Blockchain is a amazing technology used to store transaction over time while facilitating uniformed trust, integrity and availability to nodes. At a granular level the blockchain consists of transactions aligned in blocks after valid verification by miners forming a web of mathematical trust amongst the nodes involved. All blockchains have configuration parameters like block size and block generation time. Block generation time can have minor variations and block-size overtime can be by tweeked to increase overtime as it is a point of consensus amongst nodes. Like in case of bitcoin blockchain the size of block gradually increased from 256 kb to 1 MB, [Currently 10 MB block size is in heated debate.].

Blockchains chain block size has a interesting network bandwidth linkage, Which requires consideration from the designer and makers, while deciding the building blocks for the blockchains. To precisely arrange the logical pieces in place lets assume we had a blockchain generating blocks every 1 Sec with a size cap of 0.5 MB handling, also assuming blockchains is currently operating at 100% capacity (i.e. - Block size is utilised 100% and most of the blocks generated are roughly about 0.5 MB in size). In order make such a blockchain work a dedicated download speed of 0.5MB is required (i.e. - 4 Mbps of bandwidths is required dedicatedly) for the node to be in sync with the current blockchain. There by rendering nodes with lower bandwidth in a constantly out of sync.

The bitcoin blockchain has 10 Minutes block generation time and 1 MB block size but is facing pressure on increasing the block size since current capacity of 1 MB block is being reached and proposals of 10 MB block are in place. Going back to our issue of dedicated network requirement to keep the node in sync with the blockchain, the block size of 1 MB requires 13.65Kbits / sec bandwidth and with increase in block size to 10 MB would required 136.6 Kbits /sec internet speed. Network bandwidth is not a issue in most part of the world but is defiantly problem in remote parts of the world, where internet services have not penetrated considerably and internet speeds are lagging behind the world average bandwidth. [Currently world average bandwidth is 3.9 MBits / sec based on Akamai state of the internet report 2014.]. Due to the dedicated network requirement a network infeasibility zone for a blockchains is created within current internet architecture. Thus while developing a blockchain or amending it the network infeasibility needs to be taken into due consideration.

The evolution of blockchain is very interesting and fascinating. In the future course it might be possible that blockchains put a pressure on the overall state of information networks across all countries to improve connectivity due to it very capability of becoming the backbone for value transfer across internet :)