From: Mikael Abrahamsson <swmike@swm.pp.se>
To: Dave Taht <dave.taht@gmail.com>
Cc: cloneman <bufferbloat@flamingpc.com>,
bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] Does VDSL interleaving+FEC help bufferbloat?
Date: Fri, 4 Jan 2019 18:43:54 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.20.1901041840330.5601@uplift.swm.pp.se> (raw)
In-Reply-To: <CAA93jw6Sct=zuRHo2KdRqFhvMO-EYyKwrpxziSkd45w0TdxN7g@mail.gmail.com>
On Fri, 4 Jan 2019, Dave Taht wrote:
> dsl interleave was added primarily to make multicast udp tv streams work
> better (as they are very intolerant of packet loss). Often (as in free's
> implementation) these streams are "invisible" to the overlying IP
> applications. It typically adds at least 6ms of delay to an already slow
> technology.
ADSL2+ is very prone to short bursts of interference, so setting no
interleaving means quite high packet loss. Setting interleaving to 16ms
means FEC has a much better chance of correcting errors and thus reduce
packet loss.
At several jobs ago we actually had several different profiles for
customers, they could choose 1, 4 or 16ms interlaving depending on their
needs for gaming etc. The 1 and 4 ms interleaving targets had different
SNR margin targets so they were sacrificing speed for lower latency,
because that's the tradeoff you basically have to do with normal L4
protocols that end customers typically use.
--
Mikael Abrahamsson email: swmike@swm.pp.se
next prev parent reply other threads:[~2019-01-04 17:43 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-03 21:38 cloneman
2019-01-04 4:01 ` Jonathan Morton
2019-01-04 13:21 ` Simon Barber
2019-01-04 17:10 ` Dave Taht
2019-01-04 17:43 ` Mikael Abrahamsson [this message]
2019-01-04 17:52 ` Jan Ceuleers
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