[c-nsp] Rant: ASR1000 MPLS (not) load-balancing

Saku Ytti saku at ytti.fi
Thu Jan 2 11:07:20 EST 2020

On Thu, 2 Jan 2020 at 17:42, Robert Raszuk <robert at raszuk.net> wrote:

> First most of the ASICs or NPs you get do just fine LEM or LPM at their line rate. And while processing wise they may be more cycles to do LPM your invoice amount for box is still the same :) I guess one vendor tried to do pure LEM box ... but you know the story there.

No box does line rate, there is no market for it and it's expensive.
Only way to do line rate is to stop using half or more of the ports.

> Then consider smart LPMs like Arista FlexRoute .. the advantages of LEM here are getting very marginal for the significant cost of control plane complexity.

Unsure how we evaluate complexity here and of what. But LPM/LEM
difference is shrinking in high end because there is strong market for
high performance LPM, doesn't change the fact that small table fast
LEM is fundamentally cheaper to implement.
Now when it comes to control-plane complexity, that doesn't care at
all on the bytes imposed, so what ever tunneling headers we come up
with, has no inherent bearing to complexity of control-plane. There is
no reason for IP to simpler or more complex in control-plane compared
to MPLS.


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