4 Oct
2018
4 Oct
'18
2:36 p.m.
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