Re: Statistical Games Providers Play (RE: availability and resiliency)

[Vijay Gill]

On 30 Sep 2000, Sean Donelan wrote:

> If you look at network backbones, almost everyone uses the same
> vendors, supplying essentially the same equipment, and nearly the same
> network design.  So why would different providers have different
> availability numbers?  Is it just an accident of the statistical
> series, some providers had their failures earlier but everyone will
> end up the same in Year Infinity? Or are there real differences,
> besides price, between providers?

There appear to be two major and some minor variants in backbone
engineering and architecture. The major ones being the UUNET design and
the Sprint/Qwest design for circuit layout and aggregation/hierarchy.  
There are a lot more variants regarding the routing architecture (IGP
setup, bgp setup, et al), and depending on various failure modes, some are
better than others for a subset of failures and vice versa.

The hierarchical UUNET design for example, is fairly dense in terms of
volume, with a small time diameter per region for a network of that size,
which allows for some local optimizations. And if you get two circuits
into two regions, some failures in one region can be isolated and
compartmentalized, without a major spillover into the neighboring regions,
which would not be the case in a large flat network.

As always, with good engineering, comparable reliability can be
established, given appropriate amounts of money being thrown at the
problem.

/vijay