RE: Anyone familiar with the SBC product lingo?

[Hannigan_Martin]

From: owner-nanog@merit.edu [mailto:owner-nanog@merit.edu]On Behalf Of
Michael.Dillon@radianz.com
Sent: Friday, April 15, 2005 6:34 AM
To: nanog@merit.edu
Subject: Re: Anyone familiar with the SBC product lingo?

> you'll never get better redundancy than having more than
one carrier.

On the contrary, you get better redundancy by sticking to
one carrier and making sure that they really provide
separacy though the entire span of the circuit. If you
have two carriers running fibre to yoiur building down
the same conduit, then you do NOT have separacy and as
a result, the redundancy is not there.

Which is the case in about 99% of the commercial buildings
providers serve. Unless you're designed as a carrier hotel
or a colo (even some colos aren't diverse entrance facility),
this is the de-facto standard. The reason why is carriers
et. al. must pay for conduit access to a building and it
impacts pricing, especially if you're not servicing a huge
load of service to the building. From the entrace facilities,
carriers typically also pay riser conduit fees.

Service delivery inside of the prem is insidiously complicated
unless you understand a little RE and how OSP is linked to
the ISP (in side plant).

Of course, you can get separacy with two carriers but
it is generally more work to verify that the two companies
do not share fibre or conduit or tunnels.

Im a metro loop, they are almost certainly going to share
the same path. It is less certain that they will share a
conduit. This is standard if you have the route diversity,
which is why you want the provider diversity to make it
all work.

Hope that helps.

-M<

[michael.dillon2]

> On the contrary, you get better redundancy by sticking to
> one carrier and making sure that they really provide
> separacy though the entire span of the circuit. If you
> have two carriers running fibre to yoiur building down
> the same conduit, then you do NOT have separacy and as
> a result, the redundancy is not there.

Which is the case in about 99% of the commercial buildings
providers serve.

Do you have any sources of data to back up that number?
I believe that you are wrong and that it is not 99%.
In Manhattan and similar city centers, I believe that
your view is mostly correct but even there I don't
believe that it is as high as 99%. And in places like
Silicon Valley or Sacramento, the majority of
commercial buildings are surrounded by parking lots,
patches of grass and trees. In those areas, if your
building doesn't have dual entrance, it is feasible
to make it so. Maybe not easy, but definitely within
the realm of feasibility.

Service delivery inside of the prem is insidiously complicated
unless you understand a little RE and how OSP is linked to
the ISP (in side plant).

No argument there. People who want to buy separacy have got
to learn all of these things in order to guarantee that
they are getting what they think they are getting. Once
the market has matured a bit, I expect that 3rd party
network suppliers will take over that duty. These 3rd party
separacy providers won't have their own networks for the
most part, but will do the donkey work to make sure that
their carriers are supplying true separacy. In cities
like New York and Philly, I would expect this type of
third party to put in some of their own metro network
links to work around hot-spots where it is too hard to
guarantee that the carrier is really providing separacy.

This is not unlike the way in which the tier 2 ISPs of
the 90's were able to provide better uptime than the
tier 1's because they aggregated access to several
tier 1 networks.

Im a metro loop, they are almost certainly going to share
the same path. It is less certain that they will share a
conduit. This is standard if you have the route diversity,
which is why you want the provider diversity to make it
all work.

I'm not sure what you mean by "path" here, but people who
want to buy separacy want those circuits to be physically
separate at all points and they want the distance between
circuits to be sufficiently great that they two circuits
do not share fate. Two sides of the Baltimore tunnel
would not qualify as truly separate paths by those standards.

This is why I use the term "separacy" rather than "diversity".
Separacy seems to have originated among people planning
SANs (Storage Area Networks) to interconnect mission-critical
data centers in the same metropolitan area.

--Michael Dillon