An Overview of the Polkadot Blockchain

With the parachain auctions confirmed as imminent, it looks like the Polkadot blockchain could soon have the spotlight more firmly on it. So what exactly sets this blockchain apart and how does it work?

The Network Architecture
The Polkadot network is a function rich blockchain which carries similarities and ambitions like the Ethereum network. This is no surprise since its creator is Dr Gavin Wood, the co-creator of Ethereum, and inventor of the smart contract language Solidity and the Parity Ethereum client.

The network launched in stages with the initial release of phase 1 on May 27th 2020 and phase 2 following on June 18th 2020 (which also saw the network change its consensus model from proof-of-authority to delegated proof-of-stake). Phase 3 and 4 followed in July 2020 and saw the governance layer decentralized to the wider token holders. The final stage was successfully launched on August 18th 2020 which allowed for the native asset DOT to be transferred.

Initially the network had two testnets; Birch and Alexander, however these are no longer active and the testnet for Polkadot is now Rococo. There is also Kusama which is designed as a canary network to test staking, governance and sharding.

The key USPs for Polkadot are a focus on scalability with the introduction of sharding, and interoperability with bridges. Scalability is achieved by having a network of parachains (parallelised chains) which are interoperable with each other and anchor to the Relay Chain —the spine for the network.

This may sound like a familiar model, and it is — it’s the direction of travel for Ethereum which is looking to implement sharding to improve scalability. This is under the banner for the ongoing ETH2.0 work. As such on the Ethereum2.0 network there is a Beacon Chain (=Relay Chain on Polkadot) and there will initially be 64 shards (=parachains on Polkadot).

The Polkadot network aims to initially release 100 parachain slots, available to buy via auction but with a small number being reserved for common good projects. To claim a parachain slot, DOT must be held in bond and can only be retrieved when the lease on the parachain expires or is returned. The parachain owners will be able to use the Substrat application stack native to the Polkadot ecosystem to built smart contract capabilities, decentralized apps (Dapps) and even entire Polkadot-compatible ecosystems. In addition, the introduction of bridges to other established ecosystems such as Ethereum, Bitcoin and Polygon etc will look to enable value (whether via assets or arbitrary data) to be moved across ecosystems with ease and security.

The vision behind the Polkadot network is therefore for the Relay Chain to be a low volume governance chain which supports the correct functioning of many independent but interoperable parachain networks as well as out to other blockchains using bridges.

Roles on the Network

Validators and Nominators: Those who stake DOT on the Relay Chain are able to validate transactions and will receive staking rewards for maintaining the smooth running of the network as a whole. These Validators are nominated by Nominators who will receive a portion of any staking rewards won if the Validator is successfully chosen or who will have their DOT slashed if the Validator misbehaves.

Collators: Another role on the network is Collators who maintain a parachain. Their responsibilities are; maintaining a full-node for their parachain, keeping a record of all necessary information for the parachain, and producing candidate blocks which are sent to the Relay Chain validators for verification. Their reward structure and consensus methods will be determined by the implementation details of the specific parachain, rather than any global Polkadot requirements. Collators do not need to own DOT or be validators on the Relay Chain.

Fishermen: There is then an important role with the creative name of ‘Fisherman’. These network participants monitor the ecosystem for bad behaviour and report anything suspicious or untoward to the validators within special high priority transactions. They must stake a small amount of DOT but can be heavily rewarded for reporting misdemeanours.

Native Asset

The native asset for the Relay Chain is DOT and has a current supply of 1billion with a 10% annual inflation. The smallest denomination is 0.0000000001 and creatively called a Planck after the smallest unit of length in the universe. DOT is used to pay fees, for governance actions, and as a bond for a parachain slot. Whilst it is the only asset on the Relay Chain, parachains can choose to have their own currency so do not need to use or hold DOT to be part of the wider Polkadot ecosystem. However, since the Relay Chain is a proof-of-stake network, then validators must stake DOT in order to be able to confirm blocks of transactions, and Collators must bond dot to claim their parachain slot.

Network Activity

The total transactions per day are less than 15k but growing, and the active accounts per day is also steadily increasing.

The average transactions per block are less than 5, and this compares with around 75–100k total events per day. However the majority of these are governance related and do not move value across the ecosystem.

Block creation is faster than Ethereum’s c10 second and is one block every c6 seconds. Each block has 25% of its capacity reserved for operational transactions such as; misbehaviours reported by Fisherman and governance related actions.