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Configuring traffic shaping / policing for Dynamic Port

Our WAN link service provider is pushing us to migrate all of our remote WAN links to what they call Dynamic Port.  Currently most of my remote sites are on 512k circuits (115 / 122).  The rest are T1 or bigger.  The process to migrate them is to upgrade all remote sites to full T1 bandwidth.  Then we use a website to initiate an order to lower them back down to the bandwidth we want.  Now this is where my questions kick in.

If my service provider lowers my port speed on their side, but I do nothing on my router and it still thinks it has a full T1 connection, then I think it will still send out at full T1 speeds.  Then my service provider becomes the policeman and either drops my packets or allows them through and charges for overusage.

My service provider told me that just putting a bandwidth xxx command on the serial interface will limit my bandwidth, but I thought that command was just for routing decisions, not physical bandwidth.

I'm looking for pros / cons on using either traffic shaping vs. policing on my remote routers to keep them at the CIR we set on the service provider website.  Is anyone else using this, and what were your solutions?


Cisco Employee

Re: Configuring traffic shaping / policing for Dynamic Port

The solution you are alluding to is the best practice.  It's called hierarchical qos.  You'll have a parent shaper at the rate you have negotiated with the ISP, which allows you to control how packets get prioritized within the child policy.

this document has a configuration example:

Router(config)# policy-map CHILD
Router(config-pmap)# class VOICE
Router(config-pmap-c)# priority 1000
Router(config-pmap-c)# class MCA
Router(config-pmap-c)# bandwidth 2000
Router(config-pmap-c)# class VIDEO
Router(config-pmap-c)# bandwidth 5000
Router(config)# policy-map PARENT
Router(config-pmap)# class class-default
Router(config-pmap-c)# shape average 10000000
Router(config-pmap-c)# service-policy CHILD

Hope that helps.

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