[185675] in North American Network Operators' Group
Re: Long-haul 100Mbps EPL circuit throughput issue
daemon@ATHENA.MIT.EDU (Pablo Lucena)
Fri Nov 6 00:17:49 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <CAP-guGUycg9mcVKYxB_fXXVCLhNpA6unkCmoiODrFmn5i7aDOw@mail.gmail.com>
From: Pablo Lucena <plucena@coopergeneral.com>
Date: Fri, 6 Nov 2015 00:17:26 -0500
To: William Herrin <bill@herrin.us>
Cc: NANOG Operators' Group <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
>
>
> Modern TCPs support and typically use window scaling (RFC 1323). You
> may not notice it in packet dumps because the window scaling option is
> negotiated once for the connection, not repeated in every packet.
>
>
Absolutely. Most host OS should support this by now. Some test utilities
however, like iperf (at least the versions I've used) default to a 16 bit
window size though.
The goal of my response was to allude to the fact that TCP relies on
windowing unlike UDP, thus explaining the discrepancies.
This is a good article outlining these details:
https://www.edge-cloud.net/2013/06/measuring-network-throughput/
