RE: Devil's Advocate - Segment Routing, Why?

[<adamv0025 () netconsultings com>]

Hi Baldur,

 

> From memory mx204 FIB is 10M (v4/v6) and RIB 30M for each v4 and v6.

And remember the FIB is hierarchical -so it’s the next-hops per prefix you are referring to with BGP FRR. And also 
going from memory of past scaling testing, if pfx1+NH1 == x, then  Pfx1+NH1+NH2 !== 2x, where x is used FIB space. 

  

adam

 

From: NANOG <nanog-bounces+adamv0025=netconsultings.com () nanog org> On Behalf Of Baldur Norddahl
Sent: Saturday, June 20, 2020 9:00 PM



I can't speak for the year 2000 as I was not doing networking at this level at that time. But when I check the specs 
for the base mx204 it says something like 32 VRFs, 2 million routes in FIB and 6 million routes in RIB. Clearly those 
numbers are the total of routes across all VRFs otherwise you arrive at silly numbers (64 million FIB if you multiply, 
128k FIB if you divide by 32). My conclusion is that scale wise you are ok as long you do not try to have more than one 
VRF with a complete copy of the DFZ.

 

More worrying is that 2 million routes will soon not be enough to install all routes with a backup route, invalidating 
BGP FRR.