ALTO

"Application-Layer Traffic Optimization (ALTO) Protocol" (RFC 7285) leverages HTTP/1.1 and is designed for the simple, sequential request-reply use case, in which an ALTO client requests a sequence of information resources and the server responds with the complete content of each resource, one at a time.

RFC 8895, which describes ALTO incremental updates using Server-Sent Events (SSE), defines a multiplexing protocol on top of HTTP/1.x, so that an ALTO server can incrementally push resource updates to clients whenever monitored network information resources change, allowing the clients to monitor multiple resources at the same time. However, HTTP/2 and later versions already support concurrent, non-blocking transport of multiple streams in the same HTTP connection.

To take advantage of newer HTTP features, this document introduces the ALTO Transport Information Publication Service (TIPS). TIPS uses an incremental RESTful design to give an ALTO client the new capability to explicitly and concurrently (in a non-blocking manner) request (or pull) specific incremental updates using HTTP/2 or HTTP/3, while still functioning for HTTP/1.1.

The cost metric is a basic concept in Application-Layer Traffic

Optimization (ALTO), and different applications may use different

types of cost metrics. Since the ALTO base protocol (RFC 7285)

defines only a single cost metric (namely, the generic "routingcost"

metric), if an application wants to issue a cost map or an endpoint

cost request in order to identify a resource provider that offers

better performance metrics (e.g., lower delay or loss rate), the base

protocol does not define the cost metric to be used.

This document addresses this issue by extending the specification to

provide a variety of network performance metrics, including network

delay, delay variation (a.k.a. jitter), packet loss rate, hop count,

and bandwidth.

There are multiple sources (e.g., estimations based on measurements

or a Service Level Agreement) available for deriving a performance

metric. This document introduces an additional "cost-context" field

to the ALTO "cost-type" field to convey the source of a performance

metric.

This document is an extension to the base Application-Layer Traffic Optimization (ALTO) protocol. It extends the ALTO cost map and ALTO property map services so that an application can decide to which endpoint(s) to connect based not only on numerical/ordinal cost values but also on fine-grained abstract information regarding the paths. This is useful for applications whose performance is impacted by specific components of a network on the end-to-end paths, e.g., they may infer that several paths share common links and prevent traffic bottlenecks by avoiding such paths. This extension introduces a new abstraction called the "Abstract Network Element" (ANE) to represent these components and encodes a network path as a vector of ANEs. Thus, it provides a more complete but still abstract graph representation of the underlying network(s) for informed traffic optimization among endpoints.

This document creates a new IANA registry for tracking cost modes supported by the Application-Layer Traffic Optimization (ALTO) Protocol. Also, this document relaxes a constraint that was imposed by the ALTO specification on allowed cost mode values.

This document updates RFC 7285.

This document specifies an extension to the base Application-Layer Traffic Optimization (ALTO) Protocol that generalizes the concept of "endpoint properties", which have been tied to IP addresses so far, to entities defined by a wide set of objects. Further, these properties are presented as maps, similar to the network and cost maps in the base ALTO Protocol. While supporting the endpoints and related Endpoint Property Service defined in RFC 7285, the ALTO Protocol is extended in two major directions. First, from endpoints restricted to IP addresses to entities covering a wider and extensible set of objects; second, from properties for specific endpoints to entire entity property maps. These extensions introduce additional features that allow entities and property values to be specific to a given information resource. This is made possible by a generic and flexible design of entity and property types.

The Content Delivery Networks Interconnection (CDNI) framework in RFC 6707 defines a set of protocols to interconnect CDNs to achieve multiple goals, including extending the reach of a given CDN. A CDNI Request Routing Footprint & Capabilities Advertisement interface (FCI) is needed to achieve the goals of a CDNI. RFC 8008 defines the FCI semantics and provides guidelines on the FCI protocol, but the exact protocol is not specified. This document defines a new Application-Layer Traffic Optimization (ALTO) service, called "CDNI Advertisement Service", that provides an implementation of the FCI, following the guidelines defined in RFC 8008.

The Application-Layer Traffic Optimization (ALTO) protocol (RFC 7285) provides network-related information, called network information resources, to client applications so that clients can make informed decisions in utilizing network resources. This document presents a mechanism to allow an ALTO server to push updates to ALTO clients to achieve two benefits: (1) updates can be incremental, in that if only a small section of an information resource changes, the ALTO server can send just the changes and (2) updates can be immediate, in that the ALTO server can send updates as soon as they are available.

This document is an extension to the base Application-Layer Traffic Optimization (ALTO) protocol. It extends the ALTO cost information service so that applications decide not only 'where' to connect but also 'when'. This is useful for applications that need to perform bulk data transfer and would like to schedule these transfers during an off-peak hour, for example. This extension introduces the ALTO Cost Calendar with which an ALTO Server exposes ALTO cost values in JSON arrays where each value corresponds to a given time interval. The time intervals, as well as other Calendar attributes, are specified in the Information Resources Directory and ALTO Server responses.

The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. ALTO is realized by a client-server protocol. Before an ALTO client can ask for guidance, it needs to discover one or more ALTO servers that can provide suitable guidance.

