[ippm] Robert Wilton's Discuss on draft-ietf-ippm-ioam-direct-export-09: (with DISCUSS and COMMENT)
Robert Wilton via Datatracker <noreply@ietf.org> Thu, 30 June 2022 10:37 UTC
Return-Path: <noreply@ietf.org>
X-Original-To: ippm@ietf.org
Delivered-To: ippm@ietfa.amsl.com
Received: from ietfa.amsl.com (localhost [IPv6:::1]) by ietfa.amsl.com (Postfix) with ESMTP id 965CBC14CF10; Thu, 30 Jun 2022 03:37:10 -0700 (PDT)
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 7bit
From: Robert Wilton via Datatracker <noreply@ietf.org>
To: The IESG <iesg@ietf.org>
Cc: draft-ietf-ippm-ioam-direct-export@ietf.org, ippm-chairs@ietf.org, ippm@ietf.org, tpauly@apple.com, tpauly@apple.com
X-Test-IDTracker: no
X-IETF-IDTracker: 8.5.1
Auto-Submitted: auto-generated
Precedence: bulk
Reply-To: Robert Wilton <rwilton@cisco.com>
Message-ID: <165658543060.26121.15996942392973121368@ietfa.amsl.com>
Date: Thu, 30 Jun 2022 03:37:10 -0700
Archived-At: <https://mailarchive.ietf.org/arch/msg/ippm/QWBs6Xgylp0Xr3QRa6Y79snwVBM>
Subject: [ippm] Robert Wilton's Discuss on draft-ietf-ippm-ioam-direct-export-09: (with DISCUSS and COMMENT)
X-BeenThere: ippm@ietf.org
X-Mailman-Version: 2.1.39
List-Id: IETF IP Performance Metrics Working Group <ippm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/ippm>, <mailto:ippm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/ippm/>
List-Post: <mailto:ippm@ietf.org>
List-Help: <mailto:ippm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/ippm>, <mailto:ippm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 30 Jun 2022 10:37:10 -0000
Robert Wilton has entered the following ballot position for draft-ietf-ippm-ioam-direct-export-09: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/about/groups/iesg/statements/handling-ballot-positions/ for more information about how to handle DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-ippm-ioam-direct-export/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- Hi, I had a couple of minor discuss comments to clarify a couple of points that seemed unclear: 1) Definition of Sequence Number: Sequence Number An optional 32-bit sequence number starting from 0 and increasing by 1 for each following monitored packet from the same flow at the encapsulating node. The Sequence Number, when combined with the Flow ID, provides a convenient approach to correlate the exported data from the same user packet. Please can you clarify. Is this every packet in the flow (presumably not)? Does monitored packet means just those with the DEX option? Could it include other packets 2. Optional field ordering. Optional fields The optional fields, if present, reside after the Reserved field. The order of the optional fields is according to the respective bits that are enabled in the Extension-Flags field. Each optional field is 4 octets long. Please can clarify that the order is from most significant bit to least significant bit of the option field. 3. Allocation is based on the "RFC Required" procedure, as defined in [RFC8126]. Given the number of extensions is so limited, is RFC required (e.g. allows ISE) really a strict enough allocation policy? Regards, Rob ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- Here are my non-blocking comments: 1. This draft has evolved from combining some of the concepts of PBT-I from [I-D.song-ippm-postcard-based-telemetry] with immediate exporting from [I-D.ietf-ippm-ioam-flags]. I'm not sure that this paragraph is really helpful now, and could probably be deleted - you could use the datatracker to indicate the document history and which previous drafts this document replaces. 2. N >> M I'm assuming that by ">>", this means much greater than? It would be better use words here, or at least define what this means (e.g., as opposed to a bit-shift). 3. An IOAM node MAY maintain a counter or a set of counters that count the events in which the IOAM node receives a packet with the DEX Option-Type and does not collect and/or export data due to the rate limits. Given that this is a MAY, I wasn't sure that this really specifies anything, I guess that it is just offering a suggestion. 4. Exported packets SHOULD NOT be exported over a path or a tunnel that is subject to IOAM direct exporting. Furthermore, IOAM encapsulating nodes that can identify a packet as an IOAM exported packet MUST NOT push a DEX Option-Type into such a packet. This requirement is intended to prevent nested exporting and/or exporting loops. It was unclear to me how that that SHOULD NOT can really be enforced, if the exported packets are allowed to leave the limited domain. Perhaps the "SHOULD NOT" should be limited to the domain where IOAM is operating? 5. transit or decapsulating IOAM node that receives an unknown IOAM- Option-Type ignores it (as defined in [RFC9197]), and specifically nodes that do not support the DEX Option-Type ignore it. Note that as per [RFC9197] a decapsulating node removes the IOAM encapsulation and all its IOAM-Option-Types, and specifically in the case where one of these options is a (possibly unknown) DEX Option-Type. The ability to skip over a (possibly unknown) DEX Option-Type in the parsing or in the decapsulation procedure is dependent on the specific encapsulation, which is outside the scope of this document. For example, when IOAM is encapsulated in IPv6 I found the sentence from "Note that ..." to be somewhat unclear. 6. Option-Type Format Would it be more helpful to explicitly specify what the length is. I.e., X bytes + 4 * number of set bits in the Extension-Flags? 7. Extension-Flags More a question for my own knowledge: I presume that the length calculation (i.e., checking for the count of set bits) can be performed efficiently? I.e., if calculating the length is important on any fast path. 8. subject to birthday problem conflicts, while centralized Would it be helpful to spell out what is meant by "birthday problem conflicts", or perhaps include an informative reference to the wiki page? Nits: N>100 => N > 100
- [ippm] Robert Wilton's Discuss on draft-ietf-ippm… Robert Wilton via Datatracker
- Re: [ippm] Robert Wilton's Discuss on draft-ietf-… Tal Mizrahi