[ARGUS] A concrete packet loss example :-)

[Peter Van Epp]

On Sat, Oct 16, 2004 at 10:48:15AM -0400, Kevin Miller wrote:
> > Input errors on both the gig
> >cards that are capturing on the link.
> 
> What kind of card are you capturing this data on?
> 
> -Kevin

	SysKonnect 9346(? some number like that) SX fibre, somewhat old. They
aren't the issue since with two machines and a crossover fibre netperf can
get ~950 megabits per second through them on the same hardware the sensor is
using (although come to think of it that was an older version of FreeBSD and 
therefore may be worth trying again) with a 9000 mtu.
	 A note for anyone else using them on taps, at least on FreeBSD you 
need to set them to manual fdx because they support and on a tap will default 
to hdx. My HPC folks haven't found such an option on the linux drivers, but they
also don't use taps usually. They do however have a gig card that my sniffer
shows is running hdx which they are chasing and another that when its host 
machine underuns sends a valid (i.e. good crc) but too short packet (and then
sends the right one on retransmit or sometimes just hangs) :-). On FreeBSD this 
in /etc/rc.conf does the trick:

ifconfig_sk0="up mtu 9000 media 1000baseSX mediaopt full-duplex"
ifconfig_sk1="up mtu 9000 media 1000baseSX mediaopt full-duplex"

same applies to Cat5 taps such as the Century tap as well.