switches rebooting

[browolf]

we have a problem with 3com 48 port superstack 3 3250 switches randomly
resetting. Its happening all over the place and 3com are refusing to
acknowledge a problem. A good illustration is: in a cabinet we have
3x3250s and 1x superstack 3 3226

the main network comes in on a fibre connected to a gigabit port & an
adapter. the switches are chained using utp on the gb ports

if the cabinet is configured thus:
fibre > 3226 > 3250 > 3250 > 3250

the first (and only the first) 3250 randomly reboots

if the cabinet is configured:

fibre > 3250 > 3250 > 3250 > 3226

we have the same problem. the first 3250 randomly reboots. it doesnt
seem to matter which 3250 is which.

in other smaller cabinets with only one or two switches we've
temporarily fixed the problem by replacing the 3250 with a 24 port 3226
and having the inputs spread around. this seems to run ok.

we're in the process of getting hold of a filtered ups to try. The Firmware is 1.20.00.01

any ideas on whats going on or experienced anything like this

cheers

Andy

[CyberNerd]

You shouldn't really cascade switches in that way, it makes them less efficient.

enable STP and have them set up so each switch is directly connected to the switch with the fibre module.
____3250
|
fibre > 3250
|
|____3250
|____3226

I suspect this isn't a fault with the switches - I have seen our 3250 and 3226's reset (but not reboot) when they there is a fault on another, seemingly unrelated switch - Removing an old 100Mb Hub that we'd forgotten about fixed our problem. Good plan with UPS, Ethereal and Nagios may also help diagnose.

[CyberNerd]

sorry my ascii art isn't really up to it

[ChrisC]

_____
|3226|
|____|
| | | |
| | | |__3250
| | |__3250
| |___3250
|___Fibre

Would be how I would do it, I think thats what you meant?

Chris

[CyberNerd]

turner prize nominations go to..

thanks, thats what I meant

[ChrisC]

s'nothing compared to ascii star wars!

Chris

[browolf]

_____
|3226|
|____|
| | | |
| | | |__3250
| | |__3250
| |___3250
|___Fibre

Would be how I would do it, I think thats what you meant?

Chris

the ony problem with that is that there won't be enough gigabit ports to go around. at least with the cascading they're all connected together on gigabit. whats this stp thing?

[marco84]

STP....

Spanning Tree Protocol prevents loops in the network affecting traffic. IE broadcast storms.

[Ric_]

STP = Spanning Tree Protocol

Basically STP means you can connect a switch up to two others and it will use the quickest route to send your traffic down. You don't actually need it in this instance.

The 3COM manuals have some good explanations about STP and pretty pictures IIRC.

[ChrisC]

Spanning tree protocol on a managed switch will detect a loppback on a connection and isolate it from the network.

Chris

[plexer]

Cascading them is not the best way to set them up. They may all be plugged into a gigabit port but that's all.

Ben

[browolf]

Im not sure my NM will go for the non-cascaded option

STP seems to be enabled already. must be on by default.