At 01:05 PM 10/19/2005, John Dupuy wrote:
For the customer with an Internet "mission critical app", being tied
to a Tier 2 has it's own set of problems, which might actually be
worse than being tied to a Tier 1.
The key word is "might". In fact, I would posit that a Tier 2 with
multiply redundant transit to all of the Tier 1s could theoretically
have better connectivity than an actual Tier 1. The Tier 2 transit
provides flexibility that the transit-free Tier 1s do not have. Just
my opinion.
Anyway, it has been my experience that most (but not all) of the
customers that want to "multihome" are _really_ wanting either: A.
geographic/router redundancy. or B. easy renumbering. Geographic
redundancy can be done within a single AS and IP block. They just
don't know to ask it that way. (And easy renumbering will eventually
be solved with v6. Eventually.)
It has been my experience that most needing to multihome wish to do
so to avoid failures within an ISP, failures with a circuit to the
ISP, and failures with routers.
I should think that with the recent L3/Cogent issue, it should be
QUITE clear that multihoming requires linking to two separate
backbones, or two separate regionals that buy transit from multiple
backbones. Vagaries in backbone providers is high on the list, IMO,
and rules out the "multihome to a single provider" approach.
The demand for multi-homing might not be as great as suspected.
John
