Windows exposes PNRP via a PNRP API for applications and services, as well as by extending the
PNRP peer names (also called
Authority. For
Classifier. The classifier uses a simple string to identify a service provided by a peer, which allows multiple services to be provided by the same device.
To create a PNRP ID, PNRP hashes the P2P ID and combines it with a unique 128-bit ID called the
PNRP Resolution and Publication
PNRP name resolution occurs in two phases:
Endpoint determination. In this phase, the requesting peer determines the IPv6 address associated with the peer responsible for publishing the PNRP ID of the desired service.
PNRP ID resolution. In this phase, once the requesting peer has located and confirmed the availability of the peer associated with the IPv6 address, it sends a PNRP request message for the PNRP ID of the service being requested. The peer providing the service replies to confirm the PNRP ID and can supply a comment and up to 4 KB of additional data, such as context information related to the service.
During the first phase, PNRP iterates over nodes while locating the publishing node, such that the node performing name resolution will be responsible for contacting nodes that are successively closer to the desired PNRP ID. Each iteration works as follows: Once a peer receives a request message, it performs a lookup in its cache for the requested PNRP ID. If a match is found, the request message is sent directly; otherwise, it is sent to the next closest PNRP ID (by seeing how much of the ID matches).
When a node receives a request message for which it cannot find a PNRP ID, it checks the distance of any other IDs in the cache to the target ID. If it finds a node that is closer, the requested node sends a reply to the requesting node, where the reply contains the IPv6 address of the peer that most closely matches the target PNRP ID. The requesting node can then use the IPv6 address to send another query to that address’ node. If no node is closer, the requesting node is notified, and that node sends the request to the next closest node. Assuming PNRP IDs of 200, 350, 450, 500, and 800, Figure 7-32 depicts a possible endpoint determination phase for an example in which peer A is trying to find the endpoint for PNRP 800 (peer E).
To publish its PNRP ID(s), a peer first sends PNRP publication messages to its closest neighbors (entries in its cache that have IDs that are in the lowest levels) to seed their caches. It then randomly chooses nodes in the cloud that are not neighbors and sends them PNRP name resolution requests for its own PNRP ID. Through a mechanism described earlier, the endpoint determination phase results in the seeding of the PNRP ID across the caches of the random nodes that were chosen in the cloud.
Location and Topology
Today, networked computers often move between networks that require different configuration settings—for example, a corporate LAN and a home-based wireless network. Windows includes the Network Location Awareness (NLA) service to enable the dynamic configuration of network applications and settings based on location, and Link-Layer Topology Discovery (LLTD) to enable the intelligent discovery and mapping of networked devices.
Network Location Awareness
Вильям Л Саймон , Вильям Саймон , Наталья Владимировна Макеева , Нора Робертс , Юрий Викторович Щербатых
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