[j-nsp] 400G is coming?

Tim Rayner Tim.Rayner at aarnet.edu.au
Mon Mar 18 17:05:00 EDT 2019

> It seems these are oversubscribed to the backplane.  8×100G + 2×400G
> is 1.6 Tbit/s, and 12×100G + 3×400G is 2.4 Tbit/s, but all three of
> MX240, MX480 and MX960 are listed as having 1.5 Tbit/s max per slot.
> (And is that 1.5 Tbit/s in *and* out, or is that just 750 Gbit/s per
> direction?)
As I understand it, when a 400G port is enabled, 3 of the 100G ports are made un-available (not sure whether there is an option for sub-rate on the 400G port keeping more of the 100G ports available), hence there will be a limit of 1.5 Tbps per slot with no over-subscription.  It is actually a 15x100G card... each group of 5 ports can enable one of its ports as 400G, thereby disabling three of its other 100G ports... there is 500Gbps of capacity per port group = available as 5 x 100G, or 1 x 400G + 1 x 100G.

The card with less capacity (ie. 2 groups of 5 ports, rather than 3 groups of 5 ports) just reduces the electronics and thereby the power consumption by 1/3.

I hope this helps


Tim Rayner
Optical Engineer, AARNet Pty Ltd
street address: Building 9, Banks Street, YARRALUMLA  ACT  2600
postal address:  GPO Box 1559, CANBERRA   ACT   2601
t. +61 2 6222 3575     f. +61 2 6222 3535     e. Tim.Rayner at aarnet.edu.au
w. www.aarnet.edu.au

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