1.5 Applicability Statement

The Content Information Data Structure is applicable in a context where both content servers and peers support the protocols in the Peer Content Caching and Retrieval Framework.<1>

This framework is intended primarily for settings where content servers are available only over a link that is low-bandwidth, high-latency, or both, while peers are available over higher-bandwidth, lower latency links. The data structure is provided by content servers that support it to clients that support using it to obtain their requested content from peers instead of the server.

A requesting peer contacts the content server to obtain the Content Information for the specific document it wishes to download. The peer then embeds identifiers from the Content Information in the Peer Content Caching and Retrieval: Discovery Protocol probe message that it sends out to the peer caches, as specified in [MS-PCCRD] section 2.2.2.1. A peer cache receiving the probe message takes these identifiers and replies to the requesting peer if they match the Content Information cached locally. The actual content retrieval thus uses primarily the higher-bandwidth, lower-latency links.