xilinx gigabit MAC core full vs half duplex

[Matthew E Rosenthal]

Hi all, quick question regarding full vs half duplex.
i have a desktop PC with a fiber ethernet card connected to a memec vp20
board with sfp connectors built in. If I connect up this card to another
fiber card my BSD box says it is running at full duplex, but when i
connect it up to the memec board with a xilinx gigabit MAC core it only
runs at half duplex.
Can someone explain why this is?
Is it in configuration of the gmac core or is it the gmac core itself?

thanks

Matt

 

[Marc Randolph]

Matthew E Rosenthal wrote:

Hi all, quick question regarding full vs half duplex.
i have a desktop PC with a fiber ethernet card connected to a memec vp20
board with sfp connectors built in. If I connect up this card to another
fiber card my BSD box says it is running at full duplex, but when i
connect it up to the memec board with a xilinx gigabit MAC core it only
runs at half duplex.
Can someone explain why this is?
Is it in configuration of the gmac core or is it the gmac core itself?

thanks

Matt

Howdy Matt,

Have you tried looping them on themselves to see if you can isolate the
offender? And/or you could plug each into a known good device (like a
GbE switch)?

Although half-duplex is technically possible with GbE, it is never done
in practice. Hopefully the Xilinx core doesn't waste too many LUTs
supporting it.

Marc