From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: SL/IP and routing under Ultrix 4.2 on VaxStation 3100
Keywords: SL/IP Ultrix Routing Bridge
Organization: Weber State University  (Ogden, UT)
Date: Mon, 23 Nov 92 21:51:57 GMT

In article <1992Nov22.192130.1720@mjbtn.jobsoft.com> root@mjbtn.jobsoft.com (Mark J. Bailey [ADMIN]) writes:
>Hello,
>
>We are trying to figure out a problem and maybe some of you can help us.
>
>what we are trying to do is use SL/IP on a VaxStation 3100 running Ultrix
>4.2 to connect a 286-AT running an amateur radio tcp/ip software package
>called (KA9Q).  Getting the link up is no problem.  The 286-AT machine is
>then linked on the radio interface (ax0) to a wireless TCP/IP network around
>our region on the amateur radio bands.  The VaxStation is called 'turing'
>and its IP address is 161.45.1.14.  It is on a LAN of other Ultrix 4.2
>workstations connected via thinnet ethernet.  There are no subnets present.
>The entire ethernet is one network.  The 286-AT is called 'w4efq' and has
>an IP address of '161.45.63.4'.

[ ... ]

>What our problem is, is that we cannot seem to get other workstations
>on the ethernet to be able to access w4efq via the slip interface on turing
>*UNLESS* we specifically add a route to the workstation in particular
>that says
>route add 161.45.63.4 161.45.1.14 1
>ie, w4efq is via gateway turing.  Then it works great!?!?  w4efq has no 
>problem replying to say, 161.45.1.1, and 161.45.1.1 will reach w4efq as long as we manually add the route above.  what we want it to somehow have turing
>be "listening" for w4efq's address and say "ah, i know what to do with
>this one" and send it up the sl/ip line.  We don't want to have to go to 
>each and every workstation and add routes by hand.  likewise, it seems to
>me that one should not have to update every node in a network if you use
>sl/ip to "bridge" another network in (as in my case); attaching it to just
>one node in the main network (in my case, turing).  Maybe I am wrong.  :-)
>I know I am confused!  :-)

1)	a)	"OPTION GATEWAY" in your 3100's config file (don't know
		if Ultrix supports this) and rebuild the kernel to allow
		routing between subnets.
	-OR-
	b)	Get (and run) gated (from gatekeeper.dec.com, etc.).

2)	a)	Subnet your wires to give a netmask of 255.255.255.0 (or
		anything else you choose to get 161.45.63.x and 
		161.45.1.x off the same wire.

3)	a)	There is a default host doing the routing for 161.45.x.x;
		tell IT the route to 161.45.63.x is through 161.45.1.14.
		This will make the other hosts send packets to the
		"unknown" 63 wire to the default hosts, which will
		forward them to 161.45.1.14, which is your gateway to
		the 161.45.63.x subnet.

4)	a)	Default the routing for the NET 161.45.63.x to the slip
		link; this will avoid a routing loop which you might
		otherwise have if someone tries to talk to 161.45.63.9
		(or some other nonexistant host) on the 63 net; you
		don't want these packets going back to your default router
		for the 161.45.x.x wire.  Alternately, self designate as
		the 161.45.63.x router and specify a single host entry
		for the SL/IP.

Topologically:

	161.45.x.x ----+------------------------+-------------
	domain	       |			|
		       |			|
		    default		   161.45.1.x
		    domain		     subnet (OPTIONAL)
		    router		     router
						|
						|
	161.45.1.x -----+-----------------------+-----
	subnet		|
			|
		161.45.1.14 host /
		161.45.63.x gateway
			|
			|
	161.45.63.x ----+---------------+-----------------
	gated				|
	subnet			161.45.63.4
	(SINGLE ADDR)		SL/IP host

This basically works for us (with gated) using a MVAX II w/Ultrix.


					Terry Lambert
					terry@icarus.weber.edu
					terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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