[c-nsp] PE "Sprawl" - P/Core Router suggestions.

[adamv0025 at netconsultings.com]

> Phil Bedard
> Sent: Thursday, December 29, 2016 7:30 PM
> 
> Afaik, all the Cisco Jericho/Qumram based cards/fixed boxes use the 16MB
> on-chip and 4GB of external DRAM.  The 4GB is broken up into 1000 byte
> chunks from what I remember.
> 
Hmm 1000 byte chunks? That's not very efficient is it. 

Yes the Cisco incarnation of the DNX/Dune family is using 16M on-chip
in-flight buffer and 4G off-chip packet delay buffers. 
But I can't dig out how does the pre-classifier, arbiter and backpressure
work on these chips.
I was pleasantly surprised by the pps rate though, round ~80% line-rate for
64B at L2 is not that bad (it's like ASR9k's Tomahawk NPU). 
But I would love to know what performance tax will QOS and sFlow incur on
the Dune chips.   


adam


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