[alto] Review for draft-ietf-alto-performance-metrics-12
Jensen Zhang <jingxuan.n.zhang@gmail.com> Tue, 13 October 2020 04:17 UTC
Return-Path: <jingxuan.n.zhang@gmail.com>
X-Original-To: alto@ietfa.amsl.com
Delivered-To: alto@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 5F4443A0DEE for <alto@ietfa.amsl.com>; Mon, 12 Oct 2020 21:17:49 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.098
X-Spam-Level:
X-Spam-Status: No, score=-2.098 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HTML_MESSAGE=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=gmail.com
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 PfusyroRlZ3N for <alto@ietfa.amsl.com>; Mon, 12 Oct 2020 21:17:47 -0700 (PDT)
Received: from mail-yb1-xb2d.google.com (mail-yb1-xb2d.google.com [IPv6:2607:f8b0:4864:20::b2d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 4AFC73A0F4D for <alto@ietf.org>; Mon, 12 Oct 2020 21:17:29 -0700 (PDT)
Received: by mail-yb1-xb2d.google.com with SMTP id l15so424420ybp.2 for <alto@ietf.org>; Mon, 12 Oct 2020 21:17:29 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to; bh=nuMdeEt3GnGi7R1m0UakCfxgrwftiLKkAwD0MjpfDQo=; b=LVuCrjpduzNsqxMVLBPWw9iGClsjVeBxB67CoWlm8QNH+pSaFazJIsByIg9g0REcAj Is+5HTnL1UsrRbN6rL/zpvgyv1+jWxE/Wcqwn2x3NK6WN6nqgnbsCZUa+grDs60XMMli uoz7pAv1WkOMi+WFbC4sQXOYyqirp5YtHSOIHItyRU44zYsiYDF5U6DieqHkvYxIdaJJ pMFqp4cY2/BA8ZrcOtPJcA4nEO+Q1CRlsRB+nQSOR49Rm8CjNVnRmp9R9H3jRHjOZJ1G x8twQQFj089YVuOE1TnwRDlvp8AAOyIB1RNNA45tW0ynjYhSF8khO5B3UpRBOXBozwrF 01pQ==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=nuMdeEt3GnGi7R1m0UakCfxgrwftiLKkAwD0MjpfDQo=; b=eMg8H77ZRWDMOUDkEWMukKp8t0gRa9K/RRUS9REupjUNy4EHyCYZfsMBM6uXT8knl6 6NTKrx6dKeEPDrJGCxOmI0jkHWfd1z/ps4fEKVqrXvniEovZtc/gHAEZsnhjCeHA2V+7 n5IG/kMO8OQ7FMk3HreZPQhQ2S1N4FnaAGKb7S1taEiCPllqF5TFzW1ox2h2eqX/Bq91 btBls6AxQ3sBr8FQxKEECj+8ujEO78yoq3BWfryWfCZ10RWeDORnrLDcqyFSGQYwA6Z1 lM31O0zGNm685tLvf8TZpyctE/17FBuGVzEps4nsAYj2Gflrggy1gARDQ9UpLvRchouF rXaA==
X-Gm-Message-State: AOAM531ElSmnOHuLGsmiLeVXoJ1JXPfpWzra/MQPxNwoLdEX2kMATfXu H5Jf+Jr0xHNv2VjDcICuYS2kQRMY/DuELOZA+hRDqKKb6zG+XA==
X-Google-Smtp-Source: ABdhPJzhUoF1oY2Hawpj9vlUYp+C8J8UCOPQqdUbW3bJE+YlJYFzQSuwwJuFK8Cvdw2+89lH7at6JZiS5P1K3wzK9/Q=
X-Received: by 2002:a25:840d:: with SMTP id u13mr37188059ybk.7.1602562648142; Mon, 12 Oct 2020 21:17:28 -0700 (PDT)
MIME-Version: 1.0
From: Jensen Zhang <jingxuan.n.zhang@gmail.com>
Date: Tue, 13 Oct 2020 00:17:16 -0400
Message-ID: <CAAbpuyo3YC68C+7YmUv69P++ybxCxivYkEDh4Sk0tPfXFCkhXg@mail.gmail.com>
To: IETF ALTO <alto@ietf.org>
Content-Type: multipart/alternative; boundary="0000000000005f76c405b185b1be"
Archived-At: <https://mailarchive.ietf.org/arch/msg/alto/qZrkPza-vEUcIqQMR3OJfk8G-uw>
Subject: [alto] Review for draft-ietf-alto-performance-metrics-12
X-BeenThere: alto@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: "Application-Layer Traffic Optimization \(alto\) WG mailing list" <alto.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/alto>, <mailto:alto-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/alto/>
List-Post: <mailto:alto@ietf.org>
List-Help: <mailto:alto-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/alto>, <mailto:alto-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 13 Oct 2020 04:17:49 -0000
Dear ALTOers and authors of draft-ietf-alto-performance-metrics-12, Below is my review for draft-ietf-alto-performance-metrics-12. Best regards, Jensen ============================================== General issue: The document is well written. I only have one question about the design part: the base ALTO protocol only uses the cost-mode to infer the value format, e.g., "numerical" infers the cost value MUST be a floating-point value; but this document requires different value formats for different cost-metrics, e.g., "delay-ow" requires the non-negative floating-point value, and "hopcount" requires the non-negative integer value. But based on Sec 11.3.2.3 of RFC7285, in the "constraints" field, "ALTO servers SHOULD use at least IEEE 754 double-precision floating point [IEEE.754.2008] to store the cost value". I wonder if a test constraint expression like "eq 3.1" for the cost-metric "hopcount" is valid. Should the ALTO server reject such a request? According to RFC7285, it should be valid. But according to this document, it is clearly always false. ============================================== Nits and writing suggestions: Section 1., paragraph 5: > The purpose of this document is to ensure proper usage of the > performance metrics defined in Table 1; it does not claim novelty of > the metrics. The Origin column of Table 1 gives the RFC which > defines each metric. Origin -> Origin Example (to be consistent with the table) > We can rough classify the performance metrics into two categories: > those derived from the performance of individual packets (i.e., one- > way delay, round-trip delay, delay variation, hop count, and