[comp.protocols.tcp-ip] adversity or perversity

JOHNSON@NUHUB.ACS.NORTHEASTERN.EDU ("I am only an egg.") (07/28/87)

     Hi!

     I have a problem and I'm not sure I believe what I see.

     I have an ethernet with disparate tcp's around on it.  We have bsd 
4.3, Symbolics, Sun release 3.2, Micom np100 board running tcp among
others.  I'm in the middle of changing network numbers.  Now, networks
on the same ethernet won't talk to each other.  It seems as if IP wants
to have one network number per ethernet.  I really don't see why this
should be so. 

     Is this the way of IP?  Does it really want one network number per
ethernet?  Is there an RFC that says this should be so?  If so then 
which one so I can go look?  If it isn't IP is it the the perversity of 
ethernet interface manufacturers?

USnail:
          Chris Johnson
          Academic Computer Services
          Northeastern University 39RI
          360 Huntington Ave.
          Boston, MA. U.S.A. 02115
AT&T:     (617) 437-2335
CSNET:    johnson@nuhub.acs.northeastern.edu
ARPANET:  johnson%nuhub.acs.northeastern.edu@relay.cs.net
BITNET:   johnson%nuhub.acs.northeastern.edu@csnet-relay

(Always vote.  There may not be anything you want to vote for, but
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Mills@UDEL.EDU (07/31/87)

Chris,

You are asking for a lot. In conventional wisdom multi-network Ethernets
are considered somewhat unstable and, so far as I know, are unsupported
by current host and gateway vendors. Some experimentation has been done
in the NSFNET community with these things, but the gadgets with which this
has been done (fuzzballs) are probably best left in their original cages.

See RFC1009 for further discussion on this point.

Dave

mar@ATHENA.MIT.EDU (08/02/87)

Multiple network numbers on a single wire can work if you are careful.
Proteon gateways will support this, as will 4.3BSD acting as a
gateway.  What you really have to watch out for are broadcast packets.
But if you don't run the rwhod or routed, it is unlikely that there
will be any IP broadcasts on your net.
					-Mark