$ sudo ip link set mtu 6128 dev eth0

$ nuttcp -v $SMALLER_HOST
nuttcp-t: v6.1.2: socket
nuttcp-t: buflen=65536, nstream=1, port=5001 tcp -> $SMALLER_HOST
nuttcp-t: time limit = 10.00 seconds
nuttcp-t: connect to $SMALLER_HOST with mss=6076, RTT=0.412 ms
nuttcp-t: send window size = 168960, receive window size = 222592
nuttcp-t: available send window = 84480, available receive window = 111296
nuttcp-t: 539.0589 MB in 10.00 real seconds = 55199.38 KB/sec = 452.1933 Mbps
nuttcp-t: retrans = 0
nuttcp-t: 8625 I/O calls, msec/call = 1.19, calls/sec = 862.50
nuttcp-t: 0.0user 0.5sys 0:10real 5% 0i+0d 992maxrss 0+0pf 6039+7csw

nuttcp-r: v6.1.2: socket
nuttcp-r: buflen=65536, nstream=1, port=5001 tcp
nuttcp-r: accept from $SMALLER_HOST 
nuttcp-r: send window size = 168960, receive window size = 222976
nuttcp-r: available send window = 84480, available receive window = 111488
nuttcp-r: 539.0589 MB in 10.04 real seconds = 54969.76 KB/sec = 450.3122 Mbps
nuttcp-r: 47036 I/O calls, msec/call = 0.22, calls/sec = 4684.01
nuttcp-r: 0.0user 0.9sys 0:10real 10% 0i+0d 690maxrss 0+15pf 38414+166csw