Re: OT: WAN Bandwidth Aggregation

How much bandwidth you need depends on the desired QOS.

Here is a nice link that describes one way to figure out how much bandwidth
you need. The first few paragraphs are a nice read and a must IMO for any
sizing exercise.
http://www.cisco.com/en/US/docs/ios/12_3t/12_3t14/feature/guide/gtcbandw.html

The way I do it, is try to find out the recommended BW for the apps that
are running. Try and add up the heavy apps to help you understand the
recommended network utilization. Next I try and figure out what "user
experience" is needed for these apps ... something that is not quick or
easy.

Some apps are more tolerant and or the user experience is not affected by
delays, jitter, or minimal lost packets.

For the apps which cannot handle delays, jitter, or lost packets, then you
will likely need to determine if these are predictable (such as voice) and
also configure QoS for them for. Predictable traffic like voice is easy to
size for, and you are an expert in QoS Joe!

Try and keep your QoS configs to a minimal and make sure that similar
traffic is found within each queue (I know you already know this ...).Do
not create too many queues as this would increase the needed bandwidth ...

For sizing purposes, keeping these apps in the same queue means that you
can take advantage of statistical mux.

What should your over subscription rate be? I work with a lot of SPs that
engineer for 4:1 with QoS on the uplinks. The amount of real-time traffic
will need to be understood so that you can size the link ...

Is this right for you? ;-) ... as mentioned the amount of BW you need
depends on the desired QoS.

Rock on Joe!
Andrew

*PS - with the holiday season coming ... a must watch!!!!!!!!*
http://www.wimp.com/cashregister/

On Thu, Nov 3, 2011 at 10:33 AM, Joe Astorino <joeastorino1982_at_gmail.com>wrote:

> I was wondering if I could pick your brains for a second guys. When you
> are designing or upgrading a WAN what do you feel is a good guideline for
> deciding how much actual bandwidth you need, particularly at an aggregation
> point. In the SRND for campus LANs it gives nice aggregation ratio numbers
> for access --> distribution and distribution --> core but I can't find any
> similar numbers for WANs as of yet.
>
> You all know the drill, trying to justify $$$ for more WAN bandwidth and
> would like to have some best practice recommendations that are black and
> white to show people. One main thing is internet aggregation. At the
> moment I have a bunch of remote sites that get their internet access and
> WAN services over an MPLS solution. The SP provides internet access in the
> MPLS cloud via a "network based firewall" solution. I am trying to
> determine the proper amount of bandwidth I should ideally have at that
> aggregation point and others in the network
>
> Anybody have a resource or input on this topic?
>
>
>
> --
> Regards,
>
> Joe Astorino
> CCIE #24347
> Blog: http://astorinonetworks.com
>
> "He not busy being born is busy dying" - Dylan
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-- 
Andrew Lee Lissitz
all.from.nj_at_gmail.com
Blogs and organic groups at http://www.ccie.net