[f-nsp] Transceiver "not supported" on ICX7750 in Breakout-Mode

[Eldon Koyle]

On May 19, 2016 7:45 AM, "Franz Georg Köhler" <lists at openunix.de> wrote:
>
> Am 18.05.16 um 16:12 schrieb ekoyle+puck.nether.net at gmail.com (Eldon
Koyle):
>
>> You can run 40G without stacking on the 7750, although you may need to
>> change some default stacking settings.  What code version are you
running?
>
>
> Hello,
> we are running 08040a.
>
> The Brocade manual says:
>>
>> In release 8.0.30, the breakout support on the 40G interfaces will be
supported on a standalone mode only. Breakout ports will not be supported
with stacking configuration.
>
>
http://www.brocade.com/content/html/en/feature-guide/brocade-icx7750-breakout-ports-fg/GUID-459FAE8C-4013-4E6C-9AE9-BEE4977BA22C.html
>
> But this was just a side note as we did not expect such a limitation and
were suprised when we discovered that information in the manual.
>

So you wanted to create a stack over a breakout cable?  I suspect there are
some hardware or software limitations that make that difficult for brocade
to implement.

>
>
>> I suspect support for third-party breakout cables is very limited.
>
>
> Is there any difference on the switch side if there is a breakout cacble
connected? Is there such a thing like hardware support for breakout cables?
>
> Until now, I was under the impression that a 40G port is just an
aggregated 4x10G port and the switch just needs to deactivate the
aggregation in order to break out? Am I wrong?
>
>

Although at the physical layer a 40G port  is 4 10G channels, there may be
some shared resources for the port that don't act separately, so the PHY
and the software both need to support breakout cables.

One other thing to note, I have found support for 3rd party twinax cables
to be abysmal (it will try to use them, but there may be issues where a
port shows up even though the remote end is disabled; also high error
rates).

-- 
Eldon
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