best practice for advertising peering fabric routes

Niels Bakker niels=nanog at
Wed Jan 15 20:46:25 UTC 2014

* clay at (Clay Fiske) [Wed 15 Jan 2014, 20:34 CET]:
>Semi-related tangent: Working in an IXP setting I have seen weird 
>corner cases cause issues in conjunction with the IXP subnet 
>existing in BGP. Say someone’s got proxy ARP enabled on their router 
>(sadly, more common than it should be, and not just from noobs at 
>startups). Now say your IXP is growing and you expand the subnet. No 
>matter how much you harp on the customers to make the change, they 
>don’t all do it at once. Someone announces the new, larger subnet in 
>BGP. Now when anyone ARPs for IPs in the new part of the range, 
>proxy ARP guy (still on the smaller subnet) says “hey I have a route 
>for that, send it here”. That was fun to troubleshoot. :)

Proper run IXPs pay engineers to hunt down people with Proxy ARP 
enabled on their peering interfaces.

	-- Niels.

"It's amazing what people will do to get their name on the internet, 
  which is odd, because all you really need is a Blogspot account."
			-- roy edroso,

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