Thanks for the response.
You want to optimize for the lowest monetary cost network that still allows you to meet all the SLA's you've negotiated. And this depends on what you negotiated - for instance, if the SLA specifies 3 9's of reliability, spending money to build a 4 9's network is cutting into your profits. Of course, if the SLA's are biased towards latency or bandwidth, you'll have to consider those.
There is always someone claims his network could reach availability 99.9% or so, but I don't understand how a network availability should be measured or figured out. Is there any paper on this? Focusing on SLA of a network, ISP network or PoP site should not carry only one type of business traffic ( e.g. broadband access, MPLS-VPN, L2 VPN etc.), if we consider it simply by taking network as a single system optimization will surely be of no usage. Looking at PoP site , is there any recommendation on its design? a layer-2 access model is better than router based system? Joe
And remember that there usually isn't one right answer for anything but the most simple problems - almost always, some constraint will be placed on the solution. Often it's of the form "The salesdroid just promised XYZ", also known as the "Don't let your mouth write no check your router can't cash" syndrome. If it isn't that, it's a financial issue inside the company - there's always the network you *want* to build, which is almost never the network that your revenue stream will allow you to build....
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