Re: QOS - bandwidth, shape, police

Hi Mark,
If you explain the difference to the three techniques you should be able to
pick the right one based on the task wording. Here's a brief summary:

The bandwidth is used in case of congestion on a interface. So when there's
no congestion, there's no problem and the class can use more then the
bandwidth configured.
Policing is done inbound usually, (it can also be done outbound) and is a
non-friendly way of committing to the configured cir. As it drops, it doesnt
queue!
Shaping is done outbound, and uses queueing. If the queue if full it will
drop based on WRED or whatever congestion avoidance you configure.

So when you have a 100Mb/s connection to your ISP (based on FastEthernet)
and you pay for 10Mb/s. The ISP will police you inbound on their side. And
you have to make sure you adhere to the 10Mb/s outbound so your traffic is
not dropped the 'hard' way by your isp. :)

Hope this helps!
Wouter

2009/9/8 Mark Matters <markccie_at_gmail.com>

> I am starting to confuse myself on when to use bandwidth, police or shape.
>
> Based on question wording who do you know what they are asking you to do?
>
> Am I right here?
> Bandwidth = guaranteed bandwidth
> Police = maximum bandwidth
> Shape = limit bandwidth
>
>
>
> R411(config-pmap)#class thisisgoingtodrivemetodrink
> R411(config-pmap-c)#?
> QoS policy-map class configuration commands:
> bandwidth Bandwidth
> compression Activate Compression
> drop Drop all packets
> exit Exit from QoS class action configuration mode
> netflow-sampler NetFlow action
> no Negate or set default values of a command
> police Police
> priority Strict Scheduling Priority for this Class
> queue-limit Queue Max Threshold for Tail Drop
> random-detect Enable Random Early Detection as drop policy
> service-policy Configure Flow Next
> set Set QoS values
> shape Traffic Shaping
>
>
>
>
> R411(config-pmap-c)#bandwidth ?
> <8-2000000> Kilo Bits per second
> percent % of total Bandwidth
> remaining % of the remaining bandwidth
>
>
>
> R411(config-pmap-c)#police ?
> <8000-2000000000> Bits per second
> cir Committed information rate
> rate Specify police rate
>
>
> R411(config-pmap-c)#shape ?
> adaptive Enable Traffic Shaping adaptation to BECN
> average configure token bucket: CIR (bps) [Bc (bits) [Be (bits)]],
> send out Bc only per interval
> fecn-adapt Enable Traffic Shaping reflection of FECN as BECN
> fr-voice-adapt Enable rate adjustment depending on voice presence
> max-buffers Set Maximum Buffer Limit
> peak configure token bucket: CIR (bps) [Bc (bits) [Be (bits)]],
> send out Bc+Be per interval
>
> --
>
>
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-- 
Wouter Prins
wp_at_null0.nl
0x301FA912
Blogs and organic groups at http://www.ccie.net