The default window size that iPerf uses varies by machine type and operating system. If it’s 64 KBytes, with a modest latency of 10 ms, the maximum bandwidth you can get is 52.43 Mbits/sec. For 50 ms the maximum is 10.49 Mbits/sec.

Mar 03, 2020 TCP streaming workload tuning - IBM The rfc1323 tunable enables the TCP window scaling option. TCP path MTU discovery The TCP path MTU discovery protocol option is enabled by default in AIX. This option allows the protocol stack to determine the minimum MTU size on any network that is currently in the path between two hosts, and is controlled by the tcp_pmtu_discover=1 network How to set the maximum TCP receive window size in Windows As you have already shown, they are in fact one quarter of the default sizes, which historically had been miles too low for decades. A large TCP window is 48k or more. 2k is completely useless. You'd be better off leaving it strictly alone. – Marquis of Lorne Jun 26 '13 at 11:59 Anyway to default the window size - Windows 10 Forums

window_size Specifies the size, in kilobytes, to use for your client node TCP/IP sliding window. The range of values is 0 through 2048. A value of 0 allows Tivoli Storage Manager to use the operating system default TCP window size. Values from 1 to 2048 indicate that the window size is in the range of 1KB to 2MB.

Mar 25, 2020 IPERF and TCP window size - University Jul 08, 2014 Performance Tools for Network Workloads | Microsoft Docs

TCP tuning - Wikipedia

MSS = MTU - size of the TCP header (40 bytes) Note2: It is possible to set a larger initial window size, up to 65535 bytes. The value can be 65160 if the maximum size of receive buffer is set to 67108864 (64MB) or larger and other values are kept unchanged. For more information about the initial window size, refer to RFC 3390 and When tcp tcp(7) - Linux manual page The default value is calculated using the formula max(65536, min(4 MB, tcp_mem[1]*PAGE_SIZE/128)) (On Linux 2.4, the default value is 128 kB, lowered 64 kB depending on low-memory systems.) tcp_workaround_signed_windows (Boolean; default: disabled; since Linux 2.6.26) If enabled, assume that no receipt of a window-scaling option means that the TCP Windows and Window Scaling -