your suggestions.
>
> Cheers,
>
> Aaron.
>
> -----Original Message-----
> From: Ben Steele [mailto:ben at internode.com.au]
> Sent: Friday, February 01, 2008 2:31 PM
> To: Aaron R
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Spanning-Tree question
>
> It should eventually go into a blocking state as the port still
> participates in STP in portfast mode, this can take 30-50 seconds
> though, not sure if you've left it that long?
>
> On a side note, if you have Administrative control over both devices
> and they are in different VTP domains already why not run the links
> between the 2 business's as Trunks with vlan filtering, that way you
> can load balance the 2 vlans with priority over the trunks as well as
> redundancy.
>
> Ben
>
> On 01/02/2008, at 3:51 PM, Aaron R wrote:
>
>> 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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>>
>