[e2e] TCP Performance with Traffic Policing

[Barry Constantine]

Hi,

I did some testing to compare various TCP stack behaviors in the midst of traffic policing.

It is common practice for a network provider to police traffic to a subscriber level agreement (SLA).

In the iperf testing I conducted, the following set-up was used:

Client -> Delay (50ms RTT) -> Cisco (with 10M Policing) -> Server

The delay was induced using hardware base commercial gear.

50 msec RTT and bottleneck bandwidth = 10 Mbps, so BDP was 62,000 bytes.

Ran Linux, Windows XP, and Windows 7 clients at 32k, 64k, 128k window (knowing that policing would
kick in at 64K)

               Throughput for Window (Mbps)

Platform              32K        64K        128K
--------------------------------------------
Linux                     4.9         7.5         3.8
XP                          5.8         6.6         5.2
Win7                     5.3         3.4         0.44


Do anyone have experience with the intricacies of the various OSes in the midst of
Traffic policing?  I was surprised to see such a variation in performance, especially since Windows 7 is supposed to more advanced than XP,

I am going to comb through the packet captures, but wondered if anyone had insight.

Thank you,
Barry

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