[ECOS] IP limited broadcasts problems

[Andrew Lunn]

On Sat, May 19, 2001 at 06:54:41PM +0200, Robin Farine wrote:
> It seems to me that the OpenBSD IP stack does not handle correctly
> IP limited broadcasts. Take a host with N Ethernet interfaces, each
> with an IP address on a separate IP subnet and with the flag
> IFF_BROADCAST set. The host sends an IP limited broadcast. I would
> expect that an Ethernet broadcast goes out of each interface
> (provided that a route to the interface's specific IP subnet exists
> for each interface).

> Did someone already observed & reported this problem or should I
> rather go to sleep, and then read TCP/IP Illustrated again?

Good morning Robin, Hope you slept well.

I just checked the Internet STD documents to see if this is broken
according to the standards. Best i could find was, in std3,
"Requirements for Internet Hosts" 

              There has been discussion on whether a datagram addressed
              to the Limited Broadcast address ought to be sent from all
              the interfaces of a multihomed host.  This specification
              takes no stand on the issue.

So it seems this falls into one of those gray areas. 

You probably want to swap mailing lists and post to an OpenBSD
list. It may also be worth looking at an OpenBSD application that uses
Limited broadcasts. rwhod should be a simple example, or DHCP server
for something more complex.

        Andrew