Scott,
Thanks for the brief. Timestamping of only PTP packets is not
particularly interesting, so it may be that the '580 is the first
interesting chip for packet capture purposes. I'll have to do some
further reading though.
Darren
On 26/05/10 09:18 AM, Mcmillan, Scott A wrote:
Darren,
V
On Wed, May 26, 2010 at 9:03 AM, Mcmillan, Scott A
wrote:
> Guy,
>
> Both the 'raw' and 'nic' timestamps are in the form of seconds since the Unix
> epoch, plus fractions of a second. Please see my response to Darren for more
> info on the difference between these two timestamp sources.
>
> The
Guy Harris wrote:
Is there ever any reason *NOT* to use the hardware timestamp if it's available?
Only if it and the host time are not sufficiently in sync and you want to
correlate with other things timestamped with host time.
rick jones
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Darren,
Various flavors of timestamping are available on Intel NICs. For example, the
82576 can timestamp PTP packets in hw, but not general purpose packets. My
guess is that the 82575 behaves like the 82576 with respect to hw timestamping,
but I'm not sure. Please refer to the product docs.
Guy,
Both the 'raw' and 'nic' timestamps are in the form of seconds since the Unix
epoch, plus fractions of a second. Please see my response to Darren for more
info on the difference between these two timestamp sources.
The only reason I can think of to use 'raw' is for debugging.
Regarding
Darren,
Using hw timestamps is a two step process.
First, the SIOCSHWSTAMP ioctl instructs the NIC driver to turn on hw
timestamping. I assume that a tcpdump user will want to enable hw timestamping
for all packets, so I hardcoded hwconfig to HWTSTAMP_TX_ON and
HWTSTAMP_FILTER_ALL. Somethi
