10g residential CPE

Mikael Abrahamsson swmike at swm.pp.se
Sat Dec 26 17:55:26 UTC 2020


On Sat, 26 Dec 2020, Baldur Norddahl wrote:

> It is true there have been TCP improvements but you can very easily verify
> for yourself that it is very hard to get anywhere near 1 Gbps of actual
> transfer speed to destinations just 10 ms away. Try the nlnog ring network
> like this:
>
> gigabit at gigabit01:~$ iperf -c netnod01.ring.nlnog.net
> ------------------------------------------------------------
> Client connecting to netnod01.ring.nlnog.net, TCP port 5001
> TCP window size: 85.0 KByte (default)
> ------------------------------------------------------------
> [  3] local 185.24.168.23 port 50632 connected with 185.42.136.5 port 5001
> [ ID] Interval       Transfer     Bandwidth
> [  3]  0.0-10.0 sec   452 MBytes   379 Mbits/sec

Why would you just use 85KB of TCP window size?

That's not the problem of buffering (or lack thereof) along the path, that 
just not enough TCP window size for long-RTT high speed transfers.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se


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