Conference 7.286::fddi

2207.0. "DEMFA and CISCO LS2020" by BACHUS::HUWAERT ("Pierre HUWAERT @BRO DTN 856-8762") Mon Jan 27 1997 11:09

One of our customer has a vms fddi cluster with two VAX 7700.
Each VAX7700 has a DEMFA.If we connect the two systems with a direct MIC cable
everything works fine.

The customer want to put a system in a separate building.So he bought a Cisco LS2020.
If we connect computer A to the LS2020 the 'PHY' led flickers and then stay on; the
connection is made.
If we do the same with computer B the 'PHY' led flickers forever.(no connection)
We already change the mic cable,the DEMFA (T2027) the internal cable nad the bulkhead
the XMI slot and the XMI power supplies without any succes.
We measure the light signal and get for cisco and demfa around -16 -18 dB which is in the
specifications.

If I connect the light transmitter from the cisco to the light receiver of the demfa (from conmputer A)
and then measure the light signal out of the demfa we don't get a stable signal;
it flickers between -16 -21 -16 -23 -16 -25 -16 -28 -16 -31 .......-16 -50 -16 -54 
and then stay at -16.It seems that the demfa try to get a match with the cisco.

If I do the same but with computer B the signal filckers between -16 -22 -16 -22 -16 -22 -16 -22...
So only between two values.

I noticed that the digital signal on pin 11 on the lower row of the bulkhead in different
on the two computer.On computer A (the good one) we have square pulse at 300 ms and on 
computer B the square pulse is at 120 ms.

On computer A (the good one) the demfa firmware revision is V2.0 .Following different
notes in this conference it has to be downgrade to V1.4.

The computer B demfa is at V2.1 version which is a kind of V1.4 for E09 module if I
understand well some previous notes.

We planned now to try a version V2.0 in computer B and a V2.1 in computer A.

Is there some release notes for the V2.0 and for ths V2.1?

Is the CISCO LS2020 used somewher else?

Thanks.

Pierre.