Re: Patch for route.c
8 Apr 1997 18:34:45 +0200

"Richard B. Johnson" <> writes:
> This is _NOT_ nonsense! If you are running gated in the manner, you
> are contributing to LAN congestion by duplicating packets.

Gated is smart enough to realize that it should toss a route when it knows
a better one. (In that case, there are no duplicate packets.) _If_ it is
configured properly.

> A machine on __any__ single __physical__ network link needs only two routes.
> Note the emphasis on "any" and "physical".
> (1) A route to its local network or subnet.
> (2) A route to all other places.
Wrong. An Ethernet is a single physical network. If there's more than one
router on that network, and all the local machine knows is its default
route, _then_ there will be duplicate packets.

If by "single link" you mean "point-to-point link", then you're right, but
most people here don't assume that a priori.

> This is _NOT_ nonsense! Traceroute will see the routing that occurred
> in spite of the fact that another machine will take these same packets,
> duplicate them on the same wire, and send them to the same destination
> address. The destination address will then get the duplicate packets
> which it will throw away in the (overburdened) network code.

These are not broadcast packets. There _is_ no other machine that will also
see the packets. All of these packets go from one machine to one other
machine, and traceroute _will_ show every hop.

If you have inefficient routing, i.e. a -> b -> c where a and c are on the
same Ethernet, then you need to install a better route on a. There are only
two ways to do that, i.e. either run gated on a, b and c, or install the
necessary static routes on a.

Q: What is the difficulty with writing a PDP-8 program to emulate George Bush?
A: Figuring out what to do with the other 3K.
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