[Spread-users] UDP broadcast question

[Jonathan Stanton]

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  10.131.255.255:4803 {
> 
> server1 10.131.192.1
> server2 10.131.192.2
> server3 10.131.192.3
> (etc)
> 
> }

Is your network mask really a class B (/16) network space? Using a
broadcast address of 10.131.255.255 is sending the packets to all of the
machines in the 10.131.*.* address space which is probably not what you
want :-)

If your networks broadcast address is actually 10.131.192.255 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 10.131.255.255 with 225.131.x.y
(you can pick almost any network address between 224.0.0.0 and
239.255.255.255, 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.

> 
> 
> 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 (10.131.192.118) 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. 

> 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"

Cheers,

Jonathan

-- 
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Jonathan R. Stanton         jonathan at cs.jhu.edu
Dept. of Computer Science   
Johns Hopkins University    
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