ALTO Working Group Y. Yang Internet-Draft Yale University Intended status: Standards Track 24 October 2021 Expires: 27 April 2022 ALTO Transport Analysis draft-yang-alto-transport-analysis-00 Abstract Exposing network information to applications can be a basic function of computer networking. Such network information can be exposed to applications through either the data path or the control path. This informational document conducts a survey and analysis of existing capabilities and performance of protocols transporting network information to applications. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119][RFC8174] when, and only when, they appear in all capitals, as shown here. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 27 April 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. Yang Expires 27 April 2022 [Page 1] Internet-Draft ALTO Performance Cost Metrics October 2021 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Transport Designs . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Data Path Transport: TCP Options . . . . . . . . . . . . 3 2.2. Control Path Transport: ALTO . . . . . . . . . . . . . . 3 2.3. Control Path Transport: 3GPP NEF . . . . . . . . . . . . 3 3. Capabilities . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Information Model . . . . . . . . . . . . . . . . . . . . 3 3.2. Latency . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.3. Encoding Efficiency . . . . . . . . . . . . . . . . . . . 3 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 3 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 7.1. Normative References . . . . . . . . . . . . . . . . . . 4 7.2. Informative References . . . . . . . . . . . . . . . . . 4 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction Application-Layer Traffic Optimization (ALTO) provides a means for network applications to obtain network status information so that the applications can identify efficient application-layer traffic patterns using the networks. Recently, multiple extensions are proposed to the ALTO base protocol [RFC7285] to extend the ability of ALTO to transport network information to applications. The objective of this document is to put ALTO transport in the general context of transporting network information to applications, and evaluate ALTO and related protocols in their transport capabilities and efficiencies. Yang Expires 27 April 2022 [Page 2] Internet-Draft ALTO Performance Cost Metrics October 2021 2. Transport Designs There can be a large design space to transport network information to applications. Broadly, the designs can be classified into two types: data path transport and control path transport. An example of data path transport is TCP ECN options, which allows networks to convey network information to applications (i.e., endhosts). In a general data path design, as data packets traverse a network, the network elements update the field(s) of the data packets to provide network information. The recent development of in-network telemetry (INT) focuses on data path transport. This document focuses on TCP options based data path transport. ALTO base protocol, on the other hand, is a control path design. In a general control path design, the network information is collected by a service and exposed to applications. This document focuses on ALTO transport and 3GPP NEF. 2.1. Data Path Transport: TCP Options 2.2. Control Path Transport: ALTO 2.3. Control Path Transport: 3GPP NEF 3. Capabilities 3.1. Information Model The information model includes the following abilities: information availability, information selection, update control, etc. 3.2. Latency 3.3. Encoding Efficiency 4. Security Considerations There can be substantial security issues when transporting network information to applications. 5. IANA Considerations This informational document does not have IANA consideration. 6. Acknowledgments The author thanks many reviewers for their comments. Yang Expires 27 April 2022 [Page 3] Internet-Draft ALTO Performance Cost Metrics October 2021 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, DOI 10.17487/RFC2818, May 2000, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . 7.2. Informative References [Prometheus] Volz, J. and B. Rabenstein, "Prometheus: A Next-Generation Monitoring System", 2015. [Prophet] Gao, K., Zhang, J., and YR. Yang, "Prophet: Fast, Accurate Throughput Prediction with Reactive Flows", ACM/IEEE Transactions on Networking July, 2020. [RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S., Previdi, S., Roome, W., Shalunov, S., and R. Woundy, "Application-Layer Traffic Optimization (ALTO) Protocol", RFC 7285, DOI 10.17487/RFC7285, September 2014, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Author's Address Y. Richard Yang Yale University 51 Prospect St New Haven, CT 06520 United States of America Email: yry@cs.yale.edu Yang Expires 27 April 2022 [Page 4]