Hi, On Mon, Feb 21, 2011 at 04:09:55PM -0500, Chris Wallace wrote: > In order to fix the issue I had to manually shutdown the peer till > Provider A confirmed the change they made had been reverted. This > isn't the first time we have seen this issue with our various > providers, how can I prevent issues like this from happening in > the future?
Give your money to a provider that knows their trade.
Seriously: if they break their network in a way that BGP keeps working
but packets fall into a black hole, there is no 100% reliable way to
make your routers auto-failover to the other provider.
What you could try to do is: either run nagios (or your ping tool of
choice) to a number of selected targets that live behind provider A and
provider B, and manually shutdown either one if something breaks in
big ways, or try to couple "ip sla" + event manager in the cisco box
to do this in an automated way.
The problem with this approach: image you ping, say, "www.yahoo.com"
and one day yahoo says "we're sick of all these ping packets, we're
going to filter them!", all of a sudden, your routing falls over to
provider B because the ping probe says "yahoo is down, must bei
provider A failing again!" - so you need to ping a number of targets
and then decide whether "enough" are down... which has its own
pitfalls, in case provider A actually manages to only blackhole yahoo,
but neither google nor bing...
gert
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Gert Doering - Munich, Germany [email protected]
fax: +49-89-35655025 [email protected]
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