2.1.1.4 PCCRD and WS-Discovery

PCCRD and WS-Discovery

Figure 5: PCCRD and WS-Discovery

The figure in this section shows the ordering of messages when the service is operating in distributed cache mode. The initial request (READ_HASH) for the content takes place in either SMB 2.1, SMB 3.x, or HTTP. The response with the hashes is returned in the same protocol that makes the request. After the content hashes have been received by the content client, the content client can determine whether any of the content exists within the local area network (LAN) where it resides. The content client does this by checking any local machine cache. Then, if the data is not available locally, it performs a Multicast WSD/MS-PCCRD Probe message with the hashes of the content.

Any server-role peers on the LAN that receive the Multicast Probe message and have the matching content via the Peer Content Caching and Retrieval Discovery Protocol ([MS-PCCRD]) respond with a Unicast Probe-Match message.

After the content client receives a match for content, it initiates one or more Peer Content Caching and Retrieval: Retrieval Protocol sessions, as described in [MS-PCCRR], (not shown in the figure) to retrieve the content from the server-role peer.