[SI-LIST] problems about 1-to-2 FE connection

Hi,experts:

Very tough problem for me in Ethernet redundancy design.

In our backplane, we use an illegal Ethernet switch board redundancy scheme. 
our processor board has one FE(Fast Ethernet), and two switch boards are 
resided in backplane for redundancy. the processor board FE connect to the two 
switch board at the same time, but one switch board is in standby state(The PHY 
on this board is tristated), so the processor board FE will communication with 
the active switch board. But you know, FE must have a transformer for 
isolation, so the processor board FE has 1-to-2 transformer connection because 
of the two switch board on this FE. This will cause to Ethernt singal 
distortion and this is not compliant with standard, and some processor boards 
can not transmit data with very high speed.

If we use AC104QF from Broadcom, maybe 2 boards FE will fail among 12 boards, 
other 10 boards FE are very normal.

But if we use AM79C875KI from AMD, maybe 5 boards FE will fail among 12 boards.

Our redundancy scheme is not changeable, so how to let the FE work nomal in 
this situation?
Does anyone encounter similar problems?

Urgent, I very appreciate your help and information.


Thanks!

Peter

UTStarocm
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