DComTalk.com

Hello all,

I am designing a circuit board with Ethernet and have a real basic
question. I do not have any experience with Ethernet, so I hope my
question does not seem too silly.

I have 4 processors on a board that need to talk to each other and to
the outside world thru fast Ethernet. I have targeted a possible
Ethernet controller, the SMSC LAN91C111 (mac and phy).

One implementation would be to have 4 LAN91C111's (one to each
processor), 4 sets of magnetics, connected to an on board router, then
to another set of magnetics, then to the RJ-45 connector, etc...

This seems like a lot of unneccessary hardware. It would seem like
there would be an integrated solution with 4 processors talking to a
single controller and that controller connected to a single set of
magnetics to the RS-45 connector.

Any ideas would be appreciated,
Jim

"Jim" <jima1@verizon.net> wrote:

One implementation would be to have 4 LAN91C111's (one to each
processor), 4 sets of magnetics, connected to an on board router, then
to another set of magnetics, then to the RJ-45 connector, etc...

I'd think at the very least you could eliminate the interior
magnetics, but wouldn't it be cleaner/faster to have one processor
handle the Ethernet and have some kind of shared memory for
interprocessor communications?

William P.N. Smith wrote:

"Jim" <jima1@verizon.net> wrote:
One implementation would be to have 4 LAN91C111's (one to each
processor), 4 sets of magnetics, connected to an on board router, then
to another set of magnetics, then to the RJ-45 connector, etc...

I'd think at the very least you could eliminate the interior
magnetics, but wouldn't it be cleaner/faster to have one processor
handle the Ethernet and have some kind of shared memory for
interprocessor communications?
Yes, that is another option - thanks for the idea.