Curiosity about AS3356 L3/CenturyLink network resiliency (in general)

Sun May 20 07:16:25 UTC 2018

Den 20/05/2018 kl. 05.43 skrev valdis.kletnieks at vt.edu:
> On Sat, 19 May 2018 22:28:07 +0200, Baldur Norddahl said:
>> What happened to do not trust anyone? Create your own resiliency by being
>> multihomed to as many transits you can afford.
> Re-read what David Hubbard said:
>
>> unacceptable period of time (many hours).  Iâ€™m learning that the entire
>> market is served by just two fiber routes, through cities hundreds of miles
>> away in either direction.  So, basically two fiber cuts, potentially 1000+
>> miles apart, takes the entire region down.
> If in fact there's only two fiber conduit approaches to the area,  he's
> basically stuck no matter how many companies sell him bandwidth in those two
> conduits. He can contract with 8 companies to have 4 paths through each
> conduit, and 2 cable cuts *still* leave him dead in the water.

He is complaining about AS3356 in specific and claiming they COULD 
reroute around it but choose not to. This leads me to assume there are 
alternatives. Two places, Miami and Texas, are mentioned and that a 
double fault, one in Miami and another in Texas would bring down the 
network. I am from Europe, but am I to believe that Miami and Texas (or 
anywhere between those two) are served by only two fiber conduits? This 
would have several big states only connected two ways.

The question was if downtime on a transit provider of many hours is 
unacceptable. I am offering my experience that this happens to all of 
them. Some of them can have problems that last days not hours. Do not 
ever assume that a so called "tier 1" network is good as your only transit.

Also a total cut of from the world is the good kind of trouble they can 
have. That would just lead them to lose a large part of the global 
routing table. Your router will automatically choose one of your other 
transits. The bad kind of trouble is when they have packet loss to some 
few (but important) destinations and your customer thinks it is you that 
is having issues. And basically all you can do about it is to "shutdown" 
the session and wait until they fixed the issue.

I am offering the view that one might consider that kind of downtime 
unacceptable, but it is just a matter of fact that they all have it. The 
two options to avoid it is to buy from a smaller local ISP instead - one 
that has multiple transits. Or to have multiple transits yourself and be 
prepared to deal with it.

Regards

Baldur