From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from uplift.swm.pp.se (ipv6.swm.pp.se [IPv6:2a00:801::f]) (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 9232921F1B5 for ; Mon, 1 Jul 2013 21:48:18 -0700 (PDT) Received: by uplift.swm.pp.se (Postfix, from userid 501) id D297C9C; Tue, 2 Jul 2013 06:48:14 +0200 (CEST) Received: from localhost (localhost [127.0.0.1]) by uplift.swm.pp.se (Postfix) with ESMTP id CD09C9A; Tue, 2 Jul 2013 06:48:14 +0200 (CEST) Date: Tue, 2 Jul 2013 06:48:14 +0200 (CEST) From: Mikael Abrahamsson To: Juliusz Chroboczek In-Reply-To: <871u7hesmm.wl%jch@pps.univ-paris-diderot.fr> Message-ID: References: <20130701164607.GB12090@ens-lyon.fr> <871u7hesmm.wl%jch@pps.univ-paris-diderot.fr> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) Organization: People's Front Against WWW MIME-Version: 1.0 Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII Cc: Baptiste Jonglez , babel-users@lists.alioth.debian.org, bloat@lists.bufferbloat.net Subject: Re: [Bloat] [Babel-users] RTT stability inside a GRE tunnel 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, 02 Jul 2013 04:48:18 -0000 On Tue, 2 Jul 2013, Juliusz Chroboczek wrote: > Anybody seen anything similar? I don't know if this is the cause, but older gear from Extreme Networks (their end-of-90ties and beginning of 2000s), will do ICMP in slow-path when routing (even packets going through the device) and "everything else" in fast-path. This could cause latency spikes and PDV approximately similar to what's seen in the picture. The seen behaviour could also perhaps be caused by per-packet QoS settings in the path, where ICMP might have lower priority than GRE. I don't think this explanation is likely though. -- Mikael Abrahamsson email: swmike@swm.pp.se