[c-nsp] BGP table growth and memory

[Joe Maimon]

David J. Hughes wrote:
>>But what if the /19 goes away but the /24s remain?  If you've discarded
>>them, you have no way to know that you can reinstall them, and now
>>you've lost connectivity to that site when the rest of us still see it.
> 
> 
> That's an implementation issue and I'm sure the smart folk at Cisco 
> could come up with some mechanism for dealing with it (eg keep the 
> discarded routes compressed outside the RIB and FIB for reinsertion if 
> needed for example).  This had been part of the original discussion and 
> Rodney was chatting with some engineering type guys about options.
> 
> 
> David
> ...
> 

I think the answer to this lies in where you look at it.

Instead of not installing the aggregate's member routes and potentialy 
missing them when the aggregate gets withdrawn, the way to implement 
this is as a feature to suppress ADVERTISING the member prefixes, even 
while keeping them in the table.

All algorithms on throwing out routes based on the existance of other 
routes should be adjusted to algorithms restricting further 
*advertisiment*, but the routes should be kept.

So if you want your NPE's life extended you ask your Peers to turn that 
knob.

Furthermore this would work well with a border+core RR setup, where the 
knob is turned on at the border.

Ideally this would be done as close to the source as possible, i.e. his 
peers.