[c-nsp] WS-X6748-SFP support

[Nick Hilliard]

Chris Knipe wrote:
> Will a X6748-SFP work on the normal 6506 (not -E) with a SUP720 or
> similar?

yes.  On a not-6513, it can be put into any slot and it can be used for
either l2 or l3, although it won't support vpls PE.  It's a dual 20G
channel card, which is why it will only run on slots 9-13 on the 6513 -
slots 1-6 are single-channel only, so it will not work there.

There are some limitations: the buffers are tiny so you should expect
packet drops if your traffic is bursty.  Also, although hardware
revision 3.0 and greater has enough i2c hardware to handle DDM, it's not
enabled in any software version, so you get zero visibility into light
levels on any of the ports.  This may not be a problem for you, but it's
worth being aware of.

Nick