Etherneting a 3B1 and Sun 3/60 (it works)

thad at thad at
Thu May 23 21:17:11 AEST 1991

{Again from my hastily-scrawled notes in an attempt to catch up ...} Someone
recently asked about connecting a 3B1 to a Sun 3/60 via Ethernet.

After tonight's AT&T Silicon Valley UNIX Users' Group meeting (featuring the
SONY NEWS SVR4 UNIX Laptop (WOW! uses the MIPS R3000A chip, too)), and since I
had one of my 3B1 systems in the car, two of us went over to my office for
another matter, but I later brought the 3B1 in and put in on the office net.

The network number of the net on which the Sun 3/60 was located differed from
the network number I use in my lab, so I first tried the "obvious" things with
/etc/gateways, mucking up the /etc/hosts, editing /etc/networks, etc etc to
no avail.  In all cases, "Host is not reachable."

So a brute force technique was next tried: I changed the Internet number of
my 3B1 in /etc/hosts to be on the same net as the Sun and altered the file
/etc/lddrv/ether.rc to set the 3B1's "new" hostid on the same net as the Sun,
rebooted, and voila!  All works just perfectly, even rwhod, etc.   rlogins
worked transparently and what really impressed me was the ftp transfer rate
between the Sun 3/60 and the 3B1: an average of 45 Kbytes/sec (with a max
of 47Kbytes/sec and a min of 41 Kbytes/sec) pushing the Sun's /vmunix (1.2MB+)
back and forth across the net about 20 times.

That 45Kbytes/sec was even faster than a 12MHz IBM PC/AT whose tranceiver I
"borrowed" for the 3B1 tests (the PC/AT would get about 35-37Kbytes/sec with
the same tests).

What's even funnier is that that IBM PC/AT was running WIN/TCP 4.something
and the 3B1 is using the old WIN/3B version 1.something.  Hmmm, a multi-tasking
10MHz 68010 outperforming (again) a single-tasking 12MHz 80286; MS-DOS vadanya!

Now, I don't profess to be a TCP/IP expert by any stretch of the imagination,
but I didn't encounter much difficulty.  I do NOT understand why I couldn't
have hosts whose IP numbers were, say, 192.9.200.* talk to hosts whose IP
numbers were, say, 128.15.22.*, all connected on the same ThinNet backbone;
maybe now's the time to RTFM!  :-)

As far as TCP/IP on the 3B1 goes, everything generally seems to operate as
one would expect.  I even recently took the "whois" client and server examples
from Doug Comer's "Internetworking with TCP/IP, 2nd ed, Vol. 1" and got them
working on the 3B1 with no fuss, along with some 4.3BSD ports I did last year.
Some of this stuff DOES work with the 3B1's shared libraries (4.3BSD's ftp, for
example), and some does NOT work with the 3B1's shared libraries (the "whois"
stuff, for example).  Dunno why.

On the off-chance it might make a difference if the original poster is still
having difficulties, my "ifconfig" for the 3B1 (and all the other systems for
which I more-or-less have responsibility) does specify "trailers"; the default
setups I've seen for nearly every system (3B1, CTIX, SunOS, AIX, A/UX, IRIX,
etc.) has "notrailers".  I made those changes since the docs (yeah, I do RTFM
occasionally) stated better performance would be achieved with "trailers" re:
not having to move buffers of data back and forth (and that does appear to be

Summary: a 3B1 and Sun 3/60 (with SunOS 4.1.1) do internetwork just fine.

Thad Floryan [ thad at (OR) {decwrl, mips, fernwood}!btr!thad ]

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