time lag between /sbin/ifconfig eth2 up and when interface becomes usable...

Mikkel L. Ellertson mikkel at infinity-ltd.com
Fri Apr 11 18:17:50 UTC 2008


Bruno Wolff III wrote:
> On Thu, Apr 10, 2008 at 13:39:36 -0400,
>   Gautam Thaker <gthaker at atl.lmco.com> wrote:
>> From my tests it appears that it takes between 4 to 6 seconds after the 
>> "up" command before my UDP packets actually start going out. The tests 
>> are between two machines with addresses 192.168.0.2  <---> 192.168.0.3.
>>
>> Any hints welcome. The "/sbin/ifconfig eth2 up 192.168.0.2" command 
>> returns right away, but the interface is not ready to go for a few 
>> seconds. What can this be due to?
> 
> It might be waiting for a test to see if any other machine is using that IP
> address on that subnet. The time delay seems to be reasonable for a timeout
> to a whohas arp request. Looking at the network traffic should allow you
> to refute this or add some more suggestive evidence that this is the cause.
> 
Depending on the hardware, there may also be a delay while the 
hardware negotiates speed and duplex.

Mikkel
-- 

   Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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