[ i deleted some of this thread already & am too lazy to search archives
to see if you posted tcpdumps, i'll go off what's in my mailbox. ]
On Thu, Jun 19, 2008 at 02:22:39PM -0700, Christopher Hunt wrote:
> Thanks for the reply. I understand that those values are not
> recommended and in fact i do not use them outside of the lab. I am,
> however, struggling to understand how TCP reacts to very very low burst
> levels. What mechanism is causing such low throughput as the
> tcp_receive_window values are not low?
the window settings may not be low, but i'd imagine that if you sniffed
the traffic the actual window size never really ramped up.
assuming this covers the entirety of the transaction:
conformed 188 packets, 260984 bytes; action: transmit
exceeded 65 packets, 97206 bytes; action: drop
you dropped 25% of the packets sent. the window never would have scaled
up and even if the window did scale up before this policy was applied
it would drop to 0 and slow start would begin again.
tcp doesn't send an orgy of packets (a 16k window of packets) and then
figure out how many landed where they should, it ramps / scales UP TO
the max window size. it was never afforded the opportunity to do so due
to your incredibly small burst size causing these drops.
-- bill
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