Application-Layer Traffic Optimization (ALTO)

Project type: Main

ALTO is a protocol defined by IETF with functions to provide network information to applications.

Specifically, ALTO defines abstractions and services to provide simplified network views and network services to guide the application usage of network resources, including cost. It includes five services:

1. Cost map service: ALTO's cost map provides costs between defined groupings.
2. Network map service: This service provides aggregate information to ALTO clients in the form of ALTO network maps.
3. Filtered map service: This service allows ALTO clients to send a parameter-based query to an ALTO server and request for a more specific network map and/or cost map.
4. Endpoint property service: This service allows ALTO clients to look up properties for each individual endpoint.
5. Endpoint cost service: This service allows an ALTO server to return the costs of direct endpoints.

ALTO implementation in ODL includes both MD-SAL and AD-SAL models; it also includes services. The alto-manager is a command-line tool to generate network maps and cost maps using ALTO.

These services, the alto-hosttracker service for example, rely on the L2 switch module and generate a network map, a corresponding cost map, and the endpoint cost service.