Latency and Privacy in Lightning

The process of syncing a bitcoind node on a MacBook reveals interesting insights into how data packets are handled over the internet, particularly concerning their size. During this operation, it was observed through Wireshark that packets exceeding 1500 bytes were both fragmented and reassembled, specifically pointing out the handling of headers messages. This practice underscores the significance of the Maximum Transmission Unit (MTU) in network communications, which can be identified on any machine by running commands like ifconfig. The MTU dictates the largest size a packet can be for transmission over the network, with 1500 bytes being a common standard.

This standard is not arbitrary but rooted in historical development and technological constraints, as detailed in the article How 1500 bytes became the MTU of the internet. Despite the evolution of internet technologies, the 1500-byte limit has remained largely consistent across different operating systems, hinting at its foundational role in network communication. However, it's important to note that the actual usable payload size for data transmission is somewhat less than 1500 bytes. After accounting for the overhead introduced by the IPv4 or IPv6 header and the TCP header, the effective payload space falls between 1400 to 1460 bytes. These headers consume a significant portion of the packet, thus reducing the space available for actual data.

Understanding these limitations and their implications is crucial for optimizing network performance and ensuring efficient data transmission. The observation of packet fragmentation and reassembly above the 1500-byte threshold also raises considerations for network hardware and protocols, as each router in the path must support handling packets larger than the MTU.