[Spread-users] about spread multicast the message

John Schultz jschultz at spreadconcepts.com
Sun Mar 11 12:31:18 EDT 2012

The daemons are not forming a membership together for some reason.

It could be that you have asymmetric communication in your network where m2's traffic can get to m1 but not m1's traffic doesn't get to m2.  That could be caused by firewalls or misconfiguration of multicast in your network.

Alternatively, their configuration files may be different, although it is not apparent from your email's text, such that they compute different configuration hashes and, therefore, refuse to acknowledge each other's existence.  Try using the exact same configuration file (i.e. - copy it from one host to the other) for both daemons.

When you start the two daemons, if things are working properly, then after a short while they should print out that they've formed a membership with one another.  If they don't and instead print out singleton memberships, then the likely culprit is one of the above issues.


John Lane Schultz
Spread Concepts LLC
Phn: 301 830 8100
Cell: 443 838 2200

On Mar 11, 2012, at 8:34 AM, xuansheng mo wrote:

 I use the tcpdump in m1: tcpdump -i en1 -n 'dst', when spuser in m2 join/leave or send message, the m1 can receive the package: > UDP, length 133
But spuser in m1 could not receive the msg from same group in m2.

2012/3/11 xuansheng mo <moxuansheng at gmail.com>
hello all:
I installed the spread toolkit in my OS, and config the spread.conf to run under multicast type.

The segment is below(m1 is my localhost)

Spread_Segment {

when the daemon run, I use the supser to test it.

spuser -s 3333 -u user1  | j spread1  | j spread2

spuser -s 3333 -u user2  | j spread  | j spread1

spuser -s 3333 -u user3 | j spread1 | j spread

and user1 send the message to group 'spread1', the user3 can receive the message.

All it works well in localhost.

But I start spread daemon on  host m2.

The segment is below(m2 is my localhost)

Spread_Segment {

First I connect the m1 to test.

spuser -s 3333 at -u user4 | j spread1 | j spread2

and the user4 can receive the message from user1.

but , the spuser -s 3333 -u user4 | j spread1 | j spread2 just connect the m2 locally.

And user4 could not receive the message from m1 with same group.

(It seems the two daemon couldn't exchange message each other, From the architecture about spread, 

it show in http://www.cnds.jhu.edu/pub/papers/cnds-2004-1.pdf, Each daemon keeps track of processes residing on its machine and participating in group communication).

So, Does my config file is right ? Or something wrong with it?

Thanks in advance.

Mo xuansheng


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