in π Notes

# Kademlia (DHT)

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Kademlia is one implementation of a Distributed Hash Table.

The **3 parameters**:

**Address space**: a way to uniquely identify all the peers in a network.- A
**metric**to order the peers in the address space and therefore be able to visualize them along an ordered line. - A
**projection**that will take a record key and calculate a position in the address space where the peer(s) most ideally suited to store the record should be near.

More details:

- Peers can join (or leave) at any time hence it’s unstable.
- Each peer keeps links to the peers located at $2n$ of distance.
- For each multiple of 2, each peer keeps up to $K$ links.
- $K$ is determined based on the observed average churn in the network and the frequency with which the network republishes information.
- Computed to maximize the probability of keeping the network connected while maintaining good latency values for queries.

This will:

- Allow to search the network as if it was a sorted list.
- Allows for a lookup time of $O(\log(N))$ where $N$ is the size of the network.

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