Ethernet Gateway Problem on 3/260

[Bob Robison]

I am having a problem that I have been unable to resolve for a while, and
I'm hoping someone in netland can show me the obvious fix.  We have a
3/260 with two ethernet boards.  One board(ie0) is connected via thinnet
to a diskless 3/60.  The other board(ie1) is connected to various other
computers.  The 3/260 can talk to anyone on either net, but the 3/60 can
only talk to the 3/260.  It can however ping both ie0 and ie1 on the
3/260.  I am using subnetting, and netmasks are set 0xffffff00 everywhere.
On 3/260 ie0 is 129.162.161.11 and ie1 is 129.162.160.4, while the 3/60 is
129.162.161.10.  

Apparently the 3/260 is not properly acting as a gateway -- i.e.  packets
from the 3/60 that are intended to go beyond the 3/260 never get there.  I
have tried flushing the routing table and setting only the default (from
the 3/60 the default gateway is the 3/260,  from the 3/260 it is another
gateway hung off of ie1).

What am I missing?????  Please e-mail any words of wisdom to the address
below.  

Bob Robison	- Southwest Research Institute, Electromagnetics Div.
robison at dfsun1.electro.swri.edu
{sun!texsun, gatech!petro, cs.utexas.edu}!swrinde!dfsun1!robison