[j-nsp] Junos 20 - slow RPD

[Saku Ytti]

Hey,

> On MX204 with ~4M routes, after upgrading from 18.2 to 20.2 the RPD is
> way slower in processing BGP policies and sending the routes to neighbors.
> For example, on a BGP group with one neighbor and an export policy
> containing 5 terms each matching a community it takes ~1min ( 100% RPD
> utilisation ) to send 1k routes to the neighbor in 20.2 compared to 15s
> in 18.2.
> Disabling terms will reduce the time.
>
> Anyone experienced something similar?

I don't recognise this problem specifically. It seems rather terrible
regression so you probably should either open a JTAC case or do the
Junos dance. If you have a large RIB/FIB ratio allowing more than 1
core to work on BGP will produce improvement:

set system processes routing bgp rib-sharding number-of-shards 4
set system processes routing bgp update-threading

This is a disruptive change. JNPR wanted us on 20.3 (we are on
20.3R3-S2) for rib-sharding, but we did run it previously on 20.2R3-S3
with success. We are currently targeting 21.4R1-S1.

If you have memory pressure, you can expand the default 16GB DRAM to
24GB DRAM via configuration toggle (post 21.2R1). If you are
comfortable hacking QEMU/KVM config manually, you can do it on any
release and can entertain other sizes.

-- 
  ++ytti