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Re: Re: SNMP lockup


Sergei Gavrikov wrote:
> On Fri, May 08, 2009 at 10:38:24PM +0000, Grant Edwards wrote:
>> On 2009-05-08, Sergei Gavrikov <sergei.gavrikov@gmail.com> wrote:
>>
>>> If your guess is right...
>> It's not a guess.
>>
>> The problem occurs when cyg_snmp_get_if() is called with if_num <= 0.
>>
>> The loop takes 1-2 minutes to loop from -1, -2, back to 0,
>> causing the SNMP management thread to lock out all lower
>> priority threads while it's doing so.
> 
> Then fix it.
> 
>>> Can you walk here with/without tweaks when if_num=0
>>>
>>> repo/devo/ecos/packages/net/snmp/agent/current/src/mibgroup/mibII/interfaces.c:398
>  
> [snip]
> 
>> I'm surprised nobody else has run into this.  I'm told all our
>> customers who have HP or Cisco SNMP managers have had to
>> disable SNMP support in our products to keep them from locking
>> up every few minutes.
> 
> I was just googling +'ifPhysAddress.0'
> 
> It seems you are not alone :-)
> 
> http://mtsc.moxa.com:8888/Software/DN/NPort/Firmware/NPort%205000/NPort%205600/ver3.2/VERSION.TXT
> 
> <quote>
> ver3.1 (2006/05/16)
> 
> 3. Fixed the problem that querying NPort by SNMP Software would cause NPort stop replying ethernet packet
> 
>    while querying "GET iso.3.6.1.2.1.2.2.1.6.0", which is resolved as
> 
>    "GET iso.org.dod.internet.mgmt.mib-2.interface.ifTable.ifEntry.ifPhysAddress.0".
> </quote>
> 
> 
> UCD-SNMP had a lot of holes. eCos UCD-SNMP implementation has even more
> holes :-(

Feel free to improve this - much of the networking code,
including SNMP, is more than seven (7!) years old.  A lot
has gone on in the world in that time...

-- 
------------------------------------------------------------
Gary Thomas                 |  Consulting for the
MLB Associates              |    Embedded world
------------------------------------------------------------

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