nested prefixes in Internet

Roy r.engehausen at
Mon Oct 10 17:18:33 UTC 2016

I don't think I ever said that ISP-B would announce the /19.  That would 
only be announced by ISP-A.  ISP-B would only announce the /24 that has 
been delegated to it.

If the ISP-A/ISP-B link goes down then the /24 would be seen only via 
ISP-C which is the desired result.

On 10/10/2016 9:16 AM, joel jaeggli wrote:
> On 10/10/16 9:04 AM, Roy wrote:
>> The solution proposed allows ISP-B to use both paths at the same time,
>> needs ISP-C to minimal changes, and has low impact on the global
>> routing tables..  I have successfully used it in the past and my old
>> company is still using it today.
> Having two parties in control of a prefix announcement is a bit of a
> disaster. ISP A becomes partitioned from isp B isp B does not withdraw
> the covering aggregate and black-holes the of ISP A that lands on it's
> edge. bummer.

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