SunOS & non-uniform subnet masks..
- To: email@example.com
- Subject: SunOS & non-uniform subnet masks..
- From: firstname.lastname@example.org (Andy Warner)
- Date: Mon, 2 Jan 1995 19:59:43 -0600 (CST)
Given the following (simplified) setup:
| SunOS | ethernet | NOS |---- 1200/9600 radio links
| 44.n.n.n |-----------------| 44.n.n.m | connected to 44.x.x.x
| Phone |
| Modem |
The Sun and the NOS box are on a small subnet of net-44, and the
default route for the Sun is set to be the NOS router.
This works just fine, until the modem is used to get a PPP connection
to the internet; then the default route becomes ppp0 (the PPP interface.)
It is not possible to set a route to 184.108.40.206/8 under SunOS, in fact
there is some quaint code that makes the assumption that within a
network, all subnet masks are identical. Since le0 has a subnet mask
and is part of the class A net-44, SunOS applies that netmask to the
route too, hence some miniscule part of net-44 remains accessible.
I realise that in theory, the internet-connected hosts on net-44
may remain available (subject to firewalls), but in reality any
open connections to 44.x.y.z go into deep-freeze.
I hear that BSD 4.4 has a more powerful routing subsystem (patricia
trees?) that propogates subnet masks, but short of re-writing in.c and
route.c, are there any other options ? At the moment, as soon as the
PPP link goes online, the SunOS box vanishes from the radio network
(which is a shame, since it is a mail-hub and DNS server.)
email@example.com Andy Warner, Cray Research, Inc. (612) 683-5835