Summary (sort of): static route problem

From: Marc Cohen (
Date: Thu Jan 18 1990 - 07:29:21 CST

Thanks to all who responded to my query.

You all said that the prudent thing to do was to use the same netmask
( on both sides of the gateways and subnet all of the machines
on the engineering 'backbone' this way too. Well this does work, but it just
won't do.

The remainder of our network here is 'flat'. That is to say, there is no
gateway between our 128.119.91 'net' and, for instance, the 128.119.41 'net'
or our gateway to the outside ( If We use a Class C subnet mask
we will be able to see the machines behind the similarly subnetted gateways
but not several hundred other (more important) machines.

Also, at the risk of sounding obstinate, SunOS 4.0.X was supposed to support
different masks on a gateway (unlike 3.5 where they HAD to be the same). We
also choose not to use 'routed' because of the traffic and because previously
the only route any machine needed was a default route to our
gateway to the outside. Another problem with using a Class C netmask is that
there are many other machine that do not understand subnetting at all.

I think the solution is to do what we were doing but educate our off-campus
gateway about these subnets so that, once again, we will only need a single
default route.

I have enclosed my original posting below and thanks again to all who
responded. If anyone has any other ideas, I'm still willing to listen.


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We have a class B network and are using 128.119.91 as the Engineering network.
We have three subnets gatewayed to this network with 2 sun 3's and a microvax.
The gateways are all configured like this:

sim1# ifconfig ie0
        inet netmask ffffff00 broadcast
sim1# ifconfig ie1
        inet netmask ffff0000 broadcast

Machines on the 128.119.91 network are configured like this:

gumby{49}% ifconfig ie0
        inet netmask ffff0000 broadcast

and have static routes that look like this in rc.local.

/usr/etc/route add mag-net mag-gw 1
/usr/etc/route add sim-net sim1-gw 1 #sim-net=128.119.87, sim1-gw=
/usr/etc/route add pclab-net pclab-gw 1

The problem is that machines on the 128.119.91 network can only connect to the
subnet that is listed first when you do a netstat -r. Has anyone ever seen this
behavior before?

Thanks, Marc

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