[j-nsp] MIC-3D-4XGE-XFP in a MX104?

[Saku Ytti]

Hey Tim,

Simple answer, not possible, as you need PHY and 4x10GE does not have
one, while 2x10GE does have one.





Longer answer.

This is quite interesting question. I'll first explain why the answer
is decidedly 'not possible on MX80'. Trio MQ WAN side can operate as
SERDES or 4x10GE PHY. which can drive XFP ports directly. On MPC cards
and  MX80 the front-plate 4x10G use the PHYs on MQ. Rest of the ports
on MX80vsit on 'fabric' side, which can only run as SERDES. To attach
any more ports than 4x10GE on-boardvports to MX80, you need chip to
talk to the fabric side, which is SERDES only, you need some chip to
interface with SERDES and offer PHY (IX chip.

So 4x10GE MIC is simpler, stupider (And lower BOM) than 2x10GE MIC, as
it does not have IX chip at all, as PHY is driven by MQ. Where as
2x10GE MIC has IX chip and PHY. This allows us to put the 2x10GE
interfaces on the 'fabric' side of the MQ.

Now for reasons I don't fully understand MQ PHY actually cannot drive
SFP+, only XFP. So MX104 is using IX chip and external PHY to drive
the on-board SFP+. Technically it /could/ sit on 'fabric' side, and
you could wire the box so that on WAN side you can attach 4x10GE XFP
MIC. However I'm almost certain that the on-chassis SFP+ ports are
still connected on the WAN side, so reason why it wouldn't never work
on MX104 is same as MX80, no PHY on the 4x10GE XFP MIC.



On 24 November 2017 at 19:20, Tim St. Pierre <tim at communicatefreely.net> wrote:
> Hello,
>
> As anyone ever put a 4XGE MIC card in a MX104?  Only the 2XGE card is
> supported obviously, but I'm curious to know what would happen if someone
> did?  Is it just oversubscribed?  Would it not work at all?
>
> -Tim
>
> --
>
> --
> Tim St. Pierre
> System Operator
> Communicate Freely
> 289-225-1220 x5101
>
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-- 
  ++ytti