On 06/18/2009 06:01:36 PM, tico wrote:
The number of networks that filter prefixes smaller than /22 don't
appear to be that numerous IMHO, but if they do, your /24 will
still be reachable as they'll see the larger /19 or whatever from
your provider that it's carved out of.
But not from the 2nd provider, which defeats the purpose:
having a reliable Internet connection no matter what.
I disagree.
"Having a reliable Internet connection no matter what" fails (in my
experience) much more frequently for other reasons than not being
able to reach the small portions of the world that filter "le 22" ...
like power failure, split-brain load balancers, human error, etc.
I'm sure you're right.
On one of my routers (pulling down a full table), I see
<snip>
That should be enough of an answer, I think. YMMV.
Pretty good looking answer. Thanks.
Any other sort of
outage, it does not matter if the problem's in a router
half way around the world, and it's my head on the block.
That's the world of I.T.
You can spend tons of money [and time] chasing after potential
problems that could occur on the other side of the world, and trying
to add more theoretical "9's" to your availability, but in my
experience keeping clueful people around and solving the most common
failure modes first and adding decent monitoring/logging tools pays
off much better.
Even the "problem on the other side of the world" issues tend to be
relatively easy to work around:
a) Tier 1 de-peering. solution, don't buy transit from a single
tier-1 operator, or from a tier-1 operator at all.
b) weird BGP bugs, like the confederation-in-AS4 bug that spread from
some small ISP in the Ukraine and affected a bunch of machines around
the world. solution, have a fall-back default route on at least one
of your BGP speakers and/or have at least one BGP speaker be a router
that uses a completely-different BGP stack and hope that one bug
won't affect every implementation.
Regardless, you'll probably be bitten much more often by common
problems before you see these sorts of issues being the limiting
factors in your environments overall availability. Especially since
it doesn't sound like you're a datacenter.
No, we're not a datacenter.
Thanks for the good advice.
Ultimately, what it comes down to is politics. What reasons will
management accept should there be a failure of connectivity.
Karl <[email protected]>
Free Software: "You don't pay back, you pay forward."
-- Robert A. Heinlein
