another bug: system time change

[Arnold Nipper]

On 09.04.2010 10:22 Wolfgang Hennerbichler wrote

> Hi Ondrejs, 
> 
> I think I found another bug. For some mysterious reason our system time jumped forward (more than 30.000 seconds) on one of our route-servers. I don't know why this happened, but I suspect a broken ntp server could have caused this. Nevetheless, this was reason enough for BIRD to drop the BGP peerings: 
> 
> You see the log-entries from the wtachdog, which is run every minute, all of a sudden the time jumps to 10:08 UTC, and BIRD brings down BGP sessions. Are the session hold timers dependent on the system time? 
> 
> Apr  9 01:33:01 rs2 /USR/SBIN/CRON[25129]: (root) CMD (/usr/local/sbin/watchdog.sh)
> Apr  9 01:34:01 rs2 /USR/SBIN/CRON[25136]: (root) CMD (/usr/local/sbin/watchdog.sh)
> Apr  9 01:35:01 rs2 /USR/SBIN/CRON[25143]: (root) CMD (/usr/local/sbin/watchdog.sh)
> Apr  9 10:08:28 rs2 bird: R8596x189: Error: Hold timer expired
> Apr  9 10:08:28 rs2 bird: R8596x189: BGP session closed
> Apr  9 10:08:28 rs2 bird: R8596x189: State changed to flush
> Apr  9 10:08:28 rs2 bird: R3330x113: Error: Hold timer expired
> Apr  9 10:08:28 rs2 bird: R3330x113: BGP session closed
> Apr  9 10:08:28 rs2 bird: R3330x113: State changed to flush
> Apr  9 10:08:28 rs2 bird: R1853x104: Error: Hold timer expired
> 

Is this really a BIRD bug? I guess it is expected behaviour to drop a
session if you _think_ you missed keepalives

The bug is w/ the underlying OS. Virtualisation and keeping time really
seems to be a problem. For this and other reasons we refrain from using
a VM for RS.



Arnold
-- 
Arnold Nipper / nIPper consulting, Sandhausen, Germany
email: arnold at nipper.de       phone: +49 6224 9259 299
mobile: +49 172 2650958         fax: +49 6224 9259 333

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