TCP retransmission counters for xfer
tias at netnod.se
Fri Nov 30 13:15:20 UTC 2012
In an attempt to catch slow zone transfers, I'd like to see some
statistics for each TCP session running a xfer.
As I'm running linux I had a look in /proc/net/tcp and if I read things
right, the kernel is actually collecting the number of retransmissions
for each session.
netstat will not suffice, as it only shows retransmissions globally, not
Looking at linux tcp.h there is a struct tcp_info that seems to hold a
lot of info, retransmissions included. I have no idea how other
platforms do this if at all.
Now some might say "Use packet capture", but that will be hard as I'm
running IPsec transport mode.
The best alternative, from my perspective would be if bind could log a
little more info after a xfer is done, like retransmissions, pmtu, rtt,
mss. Perhaps not by default, but in debug or something.
I hope you get my point. Any suggestion or idea is appreciated.
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