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Procurve 2824 and 2650 with IBM Cabling system (ICS)

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Procurve 2824 and 2650 with IBM Cabling system (ICS)

We are using 2824 (Server Room) and 2650 (Workstations) Switches and connect the Workstations and Printers with Shielded Twisted Pair Cabling System (IBM ICS)using BATM Impedance Matching Devices (Balun) BA1236/S. The Speed is 100 MBit. This works fine, but we have one big Problem. If only one Balun on the Worksation Side is removed, on this link the Transmit Pair is shortened with with the Receive Pair by the ICS Connector.
In this case, the link on the switch produces looping frames and the whole network goes down until the Balun is inserted again.
Cisco Documentation says to this:
Transmit Pair to Receive Pair Shorting
The IEEE 802.5 UDC contains shorting bars that cause the Transmit contacts to be shorted to the Receive contacts when the connector is not plugged in. This "wrap path" is used to maintain the integrity of the ring when ring segments are disconnected, but it can potentially cause problems when used in Ethernet networks. This type of connector can cause a full-duplex Ethernet port, for example, to receive its own transmitted frames if the connector is not plugged in. Worse, if the port is part of a switch with a shared buffer design, these looping frames may adversely affect the entire switch. Fortunately, this condition can be detected and circumvented by software in most switches.

This problem has been addressed in all Cisco Ethernet switches and, although the switch behavior is somewhat different from switch to switch, the condition is handled without serious network impact.

I have tested this receive pair shorting using a NORTEL BayStack 350/24T Switch. This switch has no problem handling the receive pair shorting, only approx. 1 packet per second is transmitted, and the network continues operating without any problem.


Is it possible to configure the ProCurve Switches that they can handle this Transmit to Receive Pair Shorting properly?

If there is no circumvention for this problem, I will have to replace my ProCurve Switches by NORTEL or CISCO, because they seem to be more intelligent.
Sietze Reitsma
Respected Contributor

Re: Procurve 2824 and 2650 with IBM Cabling system (ICS)

You need to configure the spanning-tree protocol. According to me info this only works for the old 802.1D protocol.

You need to put the clients on fast-port.

Hopefully this works.

Re: Procurve 2824 and 2650 with IBM Cabling system (ICS)

Thank You!

Changing Spanning Tree from RSTP to STP eliminates the looping problem. I also set the ports from normal to fast mode because otherwise there would be a problem with dhcp.

Greetings from Bavaria
and Thank You again!

Re: Procurve 2824 and 2650 with IBM Cabling system (ICS)

Problem solved.