[126157] in North American Network Operators' Group
Re: Emulating ADSL bandwidth shaping
daemon@ATHENA.MIT.EDU (Aria Stewart)
Tue May 4 00:16:13 2010
From: Aria Stewart <aredridel@nbtsc.org>
In-Reply-To: <4BDF922B.5080408@zill.net>
Date: Mon, 3 May 2010 22:15:32 -0600
To: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On May 3, 2010, at 9:19 PM, Patrick Giagnocavo wrote:
>> - do ISPs typically use token bucket filters with large bursts to =
shape traffic?
>> - what kind of burst sizes and latencies/limits are typically used =
for
>> the filter?
>>=20
>=20
> You will definitely have to account for latency.
>=20
> For emulating cable traffic, latencies (in the USA) will be about
> 60-80ms to typical sites. Burst mode in my experience occurs only for
> about the first 15 seconds, then is throttled back (though not always;
> seems to depend on time of day).
>=20
And queues of 1 second at line rate are not uncommon, so if you load the =
link, things lag.=20
> For DSL, I seem to recall latency being about 90-110ms (note, I =
haven't
> used DSL in many years). Burst mode was generally not noticeable or
> available, that is, you got the same speed regardless of downloading a
> 1MB jpeg or a 640MB .iso file.
Now more typically 40ms. And yeah, no bursts over normal line rate. Most =
turn down line rate for other plans, not shape.=
