whatever happened to redundancy? in http://www.dslreports.com/forum/r21651201 en Tue, 09 Feb 2010 22:42:51 EDT Tue, 09 Feb 2010 22:42:51 EDT Re: whatever happened to redundancy? http://www.dslreports.com/forum/remark,21654522 NormanS : I did not lose connection to most of the sites people were not connecting with during that outage. But my ISP (at&t Yahoo! HSI) has their own peering agreements with Google, Microsoft, and Yahoo!, so all traffic to those sites leaves the local AT&T Internet Services (aka ATTIS) transit network directly for their respective transit networks; and never touches a Tier 1 network on the way:
There are currently eight recognized Tier 1 networks. If your ISP buys all transit to the Internet through just one of those Tier 1 networks, and that network goes down for any reason, you are hosed.

My ISP peers with at least two Tier 1 networks (AT&T Worldnet Services (ATTW; which is different from ATTIS), and Level 3), so I imagine that ATTW would pick up the load if Level 3 bombed.

There are also a number of other networks, at the Tier 2 level, which should, in a pinch, be able to route around a Tier 1 network gone south. More often than not, I never see a Tier 1 network in my routes; and about equally ATTW, or Level 3 when I do.

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Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum]]> http://www.dslreports.com/forum/remark,21654522 Tue, 30 Dec 2008 05:52:13 EDT Re: whatever happened to redundancy? http://www.dslreports.com/forum/remark,21652135 Kearnstd : id be more worried to why there was not backup diesels started up with in a minute or two of the data center dropping off grid.
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[65 Arcanist]Filan(High Elf) Zone: Broadband Reports]]> http://www.dslreports.com/forum/remark,21652135 Mon, 29 Dec 2008 17:48:08 EDT Re: whatever happened to redundancy? http://www.dslreports.com/forum/remark,21651823 bzmeteorite :
said by RadioDoc See Profile :

We'll wait for you to figure out how much of the Internet was actually "down" during this outage.

Extra credit: Level 3 is one transport provider. How many others are there?
Considering Level 3 is a Tier 1 provider, and it affected a wide area, I would imagine it affected many people, including other carriers (other Tier 1s that are peering, down to [especially single-homed] Tier 3s). That doesn't necessarily mean the effect was noticeable (in a crippling way) to all end-users, or wasn't countered by the other carriers.

Of course, the ones that are redundant would have just rerouted traffic (transit or peering) to another location, but that would have increased load on other circuits, possibly causing slow downs. Also assuming that the datacenter(s) in question weren't their only links in a chain to the rest of the world.

I skimmed the article and sub-articles, but was unable to find the cause of the Level 3 outage, only the AT&T one (also supported by Slashdot). I do find it interesting that a carrier as large as AT&T had power problems, usually backup power is N+1 or better. Are they really as reliable as they claim? Or only when the weather suits them?

Extra Credit: That depends on your definition of "transport provider". Assuming you mean a Tier 1, as Level 3 is, there are 7 others (AT&T, Verizon, Sprint, Qwest, Savvis, NTT, and Global Crossing). If you consider Tier 2s, there are likely thousands worldwide.
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What happens when you combine common sense and an outspoken personality?]]> http://www.dslreports.com/forum/remark,21651823 Mon, 29 Dec 2008 16:53:44 EDT Re: whatever happened to redundancy? http://www.dslreports.com/forum/remark,21651315 RadioDoc : We'll wait for you to figure out how much of the Internet was actually "down" during this outage.

Extra credit: Level 3 is one transport provider. How many others are there?]]> http://www.dslreports.com/forum/remark,21651315 Mon, 29 Dec 2008 15:02:16 EDT whatever happened to redundancy? http://www.dslreports.com/forum/remark,21651201 inteller : I thought the whole thought behind the Internet was to supposed to be redundant. ]]> http://www.dslreports.com/forum/remark,21651201 Mon, 29 Dec 2008 14:38:53 EDT