Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BF9FAC10F14 for ; Wed, 10 Apr 2019 07:23:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 906F4217D6 for ; Wed, 10 Apr 2019 07:23:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728977AbfDJHX0 (ORCPT ); Wed, 10 Apr 2019 03:23:26 -0400 Received: from s3.sipsolutions.net ([144.76.43.62]:40398 "EHLO sipsolutions.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726931AbfDJHX0 (ORCPT ); Wed, 10 Apr 2019 03:23:26 -0400 Received: by sipsolutions.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1hE7Zj-0006AG-2f; Wed, 10 Apr 2019 09:23:15 +0200 Message-ID: <46474c61d7748042cc0a1f23773186786020638e.camel@sipsolutions.net> Subject: Re: gsmtap design/extensions? From: Johannes Berg To: Vadim Yanitskiy Cc: Harald Welte , OpenBSC Mailing List , Sean Tranchetti , radiotap@netbsd.org, Dan Williams , netdev@vger.kernel.org, linux-wireless@vger.kernel.org, Aleksander Morgado , Subash Abhinov Kasiviswanathan , =?ISO-8859-1?Q?Bj=F8rn?= Mork Date: Wed, 10 Apr 2019 09:23:13 +0200 In-Reply-To: (sfid-20190410_083605_324978_F3549EC8) References: (sfid-20190410_083605_324978_F3549EC8) Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-2.fc28) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Wed, 2019-04-10 at 13:35 +0700, Vadim Yanitskiy wrote: > Hello Johannes, > > FYI, there already was a discussion about GSMTAPv3: > > https://www.youtube.com/watch?v=vum9jzavZi0&list=PL07C78AF831FFE8F9&index=10 > > but unfortunately, nobody has invested time into this (yet?). 2012! But, umm, I don't really have time for a whole video right now - anyone have the slides? :-) But yeah, the first slides look sensible :-) > > 1) Why the design with encapsulating it in UDP? > > This gives us a possibility to "demux" multiple GSMTAP streams on the > receiving side, e.g. if you are running multiple processes. Not sure I get this, but I also don't really care all that much. It's just a pretty strange design if the kernel were to output this, I'm not even sure how I'd do that properly. I don't want to be generating UDP packets there... Perhaps we can define something (GSMTAPv3) to not really care how it's encapsulated, and for 'native' packet captures like what I want on Linux when integrated with the driver, actually use an ARPHDR_GSMTAP, and encapsulate in UDP when you create it in an application and want to send it elsewhere, rather than just writing it to a pcap file? johannes