IETF Logo Mail Archive

Re: [OPSAWG] draft-gharris-opsawg-pcap.txt --- FCS length description

Carsten Bormann <cabo@tzi.org> Tue, 22 December 2020 03:03 UTC

Return-Path: <cabo@tzi.org>
X-Original-To: opsawg@ietfa.amsl.com
Delivered-To: opsawg@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id E938B3A08FA for <opsawg@ietfa.amsl.com>; Mon, 21 Dec 2020 19:03:50 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.897
X-Spam-Level:
X-Spam-Status: No, score=-1.897 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id f9BkXktVwbid for <opsawg@ietfa.amsl.com>; Mon, 21 Dec 2020 19:03:47 -0800 (PST)
Received: from gabriel-vm-2.zfn.uni-bremen.de (gabriel-vm-2.zfn.uni-bremen.de [134.102.50.17]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id BE6F03A08F4 for <opsawg@ietf.org>; Mon, 21 Dec 2020 19:03:46 -0800 (PST)
Received: from [192.168.217.118] (p548dca87.dip0.t-ipconnect.de [84.141.202.135]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gabriel-vm-2.zfn.uni-bremen.de (Postfix) with ESMTPSA id 4D0Ll43z4RzyTd; Tue, 22 Dec 2020 04:03:44 +0100 (CET)
Content-Type: multipart/signed; boundary="Apple-Mail=_EA1441F7-3046-45F5-8FC7-056A53139CD1"; protocol="application/pgp-signature"; micalg="pgp-sha256"
Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.4\))
From: Carsten Bormann <cabo@tzi.org>
In-Reply-To: <12531.1608597102@localhost>
Date: Tue, 22 Dec 2020 04:03:44 +0100
Cc: Pcap-ng file format <pcap-ng-format@winpcap.org>, tcpdump-workers <tcpdump-workers@lists.tcpdump.org>, opsawg@ietf.org
X-Mao-Original-Outgoing-Id: 630299023.443329-41139b754973014154a20fbc5cbc62db
Content-Transfer-Encoding: quoted-printable
Message-Id: <045B17F6-EC38-461D-98BA-F19B002A780F@tzi.org>
References: <12531.1608597102@localhost>
To: Michael Richardson <mcr+ietf@sandelman.ca>
X-Mailer: Apple Mail (2.3608.120.23.2.4)
Archived-At: <https://mailarchive.ietf.org/arch/msg/opsawg/8VYO7MSROlXugdzmb73RFK_jg1k>
Subject: Re: [OPSAWG] draft-gharris-opsawg-pcap.txt --- FCS length description
X-BeenThere: opsawg@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: OPSA Working Group Mail List <opsawg.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/opsawg>, <mailto:opsawg-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/opsawg/>
List-Post: <mailto:opsawg@ietf.org>
List-Help: <mailto:opsawg-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/opsawg>, <mailto:opsawg-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 22 Dec 2020 03:03:51 -0000

On 2020-12-22, at 01:31, Michael Richardson <mcr+ietf@sandelman.ca> wrote:
> 
> #define LT_FCS_LENGTH(x)		(((x) & 0xF0000000) >> 28)
> #define LT_FCS_DATALINK_EXT(x)		((((x) & 0xF) << 28) | 0x04000000)
> 
> this suggests that the FCS length is really only 3 bits

4 bits, really (assuming 32-bit unsigned integers).

Grüße, Carsten

v2.23.0 | Report a Bug | By Email