Network engineering continued ...

This is a continuation of the earlier posts starting with this one: http://ravinote.blogspot.com/2020/09/best-practice-from-networking.html  

344. A Peer-to-Peer (P2P) network is popular for file-sharing or data sharing activities because the data accrues based on popularity, not on utility.  

345. A P2P network introduces a network first design where peers are autonomous agents and there is a protocol to enable them to negotiate contracts, transfer data, verify the integrity and availability of remote data, and to reward with payments. It provides tools to enable all these interactions. It enables the distribution of the storage of a file as shards on this network and these shards can be stored using a distributed hash table. The shards themselves need not be stored in this hash table, rather a distributed network and messaging could facilitate it with location information. 

346. 351. P2P can be structured or unstructured. 

     352. In a structured topology, the P2P overlay is tightly controlled usually with the help of a distributed hash table (DHT). The location information for the data objects is deterministic as the peers are chosen with identifiers corresponding to the data object's unique key. Content goes to specified locations that make the subsequent query easier. 

     353. Unstructured P2P is composed of peers joining based on some rules and usually without any knowledge of the topology. In this case, the query is broadcast, and peers that have matching content return the data to the originating peer. This is useful for highly replicated items but not appropriate for rare items. In this approach, peers become readily overloaded and the system does not scale when there is a high rate of aggregate queries. 
          P2P is considered a top-heavy network. Top-heavy means we have an inverted pyramid of layers where the bottom layer is the network layer.  This is the substrate that connects different peers.  The overlay nodes management layer handles the management of these peers in terms of routing, location lookup, and resource discovery. The layer on top of this is the features management layer which involves security management, resource management, reliability, and fault resiliency.