Distributed hash table

Navigation menu

GetRight and BitTorrent's DHT Network
Some thanks for help with this One drawback is that, like Freenet, DHTs only directly support exact-match search, rather than keyword search, although Freenet's routing algorithm can be generalized to any key type where a closeness operation can be defined. Distributed Hash Table Network. Sign up or log in Sign up using Google. I am going to edit this post later tonight and explain why, unless someone else does before that The time now is

Using DHT tracker

A free C++ BitTorrent/HTTP/FTP Download Client

The two algorithms appear to have been devised independently and simultaneously to solve the distributed hash table problem. Both consistent hashing and rendezvous hashing have the essential property that removal or addition of one node changes only the set of keys owned by the nodes with adjacent IDs, and leaves all other nodes unaffected.

Contrast this with a traditional hash table in which addition or removal of one bucket causes nearly the entire keyspace to be remapped. Since any change in ownership typically corresponds to bandwidth -intensive movement of objects stored in the DHT from one node to another, minimizing such reorganization is required to efficiently support high rates of churn node arrival and failure. Each node is assigned a single key called its identifier ID. Thus, the circular keyspace is split into contiguous segments whose endpoints are the node identifiers.

In rendezvous hashing , also called highest random weight hashing, all clients use the same hash function h chosen ahead of time to associate a key to one of the n available servers. The client associates that key with the server corresponding to the highest hash weight for that key.

Locality-preserving hashing ensures that similar keys are assigned to similar objects. This can enable a more efficient execution of range queries. Self-Chord [11] decouples object keys from peer IDs and sorts keys along the ring with a statistical approach based on the swarm intelligence paradigm.

Sorting ensures that similar keys are stored by neighbour nodes and that discovery procedures, including range queries, can be performed in logarithmic time. Each node maintains a set of links to other nodes its neighbors or routing table. Together, these links form the overlay network. A node picks its neighbors according to a certain structure, called the network's topology. All DHT topologies share some variant of the most essential property: It is then easy to route a message to the owner of any key k using the following greedy algorithm that is not necessarily globally optimal: When there is no such neighbor, then we must have arrived at the closest node, which is the owner of k as defined above.

This style of routing is sometimes called key-based routing. Beyond basic routing correctness, two important constraints on the topology are to guarantee that the maximum number of hops in any route route length is low, so that requests complete quickly; and that the maximum number of neighbors of any node maximum node degree is low, so that maintenance overhead is not excessive.

Of course, having shorter routes requires higher maximum degree. Some common choices for maximum degree and route length are as follows, where n is the number of nodes in the DHT, using Big O notation:. Many DHTs use that flexibility to pick neighbors that are close in terms of latency in the physical underlying network.

Maximum route length is closely related to diameter: Route length can be greater than diameter, since the greedy routing algorithm may not find shortest paths.

Aside from routing, there exist many algorithms that exploit the structure of the overlay network for sending a message to all nodes, or a subset of nodes, in a DHT. Or even more fun is Six Degrees of Kevin Bacon , doing the same with actors in films.

The DHT Network lets computers do that. After repeating the process a few times, you'll find the peer with the information you need. What does this do for me? A regular BitTorrent download has a central server computer that helps coordinate all the people downloading, helping them find each other, etc. With the DHT Network, no central server computer is needed, people downloading Torrents all help each other track who is downloading the same file you are.

What information is sent when doing this? The information that is sent: Your IP address and port. This is required and lets other computers know where you are, and how they can contact you.

Is it possible to find a torrent in DHT network without knowing its hash? Even using DHT one peer has to have a torrent file for some information otherwise no one could find it, By searching for file names could give results, so always make your folder and file names generic goop of letters and numbers before distribution. Then you have to send. Sign up or log in Sign up using Google.

Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.

Your Answer