In some deployment scenarios, in particular if the information about the network topology is partitioned and distributed over several ALTO servers, it may be necessary to discover an ALTO server outside of the ALTO client's own network domain, in order to get appropriate guidance. This document details applicable scenarios, itemizes requirements, and specifies a procedure for ALTO cross-domain server discovery.

Technically, the procedure specified in this document takes one IP address or prefix and a U-NAPTR Service Parameter (typically, "ALTO:https") as parameters. It performs DNS lookups (for NAPTR resource records in the "in-addr.arpa." or "ip6.arpa." trees) and returns one or more URIs of information resources related to that IP address or prefix.

The Application-Layer Traffic Optimization (ALTO) protocol, specified in RFC 7285, defines several services that return various metrics describing the costs between network endpoints.

This document defines a new service that allows an ALTO Client to retrieve several cost metrics in a single request for an ALTO filtered cost map and endpoint cost map. In addition, it extends the constraints to further filter those maps by allowing an ALTO Client to specify a logical combination of tests on several cost metrics.

Many Internet applications are used to access resources such as pieces of information or server processes that are available in several equivalent replicas on different hosts. This includes, but is not limited to, peer-to-peer file sharing applications. The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. This memo discusses deployment-related issues of ALTO. It addresses different use cases of ALTO such as peer-to-peer file sharing and Content Delivery Networks (CDNs) and presents corresponding examples. The document also includes recommendations for network administrators and application designers planning to deploy ALTO, such as recommendations on how to generate ALTO map information.

The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. ALTO is realized by a client-server protocol. Before an ALTO client can ask for guidance, it needs to discover one or more ALTO servers.

This document specifies a procedure for resource-consumer-initiated ALTO server discovery, which can be used if the ALTO client is embedded in the resource consumer.

Applications using the Internet already have access to some topology information of Internet Service Provider (ISP) networks. For example, views to Internet routing tables at Looking Glass servers are available and can be practically downloaded to many network application clients. What is missing is knowledge of the underlying network topologies from the point of view of ISPs. In other words, what an ISP prefers in terms of traffic optimization -- and a way to distribute it.

The Application-Layer Traffic Optimization (ALTO) services defined in this document provide network information (e.g., basic network location structure and preferences of network paths) with the goal of modifying network resource consumption patterns while maintaining or improving application performance. The basic information of ALTO is based on abstract maps of a network. These maps provide a simplified view, yet enough information about a network for applications to effectively utilize them. Additional services are built on top of the maps.

This document describes a protocol implementing the ALTO services. Although the ALTO services would primarily be provided by ISPs, other entities, such as content service providers, could also provide ALTO services. Applications that could use the ALTO services are those that have a choice to which end points to connect. Examples of such applications are peer-to-peer (P2P) and content delivery networks.

Many Internet applications have a need for object-based security mechanisms in addition to security mechanisms at the network layer or transport layer. For many years, the Cryptographic Message Syntax (CMS) has provided a binary secure object format based on ASN.1. Over time, binary object encodings such as ASN.1 have become less common than text-based encodings, such as the JavaScript Object Notation (JSON). This document defines a set of use cases and requirements for a secure object format encoded using JSON, drawn from a variety of application security mechanisms currently in development.

This document describes experiments that clarify how an approach similar to Application-Layer Traffic Optimization (ALTO) was effective in reducing network traffic. These experiments were performed in Japan by the P2P Network Experiment Council in an attempt to harmonize peer-to-peer (P2P) technology with network infrastructure. Based on what was learned from these experiments, this document provides some suggestions that might be useful for the ALTO architecture and especially for application-independent ALTO- like server operation.

Many Internet applications are used to access resources, such as pieces of information or server processes that are available in several equivalent replicas on different hosts. This includes, but is not limited to, peer-to-peer file sharing applications. The goal of Application-Layer Traffic Optimization (ALTO) is to provide guidance to applications that have to select one or several hosts from a set of candidates capable of providing a desired resource. This guidance shall be based on parameters that affect performance and efficiency of the data transmission between the hosts, e.g., the topological distance. The ultimate goal is to improve performance or Quality of Experience in the application while reducing the utilization of the underlying network infrastructure.

This document enumerates requirements for specifying, assessing, or comparing protocols and implementations. This document is not an Internet Standards Track specification; it is published for informational purposes.

A significant part of the Internet traffic today is generated by peer-to-peer (P2P) applications used originally for file sharing, and more recently for real-time communications and live media streaming. Such applications discover a route to each other through an overlay network with little knowledge of the underlying network topology. As a result, they may choose peers based on information deduced from empirical measurements, which can lead to suboptimal choices. This document, a product of the P2P Research Group, presents a survey of existing literature on discovering and using network topology information for Application-Layer Traffic Optimization. This document is not an Internet Standards Track specification; it is published for informational purposes.

Distributed applications -- such as file sharing, real-time communication, and live and on-demand media streaming -- prevalent on the Internet use a significant amount of network resources. Such applications often transfer large amounts of data through connections established between nodes distributed across the Internet with little knowledge of the underlying network topology. Some applications are so designed that they choose a random subset of peers from a larger set with which to exchange data. Absent any topology information guiding such choices, or acting on suboptimal or local information obtained from measurements and statistics, these applications often make less than desirable choices.

This document discusses issues related to an information-sharing service that enables applications to perform better-than-random peer selection. This memo provides information for the Internet community.