[c-nsp] loop guard still useful?

Saku Ytti saku at ytti.fi
Mon Jan 18 14:40:18 EST 2016

On 18 January 2016 at 21:22, Lee <ler762 at gmail.com> wrote:
> so apparently 100Mb fiber doesn't have that problem any more.  I don't
> think 1 or 10Gb fiber ever did..

I believe if you implement autonego, you have to implement RFI. But
I'm not 100% sure about that.

IEEE 802.3 standard isn't exactly easiest standard to read. But there
are quite many surprising goodies in autonego which are usually not
known, not just RFI. Autonego can assert when link is configured
operationally down, meaning far-end could produce syslog information
about link going down, because far end was configured down, which
would help lot with troubleshooting, when you can know if far-side is
intentionally down or not.
My understanding of reading hardware specs is that this feature is
even supported in typical PHY, however I've NEVER seen software using
this feature.

I'd love recommendation on good, modern book about 802.3, with
irrelevant bits not addressed, relevant bit discussed and practical
view offered on how things are actually implemented in modern, common
hardware. So far any book I've read, does not even discuss autonego in
satisfactory detail, and I fear what else am I missing due to my
unwillingness to weed through 802.3.


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