From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from uplift.swm.pp.se (swm.pp.se [212.247.200.143]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by huchra.bufferbloat.net (Postfix) with ESMTPS id 8366221F0B3 for ; Mon, 9 Dec 2013 22:48:07 -0800 (PST) Received: by uplift.swm.pp.se (Postfix, from userid 501) id 3C5EBA1; Tue, 10 Dec 2013 07:48:03 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by uplift.swm.pp.se (Postfix) with ESMTP id 341879A; Tue, 10 Dec 2013 07:48:03 +0100 (CET) Date: Tue, 10 Dec 2013 07:48:03 +0100 (CET) From: Mikael Abrahamsson To: Matthew Ford In-Reply-To: <26FB3C56-AF24-497C-943A-3FDAE7B88D08@isoc.org> Message-ID: References: <26FB3C56-AF24-497C-943A-3FDAE7B88D08@isoc.org> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: bloat Subject: Re: [Bloat] CFP: Workshop on Reducing Internet Latency X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.13 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Dec 2013 06:48:07 -0000 On Mon, 9 Dec 2013, Matthew Ford wrote: > The report of the Reducing Internet Latency workshop is now available: > > http://www.internetsociety.org/blog/2013/12/speeding-internet-reducing-latency Reading through this I generally like it. It's a good summary and introduction. However, this part: "Hiding packet losses in broadband lines using interleaving can add about 20ms of delay, even though modern transports and applications are robust to such low packet loss levels;" Having been part of a decently sized ADSL2+ deployment ISP, I have some experience with this and the above doesn't match them. We actually did get customer complaints when we were running ADSL2+ in fast-mode (no interleaving), that the customers were getting packet losses that affected their applications. So I would have liked the above to not say "broadband lines" but instead said ADSL(2+) broadband lines (because the above statement only relates to ADSL(2+) afaik), and also that the packet losses can be non-trivial for some and that ISPs don't turn on interleaving out of ignorance. It's hard to measure customer impact of "errored seconds" which is the only way the ISP can see packet losses. Also, these errored seconds can be quite severer when it comes to number of packets dropped. We actually did talk about having a self-service portal where the customer could choose their preferred profile, either fast (no interleaving), 4ms or 16 ms interleaving, and also their safety margin to 6, 9 or 12 dB. Fast or 4ms interleaving worked well with 12 dB SNR margin (which means lower latency but also lower access speeds), whereas 6dB margin often required 16ms interleaving to work well. -- Mikael Abrahamsson email: swmike@swm.pp.se