[e2e] TCP Performance with Traffic Policing

Barry Constantine Barry.Constantine at jdsu.com
Fri Aug 19 07:09:41 PDT 2011

It's standard Cisco policer from a carrier grade, Metro Ethernet switch (ME3400).  

A quip from the command reference guide:  "The ME-3400E switch supports 1-rate, 2-color ingress policing and 2-rate, 3-color policing for individual or aggregate policing."

Again, my whole intention is to educate network providers that policing can do bad, bad things to TCP performance.

Today, network providers only run UDP traffic through the network to "commission" a service and then they turn on business customer services and then the finger pointing start.

So I performed the OS test in a controlled lab to demonstrate just how badly TCP can be effected by a standard Cisco policer.


-----Original Message-----
From: end2end-interest-bounces at postel.org [mailto:end2end-interest-bounces at postel.org] On Behalf Of Detlef Bosau
Sent: Friday, August 19, 2011 9:29 AM
To: end2end-interest at postel.org
Subject: Re: [e2e] TCP Performance with Traffic Policing

On 08/12/2011 09:37 PM, Barry Constantine wrote:
> Hi,
> Let me provide better background information.
> End-customers (business companies) purchase a network service from a network provider and purchase a Service Level Agreement (SLA).  This SLA specifies the committed information rate (CIR) which the provider will guarantee along with loss / latency specifications.

That's in fact the traditional scenario of, e.g., a Frame Relay link as 
it is done for years now.

Once again my question: How is traffic policing achieved here?

> The end customer connects up either with 100M or 1G interface (generally) and the provider generally polices down to the CIR.

Not quite. CIR means particularly: the _least_ information rate.

That's the reason why I ask for the policing algorithm.

I'm particularly afraid that the algorithm in use may cause a lot of 
packet order distortion.

Detlef Bosau
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