Re: Subnets and portmasters
Colin Pinkham (colin@iafrica.com)
Fri, 20 Oct 1995 12:24:17 +0000
> >There appears to be a lot of confusion over PortMasters and netmasks,
> >but there's one simple rule that should make it easier to understand:
> >All our products support ONE netmask per network. We expect a network
> >to be sliced up the same way, which is another way of saying that we
> >don't do variable length subnet masks. We will do VLSM in the future
> >(its one of the Big Four Requests).
>
> As an ISP, I always break my class C blocks using the same netmask, not
> enough hardware supports VLSM. The bigger problem is colapsing the
> subnet/netmask back into the .0 network for RIP broadcasts, i.e.
> 204.178.201.64 (255.255.255.224) will broadcast a route for 204.178.201.0 to
> the portmaster.
> If a connecting network broadcast an appropriate RIP route, all works fine,
> but if the connecting network does not or can not broadcast RIP (such as
> windows NT), then the route fails. This also causes problems if I want
> subnets to go to different portmasters.
>
> The only current way to route traffic to an NT (or other non RIP) gateway is
> by entering a route for each host on the destinantion network in the
> portmaster.
>
Or fool them. The following works for the Portmasters. On our gateway
Cisco router, we do the following.
ip route x.x.x.8 255.255.255.248 x.x.x.8
With the netmask entry on the portmaster, things work quite nicely.
The portmaster announces host routes, the cisco converts them to
subnet routes.Ugly as the Cisco may complain about recursive routing,
but it works.
Colin