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Network performance issues with 3500XL

Hi guys,

This one has been puzzling me for some time now, and I was hoping for a bit of advice from the experts!

Currently we have 4 Cisco 3500XL switches, connected like so:

office1.switch.net--------office2.core.switch.net--------office2.switch1.net--------office2.switch2.net

Not the best representation of how our switches are connected, but the best I could manage :)

Okay, now onto our problem:

We have all servers connected to the "core" switch, and then users are split across the other three switches. We don't have any VLAN in place.

here is a brief run down of our configs (I've only copied one config into this post, since they are mostly identical - except for management IP/hostname).

Reply to
Jon Fanti
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Looks like a spanning tree loop, if it is then you'll probably have small outages on the network. If so you should remove the redundant links from your network. Look at how you've configured the links between the switches. Here's a link from CCO

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the spanning tree parameters also and find out where the root bridge is too.

Reply to
Pat D

Hi John, are you sure your cabling and config is like you stated in your mail? Your problem looks like a bridging loop leading the big amounts of broadcast storms and frames switched to the wrong ports. But therefore you must have cabling redundancy and a misconfigured spanning tree. For example if you configure spanning-tree uplinkfast on all switches or something like that. Do the LED's on the switches flicker like hell even if there's nobody working? Try investigating in that!!

good lick Horst

Horst Wagner (CCIE# 7975, CCSI# 20806}

Konkret Netzprojekte GmbH Friedrich Mohr Str. 14

56070 Koblenz Germany Tel: +49 261 80091 0 Fax: +49 261 80091 49 Email: snipped-for-privacy@netzprojekte.de Web:
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Reply to
Horst Wagner

storms and frames switched to the wrong ports. But therefore you must have cabling redundancy and a misconfigured spanning tree. For example if you configure spanning-tree uplinkfast on all switches or something like that.

Hi all,

Well I made some changes:

I added "spanning-tree portfast bpdguard" as a global configuration to all my switches. Then on ports that are attached to single hosts (PC or server) I added "spanning-tree portfast and switchport mode access". For the moment that seems to have fixed our issues.

I did double check the connections on the uplinks - cables have a way of moving themselves around! But it's still connected as I described (so no loop round).

Thanks all for the kind advice,

Jon.

Reply to
Jon Fanti

This is not at all good.

The port FA 0/1 is implicated in this issue. It appears to be part of a loop.

Do you have any windows servers (or other) configured with Dual NIC's and _bridging_?

What about wireless? Do you have any of that?

You would apper without question to have a loop anyway.

If you do a show mac-address you will see what devices the switch thinks are on which port.

End station ports should have onlt one address and ports that link switches will have many addresses.

You can then perhaps find out which port (if any) is incorrectly connected.

Reply to
anybody43

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