Having problems with limited broadcast

Bruce Walker bmw at wezel.com
Thu Jan 8 17:04:21 PST 2009


Bruce M. Simpson wrote:
>
> The folk who point out that link-local addresses could be used, have 
> an interesting suggestion which might work for you.

Peter, I understand your issue with the (apparent) restriction of the 
169.254/16 range, though I'd point out that the IPv4-LL addressing 
scheme is considered a fall-back plan by most systems implementors.  
Your systems could look  for DHCP first then failing that, drop back to 
IPv4-LL and get an address.  The picky customers would simply be 
required to supply a DHCP server.  Everyone else presumably doesn't care 
as long as the boxes can communicate.


But there's another useful point to pickup from the ZeroConf stuff.  I 
implemented a small standalone IPv4-LLA daemon using libevent, libnet 
and libpcap.  IPv4-LLA needs to muck around with a completely 
unaddressed interface (like you are doing with your DHCP-lite), sending 
and listening-for broadcast and directed ARP packets, per RFC 3927.  It 
was trivial to do this in a completely portable way using libpcap and 
libnet.  I'd highly recommend to you that you link those libraries into 
your Python DHCP-lite app and you will be able to deploy relatively 
painlessly on any platform that those libraries are ported to.

http://sourceforge.net/projects/pylibpcap/
http://pylibnet.sourceforge.net/

Cheers!

-bmw


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