Anyone familiar with the SBC product lingo?

Thu Apr 14 22:09:47 UTC 2005

>
>(Anybody here *NOT* seen cases where the 2 fibers leave the building 
>on opposite
>sides, go down different streets - and rejoin 2 miles down the way because
>there's only one convenient bridge/tunnel/etc over the river, or similar?)

Even if that's not the case, and it's still perfectly separated all 
the way to the CO, the CO is a common point of failure.  Granted, the 
failure modes are very unlikely to occur for a CO, but they do exist. 
Those two separate paths of the ring have a way of always coming 
together somewhere, by design.

The only way to insure that doesn't happen is to have two sources of 
connectivity to a building, from two separate local carriers that 
have fiber going in two opposite directions (eg., one carrier to the 
east, one to the west), to two opposite area codes/LATAs that get 
transit from two different transit providers that have POPs in cities 
that are geographically the furthest apart (one to the north, one to 
the south, or east west, or whatever).  As long as everything keeps 
heading in complete opposite directions, it becomes very assured that 
the common modes of failure diminish with distance.

This tactic works, and works well with IP using BGP, but it's 
something that would be beyond my scope of expertise to attempt to 
implement with anything else.

(someone mentioned earlier charging the 2 9's rate for providing 5 
9's service...... it was a wake up call to myself.....I'm that guy!)

On a somewhat related, but kind of a little off topic note:

It always makes me chuckle inside to hear data centers tout their 
"dual grid connections" as a way to insure that the power "is hardly 
ever interrupted"  Same basic principal.  Sure they might be separate 
distribution feeders, and they might even come from separate 
distribution substations, and the subtransmission that feeds the 
distribution substations might even come from separate transmission 
substations... but within about a minimum of a 60-100 mile radius, 
it's nearly always connected together by the transmission grid.

Now, if there was a data center that had a power feed connection to 
say, ERCOT, the Eastern Interconnection, and the Western 
Interconnection.... THAT would be something to brag about.