The Myth of Five 9's Reliability (fwd)

Deepak Jain deepak at ai.net
Thu Apr 25 20:25:42 UTC 2002



[stuff missing]
When applied randomly to the Internet, I suppose that means if you can dial
into a RAS and establish a PPP/IPCP session, but the RAS' connection to the
Internet is down, then the service is up :-)

[stuff missing]

I seem to remember a large internet provider's service contract reading
something to the effect of. "Your server is considered down if customer
router cannot pass packets [or ping] with service provider's immediate
upstream router." This is a functional description of the above for
dedicated lines as customer aggregation routers never talked to the
internet, so if there was a problem at a transit router you weren't getting
anywhere.

A modern contract I saw recently defined "up" for colocation purposes as
"the customer's assigned gigabit port is available." Though available was
not a defined term, one could not easily apply that to a ports' willingness
to pass packets. One could say a congested port was not available though I
guess.

Deepak Jain
AiNET




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