From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: Re: SCTP research inquiry Date: Wed, 03 Sep 2014 19:22:46 +0200 Message-ID: <54074E66.7000200@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev To: Kostantinos Katsaros Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33272 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756292AbaICRWu (ORCPT ); Wed, 3 Sep 2014 13:22:50 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 09/03/2014 07:07 PM, Kostantinos Katsaros wrote: > Dear NetDev list, > > I am a researcher from Univ. of Surrey. I know that this list is > mainly for developers of linux-kernel but I want to ask for some help > to understand the SCTP implementation and pointers to some aspects. > > What I would actually like to do, is to modify the default SCTP > operation with respect to primary/secondary interface selection and > analyse it in simulations with NS-3. However, I haven't found an API > or some other help and I was advised to contact this list. I know that > NS-3 is capable of using linux-kernel implementations through the use > of DCE, but my issue here is in the SCTP implementation. > > There a few questions I have in a basic scenario with two nodes > connected via 2 interfaces. > > - How can I dynamically select which of the two interfaces is primary? > Which method is responsible or should be called to switch? Have a look at the implementation of sctp_select_active_and_retran_path() and sctp_assoc_choose_alter_transport() with sctp_assoc_update_retran_path(). Make sure you use a latest 3.17 rcX as it contains the latest changes to it (which you will find with some more explanation in the git log under net/sctp/). > - I guess that SCTP has some variable holding the estimated RTT on > each path (also used for calculating RTO). Is this accessible and how? > I would like to use this as a triggering mechanism to the switch > method above. In principle select the path with the minimum RTT. > > - In a similar way of TCP Westwood (Plus), I would like to estimate > the available bandwidth and use this as trigger. > > - Finally, I want to monitor the ratio (packets or bytes sent) on each > of the available paths. How can I implement such mechanism? Do I have > to implement a 'sniffer'? > > > I would appreciate any help, pointers, code snippets. > > > Regards, > > Kostas > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >