Application-Layer Traffic Optimization Working Group Charter
The ALTO working group was established in 2008 to devise a request/response protocol to allow a host to benefit from a server that is more cognizant of the network infrastructure than the host is.
The working group has developed an HTTP-based protocol and recent work has reported large-scale deployment of ALTO based solutions supporting applications such as content distribution networks (CDN).
ALTO is now proposed as a component for cloud-based interactive applications, large-scale data analytics, multi-cloud SD-WAN deployment, and distributed computing. In all these cases, exposing network information such as abstract topologies and network function deployment location helps applications.
To support these emerging uses, extensions are needed, and additional functional and architectural features need to be considered as follows:
Protocol extensions to support a richer and extensible set of policy attributes in ALTO information update request and response. Such policy attributes may indicate information dependency (e.g., ALTO path-cost/QoS properties with dependency on real-time network indications), optimization criteria (e.g., lowest latency/throughput network performance objective), and constraints (e.g., relaxation bound of optimization criteria, domain or network node to be traversed, diversity of paths).
Protocol extensions for facilitating operational automation tasks and improving transport efficiency. In particular, extensions to provide "pub/sub" mechanisms to allow the client to request and receive a diverse types (such as event-triggered/sporadic, continuous), customized feed of publisher-generated information. Efforts developed in other working groups such as MQTT Publish / Subscribe Architecture, WebSub?, Subscription to YANG Notifications will be considered, and issues such as scalability (e.g., using unicast or broadcast/multicast, and periodicity of object updates) should be considered.
The working group will investigate the configuration, management, and operation of ALTO systems and may develop suitable data models.
Extensions to ALTO services to support multi-domain settings. ALTO is currently specified for a single ALTO server in a single administrative domain, but a network may consist of multiple domains and the potential information sources may not be limited to a certain domain. The working group will investigate extending the ALTO framework to (1) specify multi-ALTO-server protocol flow and usage guidelines when an ALTO service involves network paths spanning multiple domains with multiple ALTO servers, and (2) extend or introduce ALTO services allowing east-west interfaces for multiple ALTO server integration and collaboration. The specifications and extensions should use existing services whenever possible. The specifications and extensions should consider realistic complexities including incremental deployment, dynamicity, and security issues such as access control, authorization (e.g., an ALTO server provides information for a network that the server has no authorization), and privacy protection in multi-domain settings.
The working group will update RFC 7971 to provide operational considerations for recent protocol extensions (e.g., cost calendar, unified properties, and path vector) and new extensions that the WG develops. New considerations will include decisions about the set of information resources (e.g., what metrics to use), notification of changes either in proactive or reactive mode (e.g., pull the backend, or trigger just-in-time measurements), aggregation/processing of the collected information (e.g., compute information and network information )according to the clients’ requests, and integration with new transport mechanisms (e.g., HTTP/2 and HTTP/3).
When the WG considers standardizing information that the ALTO server could provide, the following criteria are important to ensure real feasibility:
Can the ALTO server realistically provide (measure or derive) that information?
Is it information that the ALTO client cannot find easily some other way?
Is the distribution of the information allowed by the operator of the network? Does the exposure of the information introduce privacy and information leakage concerns?
Issues related to the specific content exchanged in systems that make use of ALTO are excluded from the WG's scope, as is the issue of dealing with enforcing the legality of the content. The WG will also not propose standards on how congestion is signaled, remediated, or avoided.
Apr 2021- Submit cdni request routing document to IESG as Proposed Standard
Apr 2021 - Submit path vector document to IESG as Proposed Standard
Apr 2021 - Submit alto performance metric document to IESG as Proposed Standard
Apr 2021 - Submit entity property map document to IESG as Proposed Standard