Mike Rosenlof napsal(a):
Hi,
I'm using corosync 1.4.1 on RHEL 6.2 I have a cluster of two nodes and we are passing node to node messages with the CPG message API (cpg_model_initialize, cpg_join, cpg_dispatch, etc...)
while the messaging is idle, if I run 'tcpdump' on the corosync source port 5404, we get three messages every couple of seconds::
14:47:41.384240 IP g5se-48521a.hpoms-dps-lstn > g5se-ad665b.netsupport: UDP, length 107
14:47:41.384693 IP g5se-ad665b.hpoms-dps-lstn > g5se-48521a.netsupport: UDP, length 107
14:47:41.593953 IP g5se-48521a.hpoms-dps-lstn > 239.192.42.210.netsupport: UDP, length 119
14:47:43.288532 IP g5se-48521a.hpoms-dps-lstn > g5se-ad665b.netsupport: UDP, length 107
14:47:43.289109 IP g5se-ad665b.hpoms-dps-lstn > g5se-48521a.netsupport: UDP, length 107
14:47:43.498385 IP g5se-48521a.hpoms-dps-lstn > 239.192.42.210.netsupport: UDP, length 119
etc...
Now when the node application sends a message to another node
stat=cpg_mcast_joined( commHandle.cpgHandle, CPG_TYPE_FIFO, &iov, 1 );
tcpdump captures a surprisingly large number of packets
14:47:45.525430 IP g5se-ad665b.hpoms-dps-lstn > g5se-48521a.netsupport: UDP, length 107
14:47:45.525576 IP g5se-48521a.hpoms-dps-lstn > g5se-ad665b.netsupport: UDP, length 107
14:47:45.526354 IP g5se-ad665b.hpoms-dps-lstn > g5se-48521a.netsupport: UDP, length 107
[snip, 59 length 107 messages deleted!]
14:47:45.540345 IP g5se-48521a.hpoms-dps-lstn > g5se-ad665b.netsupport: UDP, length 107
14:47:45.540603 IP g5se-ad665b.hpoms-dps-lstn > g5se-48521a.netsupport: UDP, length 107
Does anybody have an idea why there are so many messages for corosync to transmit a message of approximately 12 bytes?
thank you for any insight here...
corosync rotates token between nodes as a heartbeat (few in seconds) and
when messages are sent, token must rotate more quickly. Token itself is
quite small.
To see actual messages, filter mcast packets.
Does this answer your question?
Regards,
Honza
-mike
Mike Rosenlof
Sr. Designer, G5 Software
Louisville Colorado
80027 USA
www.genband.com<http://www.genband.com/>
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