Microsoft Technology Licensing, LLC

Other

John L Miller

Alexandru Gavrilescu

Christos Gkantsidis

Graham Arthur Wheeler

Rohit Gupta

Manuel Costa

Christian F Huitema

Pablo Rodriguez Rodriguez

Stuart Ranson

Anders Edgar Klemets

Aamer Hydrie

Rebecca Claire Weiss

Sandeep Singhal

Noah Horton

Brian R Lieuallen

Armando Garcia-Mendoza

Christina Huitema

Ravi Rao

Michael John Conrad

Scott A Senkeresty

Pablo Rodriguez

Grigori M Somin

Radu Simionescu

Michael Shappell

Diana Anca Carutasu

Sarat C Manni

Henry Rawas

A method is provided for a host node in a computer network to determine its coordinates in a d-dimensional network space, comprising discovering an address of a peer node in the network, measuring network latency between the host node and the peer node, determining whether network latency has been measured for at least d+1 peer nodes, where, if network latency has not been measured for at least d+1 peer nodes, estimating the network coordinates of the host node, and where, if network latency has been measured for at least d+1 peer nodes, calculating the network coordinates of the host node using d+1 measured latencies.

System and method for implementing PNRP locality

The invention provides methods of encoding content for distribution over a network and methods for decoding encoded content which has been distributed over the network. In a first example in which the content is divided into a plurality of segments and each segment comprising a plurality of blocks of data, the method comprises selecting a segment from the plurality of segments and selecting at least two blocks of the selected segment from a store of blocks. A new encoded block is created from a linear combination of the selected blocks.

Encoding and decoding optimisations

In a typical peer-to-peer network, any user of the peer-to-peer network may request a lookup of a key and its associated value. To limit access to a stored key-value pair, a user node may generate a registration message for a key-value pair. The value may include the payload to be stored at the storage node, and an access list containing one or more retrieval identifiers indicating one or more users authorized to access the payload. In some cases, the registration message may also include an encrypted payload which is encrypted with a group key. The group key may be included in the registration message, and may be encrypted with an encryption key which is known by the authorized user.

Peer-to-peer network communication

A topology management process is implemented in peer-to-peer content distribution clouds using tracker nodes. Tracker nodes have information about available peers and assist peers in finding other peers to connect to. Various algorithms for use at the tracker nodes are described for selecting which peers to return as potentials for forming connections to. In addition, architectures and algorithms to allow efficient scaling of tracker nodes in peer-to-peer clouds are described.

Topology management in peer-to-peer content distribution clouds

The invention describes a control node for a content distribution network and a method of automatically verifying content distributed over a network at a node in the network. In the method, a content description is received which comprises a content identifier, a publisher identifier, publisher authorization information and content checking information. The integrity and validity of this information are checked and if both the checks are passed, the content description is stored.

Secure content descriptions

Managing content by influencing its distribution in the form of blocks or other units is crucial to the performance of a peer-to-peer content distribution system. We provide a content management module at each peer node to achieve this. The content management module implements a content request/response cycle in order to negotiate about blocks of content with other peer nodes. This cycle comprises an offer request, offer reply and a block request. These steps are preferably followed by data exchange and verification. The negotiation protocol used by our content management module provides a generic method that is advantageously used in conjunction with different encoding schemes such as full network coding and group network coding. In one embodiment we use group network coding and add information to the offer request and offer reply to facilitate efficient content distribution. Block request messages are selected to promote the use of on-the-fly decoding where possible.

Content management in peer-to-peer content distribution clouds

A serverless name resolution protocol ensures convergence despite the size of the network, without requiring an ever-increasing cache and with a reasonable numbers of hops. This convergence is ensured through a multi-level cache and a proactive cache initialization strategy. The multi-level cache is built based on a circular number space. Each level contains information from different levels of slivers of the circular space. A mechanism is included to add a level to the multi-level cache when the node determines that the last level is full. A peer-to-peer name resolution protocol (PNRP) includes a mechanism to allow resolution of names which are mapped onto the circular number space through a hash function. Further, the PNRP may also operate with the domain name system by providing each node with an identification consisting of a domain name service (DNS) component and a unique number.

Peer-to-peer name resolution protocol (PNRP) and multilevel cache for use therewith

A wire protocol is described which implements connection management and other methods to give enhanced peer-to-peer content distribution. Connections between nodes can be placed in a 'notify' state when they are idle but may soon yield useful content. This notify state is also used together with a content request/response cycle to allow a peer to evaluate content available at a neighbour. If no suitable content is available a notify state is entered. When new content is later received at the neighbour it is able to inform the requesting node to allow it to restart the content request/response cycle.

Peer-to-peer message format data structure

A topology management process is implemented which involves removing or 'tearing down' connections between nodes in certain situations in order to try to replace those connections with more optimal ones. Idle connections are torn down unless those are in a 'notify' state; a notify state being one in which a request for content has been made to a neighbour but that neighbour has no available content as yet. Idle connections in a notify state are torn down only if they remain idle for a longer time than that required before an idle connection is torn down. To avoid problems caused by clusters of node forming and of loners being unable to join the cloud, network churn algorithms are taught. These involve requiring nodes to drop connections when specified conditions are met. Relative content distribution between connections is monitored and this information used to influence selection of those connections to drop.

Connection management in peer-to-peer content distribution clouds

In a typical peer-to-peer network, any user of the peer-to-peer network may request a lookup of a key and its associated value. To limit access to a stored key-value pair, a user node may register a key-value pair in a peer-to-peer network associated with an access list listing those user nodes which are authorized to access the key-value pair. The access list may include one or more retrieval identifiers. To further secure the information, the retrieval identifiers and/or the payload may be encrypted. To allow the retrieving user to decrypt an encrypted payload, the payload may be encrypted using a group key associated with the stored key-value pair. The group key may be encrypted using a key known to the retrieving user.

Peer-to-peer network information storage

In a distributed hash table (DHT), a participating node has a routing cache associating nodes in the DHT with their respective network addresses. Messages can be routed with the routing table using prefix-matching or numerical-closeness without requiring rigid structuring of the node's cache. Entries in the cache may be replaced using routing information obtained from en route messages. Entries in the routing cache may be replaced without regard for the nodeIDs in or entering the routing cache, and/or without structuring the routing cache according to the nodeIDs placed therein. Cache entries may be replaced randomly.

Routing cache for distributed hash tables

A security infrastructure and methods are presented that inhibit the ability of a malicious node from disrupting the normal operations of a peer-to-peer network. The methods of the invention allow both secure and insecure identities to be used by nodes by making them self-verifying. When necessary or opportunistic, ID ownership is validated by piggybacking the validation on existing messages. The probability of connecting initially to a malicious node is reduced by randomly selecting to which node to connect. Further, information from malicious nodes is identified and can be disregarded by maintaining information about prior communications that will require a future response. Denial of service attacks are inhibited by allowing the node to disregard requests when its resource utilization exceeds a predetermined limit. The ability for a malicious node to remove a valid node is reduced by requiring that revocation certificates be signed by the node to be removed.

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Cambridge, United Kingdom

John L Miller