Bizarre subnetwork non-visibility problem?

Bizarre subnetwork non-visibility problem?

Post by Van Snyd » Wed, 19 Jun 1996 04:00:00

I have HP 720 running HP-UX 9.05 attached to a subnet (A).  Also on subnet A
are numerous other computers, including some other Unix, some Macintosh, at
least 3 PC's with OS/2 and TCP/IP for OS/2 v.2.0, and some printers.

From home, I connect to a modem on HP 720.  I start as a dumb terminal, and then
I use slip (HP calls it ppl).  Then, I log in, typically to HP 720 using telnet.
When I first set this up, the routing didn't work:  All I could see upon
logging into HP 720 via modem/slip/telnet was subnet A, until somebody told me
to publish the IP number of the slip connection, as being associated to the
wired-in address of the network interface on HP 720, using "arp".  Now, the
slip connection can see everything, _except_ that anything on subnet A other
than HP 720 is invisible -- not even "ping" works (nslookup has no trouble
telling me the IP numbers, and "ping" with IP numbers instead of names doesn't
work, either.)  Furthermore, once slip is running, directly from home I can
only log into HP 720 or systems _not_ on subnet A via telnet, ftp, www, ...,
and not even "ping" can contact anything on subnet A, except HP720, from home.

BUT, If I log in by modem to HP 720, thence from HP 720 on subnet A to a
machine on subnet B via telnet, then everything on subnet A is _visible_.  But
If I then log into a machine on subnet A via telnet (say, one of the PC's
using OS/2), different from HP 720, the rest of subnet A is still _invisible_.
Summary, once slip is running:

  directly from home: subnet A is invisible
  home telnet HP 720: subnet A is invisible
  home telnet HP 720 telnet subnet B: subnet A is visible
  home telnet HP 720 telnet subnet B telnet subnet A:
    rest of subnet A, including HP 720 and "home," is invisible.

When I sit at the console either of HP 720 or one of the PC's on subnet A
that runs OS/2, or one of the Macintoshes, all of subnet A is visible, and so
is the rest of the world (but slip isn't running at that time).

I _think_ I've logged into HP 720 via modem, and just used a vt220 emulator
(instead of switching to slip), after I setup the "arp" subterfuge, and could
still see both subnet A and the rest of the world.  But I'll repeat this
experiment if anybody thinks it might be informative.

So the problem seems to be caused by a * of logging in via a slip
connection and the hand-waving using the "arp" subterfuge.

Do you have any ideas how to make subnet A, and all the rest of the world,
visible when I log in to HP 720 via slip?
What fraction of Americans believe   |  Van Snyder


1. Peer Setup, Multiple MS Networking Domains & Multiple Subnetworks


I am working with a PC running Warp Connect.  We recently moved this PC
from one
building to another.  The two buildings are on separate LAN segments and
the routers
will not pass NetBeui messages between the LAN segments.  Further
complicating the
move is the fact that we have multiple MS networking (LAN Server?)
domains that do
not fully trust each other.  The domain I need to log into is on a
different LAN
segment, but the login fails because the system cannot see this domain.
The only
domain that it can see is located on the same LAN segment.  I can login
to this
domain, but a NET VIEW command of the other domain fails.

I have configured MPTS for TCP/IP and "Netbios over TCP/IP".

Most of the systems here use Windows 95 or NT.  These systems have full
accross the routers, so I know that it can be done.

Any suggestions? Is it possible to configure my system to see accross
the routers?
What do I need in my configuration to do this?

I have limited OS/2 expertise.

If possible, please respond via Email as I do not regularly monitor this

Tony Bjerstedt
Keane, Inc

Opinions expressed herein are my own and may not represent those of my employer.

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