svn commit: r327086 - head/sys/dev/lmc

[Kurt Lidl]

On 1/4/18 5:00 AM, Poul-Henning Kamp wrote:
> --------
> In message <3f4a7247-e711-c65a-d973-c929ac8726db at freebsd.org>, Stefan Esser writes:
>> Am 04.01.18 um 00:41 schrieb Pedro Giffuni:
> 
>> It appears to be a strange beast that uses the Ethernet chip to generate a
>> bit stream which is then converted to HDLC. Not sure whether these were used
>> for Frame Relay or to connect to the British X.25 JANET, a few decades ago.
>> Perhaps also to connect to SS7 signaling networks?
> 
> They were actually pretty versatile, we used them both for "blank"
> E1 and Nx64 scenarios, and I know they were used for Frame Relay
> several places in US.
> 
> I don't think they could do SS7 or ISDN like the MUSYCC chip could.
> 
> But nobody uses T1/E1/T3/E3 lines any more for anything...

There's thousands upon thousands of customers that attach to networks
via T1 lines, running Frame-Relay to this day.  Granted, ADSL has
captured the consumer market, but NxT1 is still popular in the
business world.  (And pretty much all the T1s in the world are
actually delivered over 2Mmbps SDSL, which is then turned into the
1.544 mbps T1 interface, but that's not really germane to this...)

As for the lmc product itself, and that driver-  David Boggs, when
working at DEC-WRL (Dec's Western Research Lab) realized that the
Ethernet controller that ran the "de" Ethernet chips could be easily
plumbed into an FPGA and used as the front-end controller for the
framer for the serial line.

In 1999 I worked with David Boggs to modernize this driver (or more
precisely, the "sbe" version of it), so it had SMP locking for
FreeBSD and BSD/OS.  Dave is really easy to work with, and we were
able to make the driver deal with Frame Relay, in addition to the
"Cisco HDLC" (aka chdlc) framing.  I don't think we attempted to
get the synch PPP stuff working, as I only had access to a T1 line
with FR signaling on it.

T1 is just an electrical standard for interface, you can do all sorts
of different signaling and protocols over that interface.

I still have this hardware (but not in use), as well as a pair of
the HSSI boards (54mbps, suitable for use with a T3 circuit).

If you just want someone to test it, I can probably lash together
two machines with these cards as the interconnect.

-Kurt