[j-nsp] Summarize Global Table

[Chris Morrow]

On 10/26/2011 04:30 AM, Pavel Lunin wrote:

> With simple-va a single prefix flap can mean quite a lot of new entries.
> The problem, which can arise here, is not the number of FIB entries, but
> the speed of populating (BTW, EX8200 is not the best here either). I'm
> not saying this is a problem definitely, but just wondering if someone
> has researched, whether (and when) this can become a problem in real life.

with any solution comes a tradeoff. the two large problems in this
discussion are speed (of change) and size (of total footprint).

All routing platforms have a bottleneck at rib -> fib download.
All routing platforms have limits to how much rib memory can occupy.
All routing platforms have limits on the fib size (in hardware and
software).

The removal of a large aggregate (say 4/8) and the subsequent required
addition of all of the subnets under 4/8 could certainly be
'interesting' to observe.

Interesting as well is that 4/8's origin doesn't have to be the flapper,
just your network (or an intermediate) changing attributes (or exit
path!) could be enough to induce this problem, no?

-chris