Throttling Bandwidth

Unanswered Question
Nov 9th, 2009

Hello,

Is there a way to limit the available bandwith on a router to a certain amount of throughput but open it up automatically as needed? Lets say you have a 10Mbps pipe and you want to limit the throughput to 5Mbps on average but if needed it can open up to the full 10Mbps automatically for as long as needed and tehn throttle back. I know the first thing that jumps out at me is just to let the full 10Mbps rip at all times but we are trying to move a service provider funtion of a burstable service down to the CPE level. I'm probably not explainging it well. Please feel free to ask clarufying questions.

Thanks in advance. All replies rated

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simontibbitts Mon, 11/09/2009 - 12:21

Hello.

It is not that clear from your description why you want this. You are right, why don't you just allow the full 10Mb? When do you want the bandwidth to automatically throttle back? After a certain amount of traffic? Or do you want it that traffic that exceeds the 5Mbps limit is still allowed but is marked down so it gets a worse QoS value?

If either of these are desired then policing will be what you need. You can read more here:

http://www.cisco.com/en/US/docs/ios/qos/configuration/guide/polcing_shping_oview_ps6350_TSD_Products_Configuration_Guide_Chapter.html

Kind Regards,

Simon

Joseph W. Doherty Mon, 11/09/2009 - 12:41

Is this for some kind of tier bandwidth utilization pricing? I.e. you pay extra for exceeding x bandwidth, but you're willing to use it if you really need too.

Unsure there is a technology that handles such on a single link. I believe OER/PfR can recognize tier bandwidths costs, but it might only come into play if there are multipe paths. (NB: Something clever might be done with GRE tunnels on a single link.) I also recall some of the old channel bonding techniques might allocate channels based on actual bandwidth utilized (e.g. primary ISDN), but don't know if anything similar for single link.

If your concern is only for a relatively short term, peak shaping or peak policing might work. Either could allow a 10 Mbps burst for some time period and then clamp down to 5 Mbps. This though, isn't exactly what you described (although is more like burstable SP bandwidth).

angel-moon Mon, 11/09/2009 - 15:35

Thnkas guys. We are indeed trying to emulate a burstable SP solution. Maybe the better way to go is to leave it at 10Mbps but then do some monitoring and reporting as to when the BW exceeds the 5Mbps cap. Thoughts on that?

Joseph W. Doherty Mon, 11/09/2009 - 17:29

If you want to emulate a burstable SP solution, the PIR policing or shaper should do (starts at 10 than clamps down to 5 Mbps). However, what you otherwise described (caps at 5 Mbps until at some threshold it ramps up to 10 Mbps and then returns to 10 Mbps) is a bit different. Which do you want, the SP solution or the one you've otherwise described?

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