Factors limiting bandwidth

This page calculates the theoretical maximum TCP throughput based on the specified parameters. You are unlikely to achieve this speed in the real-world due to other protocol overheads and competing traffic.

Based on window sizes:

RTT ("ping")		ms
Window size		Bytes
Minimum Window Scale	0	Bits
Bandwidth delay product (BDP)	1,051.20	Byte seconds
Maximum tcp download bandwidth	292,000.00	Bytes/s
	2,336,000.00	Bits/s
	200.00	Packets/s

Based on packet loss (TFRC)

Delayed acks		Count
MSS		Bytes
Bytes/ack	2,920.00	Bytes/ack
RTT	60.00	ms
RTO	240.00	ms
Delayed Acks	2	acks
Packet loss		%
Maximum tcp download bandwidth	660,451.52	Bytes/s
	5,283,612.19	Bits/s
	452.36	Packets/s

Based on upstream ack bandwidth:

Upstream bandwidth		Bits/s
Upstream bandwidth	16,000.00	Bytes/s
ACK size		Bytes
ACKs/s	400.00	packets/s
Maximum tcp download bandwidth	1,168,000.00	Bytes/s
	9,344,000.00	Bits/s
	800.00	Packets/s

Limit (based on all the above)

Maximum tcp download bandwidth	292,000.00	Bytes/s
	2,336,000.00	Bits/s
	200.00	Packets/s
Limit reason	Window Size

Notes:

Windows uses 40 byte acks, Linux 52. if ethernet is run on the slowest link, the minimum size for an ack becomes 46 bytes. (ethernet has a 60 byte minimum packet size, and a 14 byte header)
You'll NOT get the theoretical maximum throughput as limited by upstream bandwidth, as this assumes one tcp connection under perfect conditions. Multiple connections will be slower
Linespeeds are often serialisation rate, over the top of that you have framing, FEC, and other crap. What bandwidth you'll actually recieve is not obvious.
Most hosts send delayed acks every 2 acks, some every ack (1). When dealing with massively assymetric links, hacking your stack to support 3 would seem to be the best solution (and it's a reciever solution, not a sender one too as an added bonus)
Default Window sizes for various OS versions

Windows 98 8192

Windows 2000 17520

Linux 262,144

FreeBSD 65535

Windows XP* 17520

MSDN** 8760

* windows XP apparently has some undocumented way of selecting this
** This uses the algorithm from an MSDN article which seems waay too low.
Windows size limited downloads are limits per TCP connection, so P2P apps can exceed this limit.
windows 2000+ and linux can both have windows larger than 64k, 98 can't,
MSDN article including the selected window size for windows 2003
How to tweak your window sizes
Throughput calculation formula
RFC3448: TCP Friendly Rate Control (TFRC): Protocol Specification. -- Formula used for Throughput under packet loss.