loss > rate), and those related with bandwidth (TCP throughput, residue > bandwidth and max reservable bandwidth). These two categories are > defined in Section 3 and Section 4 respectively. Note that all > metrics except round trip delay are unidirectional. Hence, a client > will need to query both directions if needed. Section 2., paragraph 1: > When defining the metrics in Table 1, this document considers the > guidelines specified in [RFC6390], which requires fine-grained > specification of (i) Metric Name, (ii) Metric Description, (iii) > Method of Measurement or Calculation, (iv) Units of Measurement, (v) > Measurement Points, and (vi) Measurement Timing. In particular, for > each metric, this document defines (i) Metric Name, (ii) Metric > Description, and (iv) Units of Measurement. The Measurement Points > are always specified by the specific ALTO services; for example, > endpoint cost service is between the two end points. end points -> endpoints Section 2.1., paragraph 11: > A particular type of "estimation is direct "import", which indicates > that the value of the metric is imported directly from a specific > existing protocol or system. Specifying "import" as source instead source -> the source > of the more generic "estimation" may allow better tracing of > information flow. For an "import" metric, it is RECOMMENDED that the > "parameters" field provides details to the system from which raw data > is imported. In particular, one may notice that the set of end-to- > end metrics defined in Table 1 has large overlap with the set defined > in [RFC8571], in the setting of IGP traffic engineering performance > metrics for each link (i.e., unidirectional link delay, min/max > unidirectional link delay, unidirectional delay variation, > unidirectional link loss, unidirectional residual bandwidth, > unidirectional available bandwidth, unidirectional utilized > bandwidth). Hence, an ALTO server may use "import" to indicate that > its end-to-end metrics are computed from link metrics imported from > [RFC8571]. Section 2.2., paragraph 2: > percentile, with letter p followed by a number p: a number p -> a number Section 2.2., paragraph 16: > If a metric has no <stat> (and hence no - as well), the metric MUST recommend adding " surrounding -, or using dash character instead; if possible, giving the precise BNF grammar will be better, as I see some metrics names also include the dash character ("-"). > be considered as the 50 percentile (median). Since this scheme is > common for all metrics defined in this document, below we only > specify the base identifier. Section 3., paragraph 1: > This section introduces ALTO network performance metrics including > one way delay, round trip delay, delay variation, hop count, and > packet loss rate. They measure the "quality of experience" of the > stream of packets sent from a resource provider to a resource > consumer. The measures of each individual packet (pkt) can include > the delay from the time that the packet enters the network to the > time that the packet leaves the network (pkt.delay); the number of the time that -> the time when > network hops that the packet traverses (pkt.hopcount); and whether > the packet is dropped before reaching destination (pkt.dropped). The destination -> the destination > semantics of the performance metrics defined in this section is that > they are statistics (percentiles) computed from these measures; for > example, the x-percentile of the one-way delay is the x-percentile of > the set of delays {pkt.delay} for the packets in the stream. Section 3.1.3., paragraph 1: > Intended Semantics: To specify spatial and temporal aggregated delay spatial -> the spatial > of a stream of packets from the specified source and the specified > destination. The spatial aggregation level is specified in the query > context (e.g., PID to PID, or endpoint to endpoint). Section 3.1.4., paragraph 2: > "sla": Many networks provide delay in their application-level service > level agreements. It is RECOMMENDED that the "parameters" field of > an "sla" one-way delay metric provides a link ("link") to the SLA I assume that the second link (the one surrounding with ") means a field called "link", and the first link (the one without ") means the value of this field is a URI. Please make it clear. Adding an example could be better. > definition. Section 5.3., paragraph 2: > To address this issue, the only defined "routingcost" metric can be > ONLY "estimation". "ONLY" is not an RFC 2119 key word, doesn't have to be uppercase. Section 7., paragraph 3: > Since he This document requests the creation of the "ALTO Cost Source > Registry" with the following currently defined values: This paragraph seems to be incomplete and repeated to the next one. ==============================================
- [alto] Review for draft-ietf-alto-performance-met… Jensen Zhang