[c-nsp] /18 and multihomed BGP

[Adam Armstrong]

On 13/08/2010 17:00, Heath Jones wrote:
> Robert's response pretty much covers it all really.
> If those 2 ISP's are advertising /24's out to the wider internet, your
> screwed. Traffic will never come down via this new ISP.
> The way to solve it, is to advertise the /24's as you already are, but
> get those 2 ISP's to summarize into a /18 before they export, or you

That's quite a confusing explanation. You don't get the ISP to 
"summrize" anything. You announce both the /18 and the /24s. The /24s 
should be advertised either with no-export or with other communities to 
suppress their advertisement outside of the ISPs (or region) involved.

adam.