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-   -   Congestion control (https://www.linuxquestions.org/questions/linux-networking-3/congestion-control-4175491608/)

manolakis 01-17-2014 09:09 AM

Congestion control
 
Hello,

I would like to ask if anyone knows how is it possible to determine what will be the appropriate receive window size for a receiver in a Server-Client application, especially if the application implements a congestion control algorithm (ex.Reno)?

Thank you.

unSpawn 01-18-2014 04:49 AM

The receive window size consists of two values: a fixed maximum (/proc/sys/net/core/rmem_max: mucking with changing of values is not suggested unless you know you need to and you know what you are doing) and the current size which is flexibly based on the amount of data not yet received from the sender. The latter, basically a countdown of bytes not received yet, is advertised in ACKs as a 16-bit window value. Sloppy AWK but on the server this should more or less show the window settings it advertises to clients:
Code:

tcpdump -n -nn -N -i [ethernet_device_name] 'tcp[tcpflags] & (tcp-syn|tcp-ack) == tcp-ack'|awk '{if($10 = "win") print $5,$11}'

manolakis 01-22-2014 05:12 AM

unSpawn,

Thank you very much for your reply. Could I also ask you which congestion control algorithm do you believe is more efficient?


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