Ethernet names...

[Grant Taylor]

On 10/04/2018 12:16 PM, Paul Koning via cctalk wrote:
> I had to look up SQE.  http://www.ethermanage.com/ethernet/sqe/sqe.html 
> It's 802-speak for the same signal.

I agree that it's the same concept and function.  Though the link you 
shared states that there is some timing difference between D.I.X.'s 
"Collision Presence Test" (CPT) and IEEE's 802.3 "Signal Quality Error" 
(SQE).

> That page says you have to turn it off for the transceiver connected to 
> an 802.3 repeater, but it should be on in all other cases.  Sounds like 
> the 802.3 people got the transceiver design wrong and that rule is a 
> workaround.  There certainly is no similar rule in the Ethernet spec, 
> and repeaters are definitely part of that spec.

Given that CPT / SQE / HB are between the transceiver and the host NIC, 
and NOT between the transceiver and the Ethernet, IMHO it makes sense 
that CPT / SQE / HB should not be used with a repeater.  After all, a 
repeater is going between two (or more?) Ethernet segments.

As such, I don't think it's a problem with the specification or design 
of transceivers.

I think the CPT / SQE / HB are in some ways a feedback loop between the 
transceiver and the NIC to test the collision detection circuitry in the 
NIC.



-- 
Grant. . . .
unix || die