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How to deal with a loopback cable on HP 5300xl switches?

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Anders Dahlgren
Occasional Contributor

How to deal with a loopback cable on HP 5300xl switches?

Hello,

At one of my sites I've converted a IBM Token Ring cabel system to ethernet with baluns. My problem is that sometimes a balun is removed by accident. This makes RX and TX short-circuited to each other. The Procurve switch sees this as a loop and I get a broadcast storm. Spanning tree or broadcast-limit doesn't resolve or handle it. How do I deal with this problem?

Tonight I've tried a Cisco 2950 switch. The Cisco-switch disables the port whith %ETHCNTR-3-LOOP_BACK_DETECTED and the port enters error disable state %PM-4-ERR_DISABLE. Can the same thing be done in the Procurve switch?

More information about the problem can be obtained here: http://www.cisco.com/en/US/products/hw/switches/ps628/products_system_message_guide_chapter09186a00800c81b4.html#xtocid6
and here: http://www.atm.tut.fi/list-archive/cisco-nsp/msg08842.html

Best regards
Anders Dahlgren
2 REPLIES
Sietze Reitsma
Respected Contributor
Solution

Re: How to deal with a loopback cable on HP 5300xl switches?

did you try turning on the default spanning-tree or the old 802.1D? Turning on the old 802.1D version could be a solution (not tested). It works on the 2600 and 2500 series.

There are also solutions to change the wall-outlet so that this inhabit will not happen again. Your cable installation provider should have solutions for this.

But hopefully turning on 802.1D will help.



Anders Dahlgren
Occasional Contributor

Re: How to deal with a loopback cable on HP 5300xl switches?

Thank you!

When I tried a while ago I did it with RSTP, without success. Today I did it with 802.1d STP in my lab - and it seems to work!

We are also seeing a log of duplex mismatches. This might be caused by our baluns. At the moment we are trying another brand of baluns. As a last resort we might, as you suggest, replace the wall-outlet to a RJ45 with integrated balun.

Thanks
/Anders Dahlgren