[j-nsp] Summarize Global Table

[Robert Raszuk]

Hi Pavel,

> Robert, is there any non-production implementation of simple-va, which we
> could play with?

The only implementation I am aware of is cisco ios component code. Yes 
there are non-production EFT images you could perhaps get from cisco to 
play around with it.

Since I have switched recently and I am not longer a vendor, but an 
operator you will need to ask your cisco colleagues to get you some test 
images.

> The main concern here is, of course, whether a router will
> be infinitely installing/withdrawing tons of FIB entries because of
> 'natural' prefix flaps, how much black-hole/loop this will create in
> practice, and how to deal with it. Did anyone perform some research of this?
> Any reports exist?

The router with simple-va functionality enabled will not install nor 
withdraw even single additional route on top of what it would do when 
simple-va feature is not enabled. So it is guaranteed to be no less then 
today.

We simply added logic to table-map filter code which with matches on 
next hop of less specific route suppresses covered more specifics with 
identical next hop. The only real additional price (there is no free 
lunch) is extra CPU when you need to walk back the table in the event of 
some prefix just with mask between less specific and more specific get's 
into the RIB/FIB with different next hop. But if I would deploy this 
functionality it would be to save the edge router's FIB and do it within 
the POP while POP boxes would still keep full table. That one that extra 
walks and extra CPU does not need to be used.

Btw as a side note I spoke to some Juniper colleagues and there really 
liked the idea too :) Btw ... it equally well works for Internet as it 
works for VPN vrfs.

Best,
R.