SUMMARY: How to add new class C addresses to existing network

From: Bill Hart (
Date: Thu Jun 17 1993 - 14:00:29 CDT

Many thanks to all who replied, my original query was -

> This is probably a dum question, but I can't find the answers
> anywhere in the documentation so ....
> We're rapidly running out of addresses on our class C network,
> and have just received a shiny new class C address. At the
> moment I'm setting up some SS 10/30's (Solaris 2.1, no NIS) to go
> onto a research ship and have put them onto the new class C
> address, on the same peice of wire as our existing machines.
> My problem is I can't figure out what to do to get them to
> talk to the rest of our machines (mainly Sun's running 4.1.3&NIS).
> I've added /etc/resolv.conf entries, but it looks as though
> the machines are expecting some sort of gateway which I don't
> have.
> So in brief, same peice of wire, two different class C addresses
> (192.67.12.X, 202.0.98.X) what do I have to do to get the
> machines to route packets to each other without a gateway or
> router ?

The replies were divided into two camps, those who said it
couldn't be done and you had to have a router of some description,
those who said it could be done (but it might be a bad idea).

For my purposes it's a purely temporary measure, while I wait for
some more routers etc (and while the new shipboard system is
being developed).

The most succinct answer was
> From Wed Jun 16 06:41:40 1993
> add a route on each machine that "points" to the other class C
> network. use a metric of 0 to indicate that the other net
> is directly connected:
> route add `hostname` 0 # for the 192.67.12 hosts)
> route add `hostname` 0 # for the 202 hosts)
> each machine should be its own gateway, since it should send
> packets out its own ethernet interface.
Which works fine (on Solaris 2.1 you have to change hostname to uname -n).

Also an alternative method using an undocumented (?) file /etc/gateways
> From Thu Jun 17 03:07:40 1993
> Alternatively, /etc/gateways would have something like:
> net gateway aaa.bbb.ccc.ddd metric 0 passive
> My personal preference is to go with the /etc/gateways file setup.
> in.routed will then add the route for you when it starts up. You can
> check by doing netstat -r, it should show the new route setup. You
> don't need to do anything else to the rest of your machines as the
> routing info will be broadcast around the net and they'll pick it up.
> Just check with netstat -r that they see the route to the other net
> through the routing machine.
> Oh yeah, if there's to be a reasonable amount of traffic between the
> two nets use a reasonably fast machine as the router, an SS2 or SS10 or
> SS690 would be ok. Avoid 4/490's or anything with the ie0 interface as
> they're not as fast.
Which I haven't tried as yet as I'm quite keen to restrict access to
these machines until I know more about Solaris 2.x and it's setup.

Thanks again to

Bill Hart Internet :
Network Manager Phone : +61 02 206 442
CSIRO Division of Oceanography Fax : +61 02 240 530
Hobart, Tas., 7000 Australia Paging: +61 08 001 234 (quote #29474)

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