Supernodes are high performance blockchain nodes which form the backbone of the NEM blockchain network. Accounts with 3,000,000 or more XEM can operate a supernode, either from a local computer or from a cloud-hosted server. Supernodes are required to be up and running 24 hours per day, processing all transactions.
The NEM network has two layers. The supernode layer keeps the system powerful and fast, whilst ensuring that it maintains efficiency and optimum performance. This layered design allows the second layer of wallets and third party apps to use the entire network without downloading or processing the entire blockchain.
Supernode accounts are required to hold at least 3,000,000 XEM, and are tested 4 times per day on their bandwidth, chain height, chain parts, computing power, version, ping and responsiveness to make sure that they are performing the highest standards.
|Bandwidth||5,000 kbit/s or higher.||2MB downloads averaged from 3 nodes.|
|Chain Height||Chain must be synced.||No more than 4 blocks behind the reference NIS.|
|Chain Part||Upload 50 block sections of the chain accurately||Hashes of the download are compared to the reference chain for accuracy.|
|Computing Power||Hash at least 2000 iterations per second.||Node is asked to calculate 10.000 iterations of a 32 byte seed. Speed and final accuracy are measured.|
|Banded Deposit||3,000,000 XEM.||Node must be booted with the delegate key of an account with the deposit.|
|NIS Version||NIS must be up to date.||Admins should update nodes in a timely manner.|
|Ping||200ms response or less.||Ping times for every other node are collected and at least one ping time must pass the test.|
|Responsiveness||A node has to answer 10 consecutive blockchain height requests.||THe node passes the test if the overall time needed to answer at least 9 requests is at most 1 second.|
The development team maintains the right to change any of these requirements as needed to keep the number and performance of supernodes at optimum levels.
Proof of Importance (POI) is the algorithm that determines how likely each account is to complete a block and earn all the transaction fees contained in it. Supernodes have the ability to host non-supernode harvesting accounts. This is called Delegated Harvesting and it has a double benefit. Harvesting accounts lend their POI score to the supernode’s POI, increasing its chance of completing a block. When a supernode completes a block because it was using a harvesting account’s POI score, the harvesting account keeps the transaction fees.
POI Score Depends on 3 Factors:
This lets any harvesting account collect transaction fees, closely similar to mining coins in other cryptocurrencies, but with no special hardware required, low energy usage, and with an incentive to make transactions instead of hoarding coins.
You can read more about Delegated Harvesting here, including how to set up your wallet and connect to someone else’s supernode.