QOS basic

[Hari Vishnu]

  Hi,

Can any one please describe the live scenarios on which we have to  choose traffic policing over Traffic Shaping ?

Thanks,

[John Blakley]

Traffic shaping is used outbound to control speed. You'd want to configure this one both ends that you control. Policing can be used on inbound or outbound, and generally it's used to control inbound traffic.

I have a policy to control servers that push traffic to workstations inbound, so I have policing set up, but outbound I control it with shaping policies.

ISPs will police traffic inbound. For example, if you have an ethernet circuit, the physical line speed is 100Mb. You may only have a 20Mb circuit, so the ISP will put a policing policy inbound for a cir of 20Mb. You should shape outbound at 20Mb instead of letting the 100Mb hit the ISP to only have it dropped. It's always best practive to shape to the speed of the circuit that you have if your physical media can run faster than your cir.

HTH,

John

[Joseph W. Doherty]

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Posting

One good reason to use policing vs. shaping if you just want to mark traffic based on its bandwidth consumption.

Otherwise, generally policing is used when shaping is not available, as in John's mention of ingress policing.