mrnx/network

Bandwidth & throughput

Measure a running copy from two dir snapshots, estimate transfer times and required link speed, and check whether the TCP window or latency is the real bottleneck.

Live transfer progress

Paste dir flash: | include .bin twice, a few seconds apart

Each box is timestamped when you paste into it. A plain byte count works too. This only works when the file grows in flash during the copy; if the size stays the same between snapshots, the switch is buffering it elsewhere.

Transfer time

Required bandwidth

TCP window & latency

One TCP stream: throughput by round-trip time

Hover to read any round-trip time; click, drag or use the arrow keys on the marker to set it.

A single TCP stream can never go faster than window ÷ RTT. To fill the link, the window must be at least the bandwidth-delay product (BDP). Without window scaling (RFC 7323) the window tops out at 64 KiB.

Data units

Disks are sold in decimal units (1 TB = 1012 bytes); operating systems often show binary units (TiB), which is why a "1 TB" disk shows as 931 GB.

Latency from distance

From Brussels, approx.

Light in fibre covers about 204 km per millisecond. Real round-trip times are higher: routers, queues and detours add to this floor, so anything far below it means the path is shorter than you think.

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