[net.unix-wizards] help with DMR link, please

miorelli@pwa-b.UUCP (Bob Miorelli) (11/05/85)

I need help setting up a Unix network using a pair of DMR's.
This is a vanilla 4.2 system and just got a second machine (also 4.2)
about 3 miles away.  We want to network them over a pair of
DMR's at 56K baud.

I'm really not sure how to configure things.  I did specify
inet, loop, ether, and pty in my config file (pseudo-devices)
and put the dmc specification in.  Unix does recognize the dmc0
at boot time.  Now what?? I'm not sure what goes in the /etc/hosts
file (including how to specify the lopback).  I did add a line
to my rc.local of the form "/etc/ifconfig dmc0 `hostname`".

What's next ?? what did I miss??  
Thanks for any pointers you can give me.
-- 

-->BoB Miorelli, Pratt & Whitney Aircraft
philabs!pwa-b!miorelli
utah-cs!utah-gr!pwa-b!miorelli

lrr@princeton.UUCP (Larry Rogers) (11/07/85)

The DMR, being a point-to-point link, needs you to tell it the destination
address.  You do this by writing a program that translates the remote
host name to an internet name and then does the SIOCSIFDSTADDR ioctl on
the device.  A netstat, -i I believe, will then show that you have set that
address.  Typically, you need to set the destination address before you do
the ifconfig.  In the ifconfig, you need to also disable arp (-arp) and
trailers (-trailers) if you aren't using them.  Finally, the DMC driver
that comes with 4.2 is not as good as a more recent one from Bill Nesheim
from Cornell (bill@cornell.arpa).  Contact siemens!jcc for a copy of the
destination setting program and bill@cornell.arpa for a better driver.
Have faith - they do work.


Larry Rogers
Princeton University
Department of Computer Science
Engineering Quadrangle Building, Room C334
Princeton, NJ 08544

UUCP:	princeton!lrr
CSNET:	lrr%princeton@CSnet-relay
PHONE:	609 452 6483

matt@oddjob.UUCP (Matt Crawford) (11/07/85)

In article <183@pwa-b.UUCP> miorelli@pwa-b.UUCP (Bob Miorelli) writes:
>I need help setting up a Unix network using a pair of DMR's.

I am answering this not because I know how to do it, but because
next month I will have to know how.  I looked at thevaxif/if_dmc.c
code and it looks like it's no good.  dmcinit() installs a route
(via rtinit()) which has destination == gateway == address of
the dmc interface.  The only other point-to-point interface I
have to compare this with is Rick Adams' if_sl.c, which I have
been using for well over a year.  The initialization sequence
for that does not use /etc/ifconfig, but another program which
does first a SIOCSIFDSTADDR, then a SIOCSIFADDR, causing a route
to be installed with destination == other host, gateway == this
host. 

>    Now what?? I'm not sure what goes in the /etc/hosts
>file (including how to specify the lopback).  I did add a line
>to my rc.local of the form "/etc/ifconfig dmc0 `hostname`".

I think that if it can be made to work at all, it will be by
doing
		/bin/hostname this-host-name
		/etc/ifconfig dmc0 other-host-name

Yuck.  Ifconfig ought to take another argument for point-to-point
interfaces. The host table should look like:

	127.1		localhost loghost	# sendmail wants loghost
	125.1		this-host-name		# or whatever number
	125.2		other-host-name		# or whatever number

Make sure that the output of "netstat -i" shows the dmc0 before
the lo0.  Feedback is solicited.
_____________________________________________________
Matt		University	crawford@anl-mcs.arpa
Crawford	of Chicago	ihnp4!oddjob!matt