🚀 go-pugleaf

In article <GAH.92Nov18150548@HP370T.trc.mew.mei.co.jp>, gah@trc.mew.mei.co.jp (Gary A. Hildebrand) writes:
|>All,
|>
|>Let's imagine a hypothetical case.  You want to implement minimal data
|>transport over FDDI, with just enough MAC/SMT support for somewhat robust
|>LLC, and nothing more.  You don't care about MIB management or SRF's at
|>this point.  Anyone who's read through the FDDI standards can tell you what
|>is perscribed as mandatory and what is optional, but how much can you
|>really get away with?  In a real implementation, are any SMT frame services
|>absolutely essential for keeping the ring up?  NIF frames immediately come
|>to mind.  What about the many different types of CMT services and
|>functions?  I would suppose that most nodes would cause trouble if they
|>didn't all implement full RMT and PCM support in or out of the MAC
|>chip/software layer.

If you don't care about standards conformance, and your network is small
enough that you don't feel a need to worry about some of the fancier
fault recovery mechanism, you could cut quite a lot.  You need MAC, PHY,
and PMD as specified, of course.  In SMT, you need very little.  PCM is
necessary, because that's how you talk your neighbor into letting you join
the ring.

However, your node and the ring will work just fine (in the sense of allowing
user data traffic to proceed -- though NOT in the sense of being manageable)
without ANY SMT frames at all.  Of course, you can't get a ring map, not
even from fully conforming stations, unless you at least do NIF by the rules.
And so it goes in general ... the more of the required parts are in fact
present, the more your node resembles a normal, fully manageable, FDDI node.

|>This case is actually not so hypothetical.  I'm wondering about PC FDDI
|>interface cards such as the one from Network Periperals.  Does the small
|>NDIS driver loaded and/or firmware on the board actually implement all the
|>ANSI-draft-standard mandatory components of the MAC/SMT protocols that are
|>not covered by the National chipset, or just a bare minimum functional
|>subset?  Unfortunately, this board comes with little or no technical
|>information.

I don't know about that PC card.  But there is at least one (the DEC one)
where the SMT support is done entirely by firmware (in a 68000) on the
adapter itself.

|>Gary Hildebrand

	paul koning