[Spread-users] Problem with segement in spread

Akezyt Janedittakarn ajanedit at andrew.cmu.edu
Sun Nov 16 02:26:34 EST 2003



I am a graduate student at Carnegie Mellon University using spread for my
Master's thesis project on fault-tolerance for distributed wireless systems.


I have a couple of questions about the use of segments in spread. I was
hoping that I could get answers from you.


1) The first question is "does segmentation in spread provides message
(traffic) isolation between segments?" For example, if there are two
segments, Seg1 and Seg2, and there is one group, G1. If a node on Seg1 sends
a message to G1 and there are no members of G1 in Seg2, should I see that
message at the nodes in Seg2? From spread's documentation and papers, that
should not be the case. However, in my following settings, I still see that
traffic on Seg2. The configuration file is.










The steps that I took are as follows:

- I ran spread daemon on only S1 and S2.

- Next I ran a server program on S1 which creates/joins a 'servers' group.

- I ran a client program on S2 sending messages to 'servers' group.

- No spread daemons are running on S4

- Then I used 'ethereal' to capture the traffic at S4. It got around 16
frames per S2's request (all of them are broadcast messages). This is fine.

- Next I ran spread daemon on S4. I captured traffic at S4 again, this time
I got I got around 400 frames per S2 request. Most of the frames are unicast
message directly sent to S4 from S2 and unicast message from S4 to S1. It
seemed like they formed a ring which is contradict to its documentation
because it is across segment.


2) Is it necessary to have 2 segments in 2 separate subnets?

Currently, both segments are on the same Ethernet segment (connected to the
same hub). I am not sure that this should matter or not.


3) Is there any flag or configuration option that I can use to make spread
suppress those unnecessary messages?


I have been stuck on this problem for a while now, and would really
appreciate any answers and advice.


Thank you,



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