[Spread-users] Clarification on spread configuration file

John Lane Schultz jschultz at spreadconcepts.com
Wed Oct 18 16:52:50 EDT 2006

Hi Matt,

The point of a Spread segment is to inform Spread which, if any, daemons can 
communicate with one another using hardware based 1-hop broadcast or multicast. 
  If you have many daemons that can communicate this way, then data 
dissemination between them can be much more efficient because a message can be 
broadcast once within a segment and all the daemons in that segment will get 
that message.

A configuration with multiple segments is (usually) a configuration with daemons 
from multiple local area networks.  There is no broad/multicast between these 
different networks so communications that must traverse the network boundaries 
have to use something like point to point UDP.

A Spread_Segment address should either be the broadcast address for the network 
in which the daemons of that segment reside or it should be a multicast address. 
        Be careful if you use private networks -- all the daemons within a 
configuration must be able to communicate with one another using point to point UDP.

Good luck,

Matt Garman wrote:
> I'm probably missing something obvious here, but I don't quite
> understand the Spread_Segment configuration directive.
> For example, if I have segments 1 and 2, with machines A and B listed
> under each segment respectively (i.e. A under 1 and B under 2), I can
> still "see" spread daemon A when running a spread app on machine B.
> So what's the point of having multiple Spread_Segments?
> Also, what exactly does it mean to list machines within the
> Spread_Segment stanza?  I.e., are you listing all machines to which
> spread should broadcast messages, or machines that are allowed to talk
> to the spread daemon or ???
> Finally, what are the implications of declaring a stanza like this:
>    Spread_Segment { ... }
> versus this:
>    Spread_Segment { ... }
> ?
> I'm just trying to make sure I set this up correctly!
> Thank you,
> Matt
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John Schultz
Spread Concepts LLC
Phn: 443 838 2200
Fax: 301 560 8875

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