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Is multihoming hard? [was: DNS amplification]
In a message written on Sun, Mar 24, 2013 at 12:54:18PM -0400, John Curran wrote:
> I believe that the percentage which _expects_ unabridged connectivity
> today is quite high, but that does not necessarily mean actual _demand_
> (i.e. folks who go out and make the necessary arrangements despite the
> added cost and hassle...)
Actually, I think most of the people who care have made alternate
arrangements, but I have to back up first.
Like most of the US, I live in a area with a pair of providers,
BigCable and BigTelco. The reality of those two providers is that
from my house they both run down the same backyard. The both go
to pedistals next to each other at the edge of the neighborhood.
They both ride the same poles down towards the center of town. At
some point they finally diverge, to two different central offices.
About 80% of the time when one goes out the other does as well.
The backhoe digs up both wires. The pole taken out by a car accident
takes them both down. Heck, when the power goes out to a storm
neither has a generator for their pedistal. The other 20% of the
time one has an equipment failure and the other does not.
Even if I wanted to pay 2x the monthly cost to have both providers
active (and could multi-home, etc), it really doesn't create a
significanlty higher uptime, and thus is economically foolish.
However, there is an alternative that shares none of this infrastructure.
A cell card. Another option finally available due to higher speeds
and better pricing is a satellite service. These provide true
redundancy from all the physical infrastructure I described above.
It could be aruged then, the interesting multi-homing case is between
my Cable Modem and my Cell Card, however even that is not the case.
Turns out my cell hard has bad latency compared to the cable modem,
so I don't want to use it unless I have to, and it also turns out
the cell provider charges me for usage, at a modestly high rate,
so I don't want to use it unless I have to.
The result is an active/passive backup configuration. A device
like a cradlepoint can detect the cable modem being down and switch
over to the cell card. Sure, incoming connections are not persisitent,
but outbound it's hard to notice other than performance getting
TL;DR People paying for redundancy want physical redundancy including
the last mile. In the US, that exists approximately nowhere for
residential users. With no diverse paths to purchase, the discussion of
higher level protocol issues is academic.
Leo Bicknell - bicknell at ufp.org - CCIE 3440
PGP keys at http://www.ufp.org/~bicknell/
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