Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!ucsd!ucbvax!OAC.UCLA.EDU!CSYSMAS
From: CSYSMAS@OAC.UCLA.EDU (Michael Stein)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  Using the 4.2 broadcast addr with 4.3 systems
Message-ID: <8909021836.AA24117@ucbvax.Berkeley.EDU>
Date: 2 Sep 89 16:25:00 GMT
Organization: The Internet
Lines: 48

>        On the topic of single IP address per host: I used to
> think so too, but I suspect it would result in routing chaos
> and poor choices in other ways.  Multi-connected hosts would
> likely suffer unnecessary outages or (just as bad) poor routing
> decisions (close hosts going the long way around) because of
> it.

Really?  I always thought it was the other way around.  Right now
my TCP connection is dead if my route fails to a milti-homed host
even if another route (to a different IP address) existed since
TCP connections are bound to an IP address pair, and NOT a host.
Isn't this an "unnecessary outage"?

> Hosts on the same network, but with different network
> addresses would suffer from different levels of service-- a
> nightmare to keep straight-- because distant gateways have
> incomplete or inconsistent information about the "different"
> networks.

That's a deficiency of the current routing implementations.
("it's a routing problem, not an addressing problem").

>        After all, the whole point of IP addresses is to make
> routing easy; if everything else works, humans shouldn't even
> have to deal with them...

It seems to me that the point of IP addresses is to avoid having
to place a route in each packet, instead only one value is needed
to indentify the target host.  Again note that TCP binds
connections to IP addresses (not hosts) and each UDP packet is
also bound that way.  Why should a PARITAL path failure cause the
data to be dropped?  I think that this whole area is just one
aspect of the general "IP routing problem".

>        Finally, directed broadcasts (again) break; suppose you
> have a network where every host on it is a gateway and each's
> IP address is taken from its other network. You have a network
> that is not addressable, so, though you could send packets to
> individual hosts, you could not broadcast to all of them with
> one packet, like you can now.

What about a multi-cast group address (or whatever it's called)?
Again since each one of those hosts is on multiple "networks"
I would assume that they are ALL involved in the routing protocols
on each of their connected networks (including comparing the
metrics of each) in making their routing decisions.

All we need is a complete routing protocol.....