[Spread-users] Spread broadcast spam?

John Lane Schultz jschultz at spreadconcepts.com
Mon Jun 18 15:21:04 EDT 2007

Jan Mulders wrote:
> Why is Spread spamming the entire subnet?

Because you have configured Spread to spam the entire subnet.

The address immediately following 'Spread_Segment' is the address used to 
disseminate data packets to all the daemons listed within that same segment.  If 
you do not have multicast or broadcast enabled, then all of your daemons should 
be listed out in singleton segments.

> Why doesn't it list 'b retrans' as a number more than 0 in spmonitor? 

b-retrans indicates that the daemon had to do a system wide retransmission to 
recover lost packets for other daemons.  In your system it doesn't look like it 
ever needed to do that to recover packets.

> Why doesn't Spread notice that Multicast and Broadcast don't work, and 
> fall back to Unicast on a per-session rather than (presumably) 
> per-packet basis?

Looking at your spmonitor output fdc33 is overcoming being configured with a 
broken broadcast address as it is unicast retransmitting pretty much every 
packet (probably to fdc2 to whom it is configured to communicate using broadcast).

Spread isn't currently designed to overcome byzantine behavior from its 

> Is there an option to change this behaviour?

Yes, configure Spread the way you want it.  Since it seems you don't want 
multicast or broadcast between any of the daemons I would recommend trying 
something like this:

	fdc2	xx.yy.zz.108

	fdc33	xx.yy.zz.175

	fdc27	aa.bb.cc.241

That should cause all of your daemons to use point-to-point UDP traffic to 
disseminate data traffic to the other daemons.

 > fdc33 is sending the logs, and fdc2 is recieving the logs.

Please be aware that even though only one machine is sending and another 
receiving that all data traffic is disseminated to all daemons whether they are 
involved in the particular group level communication in question or not.


John Schultz
Spread Concepts LLC
Phn: 443 838 2200
Fax: 301 560 8875

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