ALTO Transport Analysis

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Table of Contents

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.¶

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.¶

3. Capabilities

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.¶

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