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From: Jeff@soma.bcm.tmc.edu
Newsgroups: comp.sys.masscomp
Subject: Re: ethernet bridge on masscomp
Message-ID: <3267@soma.bcm.tmc.edu>
Date: Mon, 23-Nov-87 18:08:49 EST
Article-I.D.: soma.3267
Posted: Mon Nov 23 18:08:49 1987
Date-Received: Mon, 30-Nov-87 03:39:59 EST
Sender: masscomp@soma.bcm.tmc.edu
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Approved: masscomp@soma.bcm.tmc.edu
In-Reply-To: Your message of 20-Nov-1987 17:50-EST (Friday)

Qotd: A mind is a terrible thing.


> I have not actually used Dual Net but have had an extensive discussion
> with engineering about it.  The software package allows you to connect
> one machine to two different networks and access either network from
> that machine. *BUT* it does not provide any gatewaying capablities at
> all.  If you want to got from a machine on network A to a machine
> on network B you must first telnet/rlogin to the Dual Net machine
> and then telnet/rlogin to the second remote machine.  In the past there
> was good reason why you could not do this, the Excelan [23]01 boards
> have the TCP/IP code onboard and the kernel has no easy way to
> provide a gateway function, gatewaying is done at the lower IP layer which
> the boards do not provide easy access to.  

 Dual-Net is intended for redundancy (that is, 2 separate wires with
the same network/host numbers) NOT for 2 distinct networks. It is most
definitely NOT 2 network interfaces on the same host. (It is also a
custom product that costs extra money, which you don't need to spend)

> Since the last major
> release of the ethernet software (number escapes me) you could run
> the Excelan boards in "link-layer" mode meaning that all TCP and IP
> processing is done in-kernel.  The Kernel code is based on the
> 4.2bsd networking code and it supports gatewaying.  BUT Masscomp
> for philisophical reasons has disabled this ability and will
> not allow gatewaying even for the in-kernel version.  

Untrue, there is no such 'disabled' software. Simply do what you would
expect to do to turn on the second interface (either LANCE & 201 or (2)
201 interfaces) with /etc/ifconfig, and it works. It is necessary to do
a '# route add ...' command to enable the actual forwarding of packets.
Interfaces must be link-level interfaces (tieln or lnexos in the config
file rather than exos). At this time, we don't supply the 'routed'
daemon, which is helpful, but not absolutely necessary for
running/using a gateway. Now, the other problem is that there is no
price list item for ordering the second interface, though many PEP
customers actually already have it.

Jeff Carter