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| Problem with TCP keepalive |
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| PeterPotkay |
 Posted: Wed Jun 07, 2006 4:46 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7723
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| awatson72 wrote: |
If my assumptions are correct, (and I’ll try to do some more verifiication), the question of why a keepalive/heartbeat isn’t happening for the “companion” channel, is still outstanding. IMHO, this channel should be kept alive by heartbeat or keepalive, but even with a sniffer hooked to the server, I still see no traffic that would suggest these are flowing.
Thoughts? |
Because the "companion" channel is not servicing any MQGET with wait calls is the reason you see no HBs.
How Keep Alive notices the other side of any TCP/IP connection (MQ related or not) is live without sending data is a mystery to me. Unless the type of data used by Keep Alive is recognized by the Firewall as not good enough to qualify the connection as active. This is really a question for a Network / Firewall guru. Do share if you find out.
Another way is to make the companion channel active. Jeff says its an extra connection from the pool. Is there a way to configure the pool to be the same size as the # of live MDBs, so every connection is hosting polling MQGETs?
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Peter Potkay
Keep Calm and MQ On |
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| awatson72 |
| Posted: Fri Jun 09, 2006 10:30 am Post subject: |
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Acolyte
Joined: 14 Apr 2004
Posts: 69
Location: Freeport, Maine
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As a post-mortem to this matter, it turns out that in order to make MQ aware that you have changed the tcp_keepidle setting on the OS, you must restart the queue manager. So, the QM must be restarted not only to pick-up turning on keepalive in qm.ini, it also must be restarted to pick up changes to the OS tcp settings. Seems obvious in hindsight, but in our case, we had reduced the keepalive from the default of 2 hours to a much lower value of 20 seconds. Everything I read said that this takes effect for any new connections, so I stopped the app and the SVRCONN channel, and made sure the connections went away using netstat, and then restarted, but no changes. I even restarted inetd.
Anyway.
Everything seems simple in hindsight.
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Andrew Watson
L.L. Bean, Inc. |
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| PeterPotkay |
| Posted: Fri Jun 09, 2006 4:21 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7723
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so the Keep Alice setting at a lower value is sending something down the connection often enough so that the firewall doesn't kill the connection, even though there may be no MQ calls or no MQ HBs flowing for long periods of time?
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Peter Potkay
Keep Calm and MQ On |
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| awatson72 |
| Posted: Mon Jun 12, 2006 12:05 pm Post subject: |
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Acolyte
Joined: 14 Apr 2004
Posts: 69
Location: Freeport, Maine
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| Yes, the keepalive packets satisfy the firewall's criteria for an "active" connection. Thank goodness, wasn't sure where to turn next since the FW admins weren't budging on their configs! |
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