[openbeosnetteam] Re: Network stack question

  • From: "Hugo Santos" <hugosantos@xxxxxxxxx>
  • To: openbeosnetteam@xxxxxxxxxxxxx
  • Date: Wed, 27 Jun 2007 14:15:52 +0100

On 6/27/07, Ivo Vachkov <ivo@xxxxxxxxxxx> wrote:
Hmm, I'd say ICMP sits beside IP. It controls IP and TCP/UDP at the
same time.

 Hm. :-)

Where do you plan to define these messages (I mean where would you
want to implement them) ? At TCP/UDP ? I think it is most logical to
implement that kind of messages at ICMP and call whenever we need one
from other layers (TCP/UDP/IP).

 Now i understand your original question. Unfortunately this approach
is not reasonable as it violates layer boundaries. In my view, there
should exist a set of known error message codes, a set that makes
sense from an ICMP point of view, that are propagated down the stack.
Only the IP module should be aware of ICMP. This also allows IPv6 and
ICMPv6 to be plugged nicely into the stack without modifications to

 -> IP
   -> UDP
     -> No endpoint found, return "Port not reachable"
 -> IP sends ICMP Port not reachable.

 Axel may have a different view on this.


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