[Spread-users] spread on FREEBSD

John Schultz jschultz at commedia.cnds.jhu.edu
Sat Oct 25 13:33:34 EDT 2003

Just to follow up on Ryan's email, 

You can choose any of the available multicast addresses that you like for
your segment multicast address; just pick one (for example, you could use  As long as all the machines in a given Spread segment
are connected by hubs/switches/routers that forward their multicast
traffic correctly it will work.

Broadcast addresses tend to have less issues with hardware supporting
them, so if multicast doesn't seem to be working, then try broadcast.  If
you have a class C network (i.e. your netmask is then you
your broadcast address is a.b.c.255.  If you have a smaller network (e.g.
slash 28), then your broadcast address should be a.b.c.d, where d is the
bitwise (1's) complement of your netmask's last byte (e.g. 255 is the
complement of 0: 255 == ~0 for a byte).

The error you are getting is most likely due to you specifying an illegal
broadcast address.  Your network is probably smaller than a class C
network, so when you try to open the broadcast port of a.b.c.255 it's
probably the wrong address for your subnet: again the last byte of your
broadcast addr should be the bitwise (1's) complement of the last byte of
your netmask -- check ifconfig -a to see what your netmask should be.

> I apologise for the length and ignorance of this email I hope someone can
> advise.

No worries, did you check out the Spread User's Manual on www.spread.org? 
It should have a lot of this kind of info in it.

John Schultz
Co-Founder, Lead Engineer
D-Fusion, Inc. (http://www.d-fusion.net)
Phn: 443 838 2200

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