The following are prerequisites for using this protocol:
The protocol client is required to have a set of blocks within a segment that it can offer to the hosted cache. Typically, these blocks are retrieved by a higher layer from the content server. The higher layer then provides these blocks to this protocol to offer to the hosted cache.
If HTTPS ([RFC2818]) is used as a transport, the hosted cache is required to be provisioned with a certificate and associated private key, and the client with the root certificate, such that both are compatible with HTTPS Server authentication (see [RFC2818]).
If the hosted cache is configured to require client authentication, both the client and the hosted cache are required to support SPNEGO-based HTTP authentication ([RFC4559] and [MS-SPNG]) within the HTTPS transport.
The client is an actively listening server-role peer, as described in the Peer Content Caching and Retrieval: Retrieval Protocol (PCCRR) framework [MS-PCCRR]. The port it is listening on is passed as part of the CONNECTION_INFORMATION field in the various request messages from the client to the hosted cache. This allows the hosted cache to use the PCCRR framework to connect to the client to retrieve data blocks in the segment.