Nicolas Williams writes:
> In any case, it seems to me that if forwarding is enabled then routing
> should be enabled and vice-versa,
I strongly disagree with that.
Forwarding is the act of receiving packets on one interface and
transferring them to another interface. Routing is the process of
computing feasible routes and in this case, "enabling routing" means
turning on one or more dynamic routing protocols.
The two are not the same thing. You can certainly forward without
running a routing protocol -- you do so with static routes. You can
run routing protocols without forwarding -- hosts naturally do this
(many without realizing it, as there are common protocols that pretend
to be routing protocols, though that's perhaps a separate issue[1]).
Of course, I think everyone ought to run routing protocols all the
time, regardless of whether forwarding is enabled or not. Routing
protocols are how you learn the best way to transmit a given packet,
and having each IP node independently computing that information is
far more pleasing an answer than having "dumb" hosts depending on
"smart" routers to make the decisions for them.
But that last bit is just me. ;-}
> so the split into transient (right?)
> forwarding services and non-transient (right? what if only static
> routes are configured) routing services seems artificial.
If it's not "enabling routing protocols," how do you name the
distinction between running a dynamic protocol and using only static
routes?
[1] Among these "fake routing protocols," are DHCP, ICMP Redirect,
ICMP Router Discovery, and rpc.bootparams. There may well be
others, as folks seem to be _really_ fond of reinventing not-
entirely-round versions of this particular wheel. They share
among them the central fault that they don't deal very well with
dynamic updates, where real routing protocols do in fact deal well
with those issues.
--
James Carlson, KISS Network <james.d.carlson at sun.com>
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