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Re: Networking design proposal

From: Michal 'hramrach' Suchanek
Subject: Re: Networking design proposal
Date: Tue, 12 Nov 2002 15:43:19 +0100
User-agent: Mutt/1.4i

On Tue, Nov 12, 2002 at 01:12:08PM +0100, Niels M?ller wrote:
> Michal 'hramrach' Suchanek <hramrach_l@centrum.cz> writes:
> > On Wed, Nov 06, 2002 at 02:52:25PM +0100, Niels M?ller wrote:
> > > Olivier P?ningault <peningault@free.fr> writes:
> > > 
> > > > You didn't understand correctly. Layer 2 translator performs ethernet +
> > > > arp, not ip !
> > If you do not do IP int L2, how can you tell which L3 gets the packet? 
> The interface for reading raw ethernet frames should primarily filter
> on ethernet type code and ethernet addresses. If there are several
> processes (say, two completely independent ip-stacks) that want to use
> the same ethernet hardware and the same ethernet address, then the
> simplest way is to have the ethernet driver deliver each received
> frames to *both* processes.
I think you completely misunderstood my post as your comments seem to be
shifted by one layer. Or I misunderstood the pictures in prevois post.
> Or you can do something more clever with filters that look into packet
> contents (I've heard that some network cards even has some hardware
> support for that), but if you do that I think you want a nice general
> interface, and not code knowledge about the inside of ip packets into
> the ethernet driver.
Of course, reading frames from ethernet card = reading _all_ frames unless
the driver supplies some filter for whatever reason. One such filter is
non-promiscuous mode (the default :).
As I understansd the picture there is a layer L2 which has interface for
sending/receiving frames (possibly w/o the frame headers) on one end and
some ip interface on the other end.
The ip interface allows the L3 translators to register some ip:s.
I do not see any use for distinction between ip numbers and port numbers.
They were probably designed to have one ip on each interface(machine?).
Multiple ports used to address different applications/services. But that
is no longer true and you may want multiple ip:s on one interface or single
port with any ip etc. That makes the distinction between ip numbers and 
port numbers useless imho.

Michal Suchanek

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