The Ethereum (ETH) Istanbul hard fork was successfully deployed Saturday evening, with Sparkpool being the first pool to mine an Istanbul block. Less than 15 hours before the fork only 53% of Parity and Geth nodes had upgraded to Istanbul, but shortly after the fork, 96.7% of nodes had upgraded to Istanbul, making this a relatively successful hard fork.

Istanbul has brought several changes to the Ethereum (ETH) network, via the Ethereum Improvement Proposals (EIPs) 152, 1108, 1344, 1884, 2028, and 2200.

EIP 152 makes it so that the Ethereum Virtual Machine (EVM) is interoperable with Zcash (ZEC) and other equihash cryptocurrencies. Essentially, this EIP makes it so that Ethereum (ETH) and Zcash (ZEC) are interoperable, giving Ethereum (ETH) users the option to conduct stealth transactions via Zcash (ZEC) technology, and now Zcash (ZEC) users can develop dApps and smart contracts with Ethereum (ETH) technology.

EIP 1108 reduces the gas costs of SNARKs and STARKs, which can have benefits for privacy and scaling solutions. EIP 2028 reduces the cost of zk-SNARK and zk-STARK smart contracts, which will increase the network bandwidth of Plasma, which is an Ethereum (ETH) layer 2 solution.

EIP 1884 reduces the gas costs of certain computationally intensive EVM operations, and reduces the potential of spam attacks while simultaneously creating a more optimal gas/resource consumption balance. EIP 2200 changes storage cost calculations in the EVM, facilitating the introduction of new functions in some smart contracts.

Finally, EIP 1334 prevents transaction replay attacks via implementing a chain ID system.

Thus, the Istanbul hard fork and its associated EIPs increase the scalability of the Ethereum (ETH) network via reducing gas costs and paving the way for layer 2 solutions. It simultaneously increases security by preventing transaction replay attacks and spam attacks, and also increases anonymity on the Ethereum (ETH) network via interoperability with Zcash (ZEC).

Overall the Istanbul hard fork received a positive reception since the upgrades were beneficial and not controversial. No changes to Ethereum (ETH) mining occurred in the Istanbul hard fork.

However, the difficulty bomb is going off, with block times now exceeding 15 seconds, and another hard fork will be needed soon to prevent the network from slowing to a crawl. Apparently, this hard fork could come in early January and will be called Mountain Glacier.