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Re: Of Fiber Cuts and RBOC Mega-mergers

  • From: Michael.Dillon
  • Date: Tue Aug 09 05:50:00 2005

> The unfortunate part of all this is there is a demand for diversity,
> especially from the financial and government sectors.  One of the 
> big problems is that clients seldom know which providers or 
> combinaiton of providers give them the most diversity.  There are 
> some intersting ways to claculate the optimal set of providers by 
> price and diversity, but getting the data is quite difficult.
First of all, I think the terminology is part of the problem.
Historically, people bought redundancy or diversity by choosing
two different providers or perhaps by asking one provider to 
provide two different routes, i.e. dual entrance. But this
was not enforced contractually and it certainly was not built
into the business and operational processes of the carriers.
Redundancy and diversity where just a fantasy shared between
customers and their sales reps.

There are some large enterprises who build their internal operations
around data centres and Storage Area Networks, essentially
disk farms that are connected to multiple locations with
application servers. These people chose to use the word "separacy"
to refer to a network connections that do not share fate
anywhere along the path. That means that they do not share
the same fibre, or cable, or conduit, or street/tunnel/bridge.
In my company we use this term for the way in which we deliver
various market data feeds over IP networks to our customers.
In addition to the physical separacy our network does not 
have a single best route at the IP layer. There are two paths
through different circuits and different routers and all packets
take both paths simultaneously. 

Now obviously, either the SAN style of separacy or the market
data feed style costs a bit more money. But the benefit to the
customer is that the concept of seperacy is built into the business
and operational processes, i.e. it is not just a polite fiction
of sales people. Of course, we like all other ISPs, continually
struggle with carriers who don't have this concept themselves
and must continually check, monitor and double-check the carrier's
grooming practices.

I think that in order to resolve this issue on the large scale
we need to have a shared vocabulary and a shared vision of building
a resilient network that is not brittle. The rhetoric of an
Internet with one level of service that is "good enough" has
fogged people's thinking. And the rhetoric of a network with
magic software knobs to provide multiple levels of service
has also fogged people's thinking. 

Until we reach general agreement that the way to make a network
resistent to failure is to provide multiple redundant paths 
at all layers from physical to IP, this situation will not

--Michael Dillon

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