[j-nsp] Hardware configuration for cRPD as RR

[Michael Hare]

I recognize Saku's recommendation of rib sharding is a practical one at 20M routes, I'm curious if anyone is willing to admit to using it in production and on what version of JunOS.  I admit to have not played with this in the lab yet, we are much smaller [3.5M RIB] worst case at this point.

-Michael

> -----Original Message-----
> From: juniper-nsp <juniper-nsp-bounces at puck.nether.net> On Behalf Of
> Saku Ytti via juniper-nsp
> Sent: Thursday, December 7, 2023 12:24 AM
> To: Thomas Scott <mr.thomas.scott at gmail.com>
> Cc: Vincent Bernat <bernat at luffy.cx>; juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] Hardware configuration for cRPD as RR
> 
> From a RPD, not cRPD perspective.
> 
> - 64GB is certainly fine, you might be able to do with 32GB
> - Unless RRs are physically next to clients, you want to bump default
> 16kB TCP window to maximum 64kB window, and probably ask account team
> for window scaling support (unsure if this is true for cRPD, or if
> cRPD lets underlying kernel do this right, but you need to do same in
> client end anyhow)
> - You absolutely need sharding to put work on more than 1 core.
> 
> Sharding goes up-to 31, but very likely 31 is too much, and the
> overhead of sharding will make it slower than running lower counts
> like 4-8. Your core count likely shouldn't be higher than shards+1.
> 
> The sharding count and DRAM count are not specifically answerable, as
> it depends on what the contents of the RIB is. Do a binary search for
> both and measure convergence time, to find a good-enough number, I
> think 64/32GB and 4-8 cores are likely good picks.
> 
> On Wed, 6 Dec 2023 at 22:30, Thomas Scott via juniper-nsp
> <juniper-nsp at puck.nether.net> wrote:
> >
> > Also very curious in this regard.
> >
> > Best Regards,
> > -Thomas Scott
> >
> >
> > On Wed, Dec 6, 2023 at 12:58 PM Vincent Bernat via juniper-nsp <
> > juniper-nsp at puck.nether.net> wrote:
> >
> > > Hey!
> > >
> > > cRPD documentation is quite terse about resource requirements:
> > >
> > > https://www.juniper.net/documentation/us/en/software/crpd/crpd-
> deployment/topics/concept/crpd-hardware-requirements.html
> > >
> > > When used as a route reflector with about 20 million routes, what kind
> > > of hardware should we use? Documentation says about 64 GB of memory,
> but
> > > for everything else? Notably, should we have many cores but lower boost
> > > frequency, or not too many cores but higher boost frequency?
> > >
> > > There is a Day One book about cRPD, but they show a very outdated
> > > processor (Sandy Lake, 10 years old).
> > >
> > > Is anyone using cRPD as RR with a similar scale and can share the
> > > hardware configuration they use? Did you also optimize the underlying OS
> > > in some way or just use a stock configuration?
> > >
> > > Thanks.
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> 
> 
> --
>   ++ytti
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