Need help in Applying QOS to an ISP on ASR 1002

Question

Hi
i want to ask 
if someone gave me CIR with 900Mbps internet upload & download
the question is being asked is.
when the congestion occurs ( when my bw is full)
where does the congestion occur ??
on my router ?
or ISP router ?
or the internet ?
or other place ???
that issue is deiving me mad , because im doing qos on my side to guarantee bw and shape  but it dont give me a result ?!
i mean , the qos is maching ok and soo nice
but ..... the performance.
agian
the performance as there is no guarantee and no bw guaranteed.
i asked an expert and told me you have to ask  your provider to do that thier side ?!!!  im really shocked to hear that ... he told me that congestion occurs outside my router.
so , im here to ask agian and agian.
what choices i have to fix my issue ??
wish to help
regards

Answer 1

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Posting
At "big speeds", there's a difference between shaping and policing.  However, generally within an ISP, policing is used to restrict bandwidth usage, of a customer, to some agreed upon CIR (when CIR is less than physical capacity).  With policing you don't need to manage any generated congestion (as over rate packets are just discarded).  Policing is also "lightweight" in its resource demands and is often directly supported by the hardware.
I do agree ISPs, that provide SLAs, avoid over subscription because otherwise SLAs might not be meet.  However, if SLAs are not provided, over subscription isn't uncommon.  If too much of the latter is done, customers may indeed change ISPs, but do they have a choice?  Or, how do the different ISP fees compare?  (ISPs do analyze customer impact, i.e. customer retention, with cost of providing the service.  They try to determine what's most profitable, not what the customer would like most.  [Do you have gig to your home yet?  If not, why not?  Is it because it cannot be technically done, or is cost and/or what other ISPs offer in the area a factor? (If you're lucky, maybe you have Google fiber, but even that might be a "loss leader".)])
BTW, at "big speeds", another reason shaping is avoided, and also why over subscription is avoided, is because of the needed queuing.  For example, say you wanted to queue up to 100 ms of traffic.  Well on a 100 Gbps link, that's 10 Gb of data.