[j-nsp] New 16port 10G Card and new MPC with 4x10G MIC Cards - coexistance of old DPCs and new Cards in same chassis -- looking for experience feedback

[Richard A Steenbergen]

On Fri, Aug 27, 2010 at 01:45:42PM +0200, Prochaska Gerhard wrote:
> 
> Our main goal is to use all ports of the card. Thats why we are at a 
> "proof of concept" LAB in amsterdam at the Juniper site from 2nd to 
> 3rd of September. We want to see if we can break the 120G Limitation 
> by using 2ports per pfe locally without switching over the backplane.

I've been unable to get a good explanation of the > 120G/slot potential 
of these cards, or even of the exact performance characteristics under 
different load conditions. At this point it's more a collection of 
stories than hard facts, but so far I've heard:

* Supposedly there is some capability to do local switching on the Trio 
PFE, but I've been told that support is extremely limited, and even 
doing something like configuring egress filters defeats the local 
switching and forces everything through the fabric.

* I've been told that under certain packet conditions, such as 1500 byte 
packets, you can't even get 30G line rate performance out of each PFE. I 
haven't been able to get ahold of any details about te math involved, 
but from what I've heard it's actually better to have smaller packets 
than bigger ones, the opposite of what you would normally expect to be 
the limitation. This sounds like it would be a fabric limitation not an 
LU lookup asic limitation, but who knows. :)

* The MX480 is supposedly in a much better fabric situation than the 
MX960, since it has the same fabric card as the 960 but needs to support 
fewer slots. Supposedly it can actually deliver something close to 40G 
of fabric capacity per Trio PFE, where the MX960 can only achieve 30G 
by running 3 SCBs in active/active/active with no fabric redundancy.

* Supposedly the reason the MX80 is able to get 60G of performance out 
of a single Trio PFE is that the normal 30G limitation comes from the MQ 
ASIC which interconnects Trio components having to split its capacity 
between MIC-facing and fabric-facing. Because MX80 has no fabric and a 
single pfe, the MQ can be reconfigured to handle 60G of MIC facing 
capacity. This would seem to imply that local switching on a MPC could 
support > 30G.

If anybody has better info, I'd absolutely love to hear it. Until then, 
I'm assuming that the "3D" in the MPC card names actually stands for how 
you'll be using them, "3 ports working, one Disabled". :)

-- 
Richard A Steenbergen <ras at e-gerbil.net>       http://www.e-gerbil.net/ras
GPG Key ID: 0xF8B12CBC (7535 7F59 8204 ED1F CC1C 53AF 4C41 5ECA F8B1 2CBC)