serious packet routing issue causing ntpd high load?

Li, Qing qing.li at bluecoat.com
Thu Nov 3 14:05:09 UTC 2011


This endless route lookup miss message problem is reproducible without FLOWTABLE. 
The problem is with the multiple FIBs. I cannot reproduce this problem in my home network 
but the problem is easily seen at work.

The route lookup miss itself in multi-FIBs configuration may be normal depending on 
the actual system configuration. It's the flooding of RTM_MISS messages that is abnormal.
For example, if the route to the DNS servers is not configured in all FIBs, then the RTM_MISS 
message will be generated when an userland application sends to an explicit IP address
in a specific FIB.

In any case, I can reproduce the issue consistently and just trying to get a few uninterrupted 
hours to get it done.

--Qing

________________________________________
From: Alexander V. Chernikov [melifaro at FreeBSD.org]
Sent: Thursday, November 03, 2011 6:43 AM
To: Steven Hartland
Cc: Li, Qing; freebsd-stable at FreeBSD.org; liv3d at multiplay.co.uk
Subject: Re: serious packet routing issue causing ntpd high load?

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On 10.10.2011 13:50, Steven Hartland wrote:
> ----- Original Message ----- From: "Li, Qing" <qing.li at bluecoat.com>
>
>>> RTM_MISS: Lookup failed on this address: len 184, pid: 0, seq 0, errno
>>> 0, flags:<DONE>
>>> locks:  inits:
>>> sockaddrs: <DST>
>>>  ::A.B.C.D
>>>
I'm unable to reproduce an issue on (nearly) GENERIC 8-S, but I see
nearly the same situation on 8.1-S box with FLOWTABLE enabled.

Do you have FLOWTABLE option in your kernel config ?
>>
>> Would it be possible for you to email me what exactly does "::A.B.C.D"
>> map into WRT your system or infrastructure ?
>
> Sorry for the slow reply been out of the country.
>
> All the hosts are local machines same /24 connecting to the server for
> mysql. It seems to be that every packet either to or from for the mysql
> server is generating an RTM_MISS.
>
>> And are you able to share your "ifconfig -a" and "netstat -rn" output
>> with me privately ?
>
> On its way.
>
>    Regards
>    Steve
>
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- --
WBR, Alexander
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