Hello gang:

The other day, I was rewiring something and I noticed an amber light
in one port of my 2950, after investigating I found out that it
stopped forwarding because maybe it detected a loop and disabled by
STP?

Anyway, it brought down that port and activated the one new cable I
plugged in. The network went down for a little bit then came up, I
suppose it was now using the new cable.

Is there a way to overcome this? I don't want to bring the network
down just because the Catalyst detected a loop in the network, maybe
if it sees two links to the same upstream hub, it shoud load balance?

Any help, suggestion, education is greatly appreciated!

TIA

J.

"John" <vo@eudoramail.com> wrote in message 
news:184ae3db.0409160835.5c247d15@posting.google.com...
> Hello gang:
>
> The other day, I was rewiring something and I noticed an amber light
> in one port of my 2950, after investigating I found out that it
> stopped forwarding because maybe it detected a loop and disabled by
> STP?
>
> Anyway, it brought down that port and activated the one new cable I
> plugged in. The network went down for a little bit then came up, I
> suppose it was now using the new cable.
>
> Is there a way to overcome this? I don't want to bring the network
> down just because the Catalyst detected a loop in the network, maybe
> if it sees two links to the same upstream hub, it shoud load balance?
>
> Any help, suggestion, education is greatly appreciated!
>
> TIA
>
> J.

Spanning tree is supposed to work this way... if you want 2 physical links 
between switches you should channel them.

BL
-- 
There is nothing more frightening than ignorance in action. - Goethe

"Buzz Lightbeer" <buzz.lightbeer@spam.dsl.pipex.com> wrote in message 
news:4149cbfd$0$20247$cc9e4d1f@news-text.dial.pipex.com...
> "John" <vo@eudoramail.com> wrote in message 
> news:184ae3db.0409160835.5c247d15@posting.google.com...
>> Hello gang:
>>
>> The other day, I was rewiring something and I noticed an amber light
>> in one port of my 2950, after investigating I found out that it
>> stopped forwarding because maybe it detected a loop and disabled by
>> STP?
>>
>> Anyway, it brought down that port and activated the one new cable I
>> plugged in. The network went down for a little bit then came up, I
>> suppose it was now using the new cable.
>>
>> Is there a way to overcome this? I don't want to bring the network
>> down just because the Catalyst detected a loop in the network, maybe
>> if it sees two links to the same upstream hub, it shoud load balance?
>>
>> Any help, suggestion, education is greatly appreciated!
>>
>> TIA
>>
>> J.
>
> Spanning tree is supposed to work this way... if you want 2 physical links 
> between switches you should channel them.


Hi all:

Thanks for the info. I read some stuff on Cisco website about EtherChannel.
My question is:  My provider is giving the pair from a "Cisco Box" will I 
still
be able to do EtherChannel? does it have to be from another Catalyst Switch?

Thanks,
J. 

On Sat, 18 Sep 2004 22:07:13 GMT, "John Vo" <eagle@eagle.net> wrote:

>
>"Buzz Lightbeer" <buzz.lightbeer@spam.dsl.pipex.com> wrote in message 
>news:4149cbfd$0$20247$cc9e4d1f@news-text.dial.pipex.com...
>> "John" <vo@eudoramail.com> wrote in message 
>> news:184ae3db.0409160835.5c247d15@posting.google.com...
>>> Hello gang:
>>>
>>> The other day, I was rewiring something and I noticed an amber light
>>> in one port of my 2950, after investigating I found out that it
>>> stopped forwarding because maybe it detected a loop and disabled by
>>> STP?

What did the log on the switch say?  "show interface" or "show
spanning-tree" should give yu a give clue as well.


>>> Anyway, it brought down that port and activated the one new cable I
>>> plugged in. The network went down for a little bit then came up, I
>>> suppose it was now using the new cable.
>>>
>>> Is there a way to overcome this? I don't want to bring the network
>>> down just because the Catalyst detected a loop in the network, maybe
>>> if it sees two links to the same upstream hub, it shoud load balance?

Would you rather bring down the network for a longer period of time
due to the loop?


>>> Any help, suggestion, education is greatly appreciated!
>>>
>>> TIA
>>>
>>> J.
>>
>> Spanning tree is supposed to work this way... if you want 2 physical links 
>> between switches you should channel them.

Or if you're happy with just a redundant link, let spanning-tree do
it's job. That's what it was originally designed for. The loop
prevention was a beneficial side-effect.  You might also consider
setting some of the other options so that it prefers one link over the
other and protects your uplink (rootguard).  For the host connections,
spanning-tree portfast is almost essential if you run dhcp.

>
>Hi all:
>
>Thanks for the info. I read some stuff on Cisco website about EtherChannel.
>My question is:  My provider is giving the pair from a "Cisco Box" will I 
>still
>be able to do EtherChannel? does it have to be from another Catalyst Switch?


Generally, yes you'll need the same manufacturer.  In your case, I
believe you can do etherchannel with most of the newer Cisco switches.
If you are trunking and using multiple vlans, you can assign specific
vlans to each trunk.