Routing problems (fwd)

MegaZone (megazone@livingston.com)
Mon, 17 Jun 1996 13:49:10 -0700 (PDT)

Once upon a time John W. Temples shaped the electrons to say...
>past the PM they're connected to. With routing on, things seem to work
>ok, but my Cisco sees something I don't understand:
>
>R a.b.d.0 [120/1] via a.b.c.5, 00:00:16, Ethernet0
> [120/1] via a.b.c.1, 00:00:03, Ethernet0

This is what should happen - you are doing someting illegal, namely
non-contiguous subnets. RIP is puking all over it as I expect it to do.

>This is with two static users connected, one on PM1, one on PM5. I
>don't understand why the PMs choose to generate a network route for
>these users instead of a host route, while they're generating host
>routes for the dynamic IP users that should have network routes.

This is how we are *supposed* to be doing it - you are supposed to collapse
host routes to network routes on a network boundary. See the RFC on RIPv1.
So you have static routes from on network coming into a PM on another
network - the boundary is the ether0 of the PM, so we collapse and advertise
the entire network *as we should*. Since you have the same network connecting
to *two* PMs - violating the rule about contiguous subnets - both of them
are doing it. So they are fighting over owner ship of the full network. This
is all expected behavior by the rules.

>How can I convince the PMs to generate host routes for my static IP
>users, and network routes for my dynamic IP users?

You can't, you can't force us to do the wrong thing - except one small way.

What you need to do is use the netmask table to trick RIP. Set the netmasks
and we will start advertising a host route for just the first IP of the subnet
on the PM. Only other Livingstons with the same netmask set will
understand what this means, so set a static route in the Cisco aimed at one
PM. That PM will then know who really gets it.

-MZ

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