How to Quicken TCP Re-transmission?

[Bill Vermillion]

"Bits dont fail me now!" was what Brian Candler muttered
as he hastily typed this on Mon, May 22, 2006 at 14:06 :

> On Mon, May 22, 2006 at 07:51:33PM +0800, mag at intron.ac wrote:
> >     I want to transmit data between host A and host B. The link between
> > these two hosts is really bad: PING reports 30% packet loss

> How big are the pings? Try

>     ping -c100 -s1472 x.x.x.x
>
> to send 1500-byte pings (20 bytes IP header + 8 bytes ICMP
> header + 1472 bytes padding). This will give you a more
> realistic indication of packet loss for TCP transfers than the
> small pings you get by default.


The original poster noted that he had used -s1472 in his tests.

I had the same exact problem one time as the OP did.  Regular pings
would go through, data throughput was terrrible and going with
every larger packet sizes I found things really fell apart about
500 byte sizes.

In my case it was a bad card in a Cisco 12000 switch at the local
Level 3 facility where my servers were.  There were only about 6
other clients on that card, and since I made the call about 6AM
I was the first to notify them.

IOW - while your problem may indeed be somewhere in the link don't
discount the fact that the problem could be much closer.  Have you
tried a traceroute to see if it is at one particular link.

If your provider does not block it you might try the -R option
to ping the site to help pinpoint the source of the problem.

Bill
-- 
Bill Vermillion - bv @ wjv . com