IETF is designing a new service called ALTO (Application Layer
traffic Optimization) that includes a "Network Map Service", an
"Endpoint Cost Service" and an "Endpoint (EP) Ranking Service" and
thus incentives for application clients to connect to ISP preferred
Endpoints. These services provide a view of the Network Provider
(NP) topology to overlay clients.
The present draft proposes a light way to extend the information
provided by the current ALTO protocol in two ways. First, including
information on multiple Cost Types in a single ALTO transaction
provides a better mapping of the Selected Endpoints to needs of the
growing diversity of Content and Resources Networking Applications
and to the network conditions. Second, one ALTO query and response
exchange on N Cost Types is faster and lighter than N single cost
transactions. All this also helps producing a faster and more robust
choice when multiple Endpoints need to be selected.