This test shows two TCP connections with different round-trip time. Because of TCP's window increase algorithms the connection with shorter round-trip time increases its window faster and receives a disproportionate share of the link bandwidth.

Expected output:

• The connection with a shorter round trip time will get more packets sent and less packet loss compared to a connection with a longer round trip time.

Test Topology:

 Server ................Router..................Client

        8Mbs 200ms
 5(0)------------------0(1)        800kbs 100ms
                            0(0)-----------------7(0)
 6(0)------------------0(2)
        8Mbs 5ms

send window = receive window  =  30 packets

use drop tail queue at the bottleneck NIC in the router

SSF Tcpdump File:

f10_1.tcpdump

f10_2.tcpdump

NS Test with the random drop queue

NS tcpdump trace file: f10.tr

Trace Analysis:

The output is consistent with expected output.

The difference between the NS trace and SSF trace is caused by the following reason:

An NS TCP connection begins with the first data packet, but SSF TCP connection begins with the 3-way handshake before the first data packet is sent. In this test, the trace pattern is sensitive to the start time of each connection.