Rate-limiting BCOP?

Saku Ytti saku at ytti.fi
Sun May 31 15:05:48 UTC 2020

On Sun, 31 May 2020 at 17:37, <adamv0025 at netconsultings.com> wrote:

> Shouldn’t the egress FIA(NPU) be issuing fabric grants (via central Arbiters) to ingress FIA(NPU) for any of the VOQs all the way up till egress NPU's processing capacity, i.e. till the egress NPU can still cope with the overall pps rate (i.e. pps rate from fabric & pps rate from "edge" interfaces), subject to ingress NPU fairness of course?

This is how it works in say MX. But in ASR9k VoQ are artificially
policed, no questions asked. And as policers are port level, if you
subdivide them via satellite or vlan you'll have collateral damage.
Technically the policer is programmable, and there is CLI, but CLI
config is binary between two low values, not arbitrary.

> Or in other words, shouldn't all or most of the 26Gbps end up on egress NPU, since it most likely has all the necessary pps processing capacity to deal with the packets at the rate they are arriving, and decide for each based on local classification and queuing policy whether to enqueue the packet or drop it?

No, as per explanation given. Basically don't subdivide ports or don't
get attacked.


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