[Spread-users] UDP broadcast question

Monte Ohrt monte at ispi.net
Wed Apr 16 19:01:31 EDT 2003

On Wed, 2003-04-16 at 17:48, Jonathan Stanton wrote:
> On Tue, Apr 15, 2003 at 03:29:39PM -0500, Monte Ohrt wrote:
> > Hello,
> > 
> > We use currently use spread (v. 3.16.02) and mod_log_spread and
> > spreadlogd to send apache logs from a web cluster to a log server. Our
> > spread.conf file looks like this:
> > 
> > Spread_Segment {
> > 
> > server1
> > server2
> > server3
> > (etc)
> > 
> > }
> Is your network mask really a class B (/16) network space? Using a
> broadcast address of is sending the packets to all of the
> machines in the 10.131.*.* address space which is probably not what you
> want :-)

The network mask is a class B. We currently have 10.131.131.* and
10.131.200.* in the web server group, and could possibly get more. We
assigned a class B to this network segment.

> If your networks broadcast address is actually then
> changing to that will help some. You can also switch to using a
> Multicast address as long as all the machines using spread are on the
> same lan segment and your OS supports IP-multicast (most modern ones
> do).
> If you switch to multicast, replace the with 225.131.x.y
> (you can pick almost any network address between and
>, but some of the 224.* ones are reserved). Then the
> traffic will be filtered to only those machines who are part of the
> spread configuration.

So it sounds like the packets still need to be broadcasted to every
system in the group then, so the best way to isolate them would be with
a VLAN since I have desparate class C's being used.

> > 
> > 
> > I notice by all the blinking lights on the switch that the packets are
> > being broadcast across the entire network segment. We only have one
> > server ( doing the chore of listening and logging the
> > spread messages with spreadlogd. Is it possible to have the packets
> Is this machine running a daemon? I don't think so since it's ip address
> is not in the config file. If it is just a client connecting to adaemon
> on another machine, then the config file doesn't affect it at all. 

It is in the segment, I just didn't list them all out.

> > directed to that machine only (still via UDP) instead of broadcasted? If
> > so, how do I accomplish this? I thought about changing the configuration
> > to this:
> No. This won't work. The segment address does need to be a broadcast or
> multicast address so all the servers can communicate on it, even if you
> only have one "listener"

Thanks for the help!

> Cheers,
> Jonathan
Monte Ohrt <monte at ispi.net>

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