[j-nsp] MX960 with 3 RE's?

Christopher E. Brown chris.brown at acsalaska.net
Fri Jan 15 07:59:41 EST 2016


The MPC2-Q is an advanced per unit queueing card and has QX, it also
runs against the lower/original fabric rate.

The 16XGE rate is a port mode card with no QX, and it supports the first
of the fabric speed increases.

The published capacity of the MPC2-Q is 30G per MIC with a supplied by
Juniper actual worst-case figure of 31.7G, climbing to about 39G with
larger frames.

This matches with my own test results and it does not change with SCB model.


On 1/15/16 03:47, Adam Vitkovsky wrote:
>> From: Saku Ytti [mailto:saku at ytti.fi]
>> Sent: Friday, January 15, 2016 10:18 AM
>> On 15 January 2016 at 03:13, Christopher E. Brown
>> <chris.brown at acsalaska.net> wrote:
>>> When the same folks were asked about the 16XGE card and the 120G (and
>>> later 160G) performance it was indicated that there was an additional
>>> layer of logic/asics used to tie all 4 trios in the 16XGE to the bus
>>> and that these ASICs offloaded some of the bus related overhead
>>> handling from the TRIOs, freeing up enough capacity to allow each TRIO in
>> the 16XGE to provide a full 40G duplex after jcell/etc overhead.
>>
>>
>> Sorry Christopher for being suspicious, but I think you must have done some
>> mistake in your testing.
>>
>> Only difference that I can think of, on top of the multicast replication, is that
>> 16XGE does not have TCAM. But that does not matter, as the TCAM isn't
>> used for anything in MPC1/MPC2, it's just sitting there.
>> MPC1/MPC2 can be bought without QX. You specifically metnion '3D-Q'.
>> If you were testing with QX enabled, then it's wholly different thing.
>> QX was never dimensioned to push all traffic in every port via QX, it's very
>> very much underdimensioned for this. If MQ can do maybe ~70Gbps
>> memory BW, QX can't do anywhere near 40Gbps. So if you enable QX or
>> ingress+egress, you're gonna have very very limited performance.
>>
> Saku is right, if you do the math then 40.960Gbps is a theoretical maximum for QX as a whole.
> 
> adam
> 
> 
> 
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