28 May
2023
28 May
'23
10:46 a.m.
FYI: The Ethernet standards dropped support for half duplex connections a few years back,
so that if you have something that depends on half duplex links a recent Ethernet switch
might not support it.
28 May
28 May
12:01 p.m.
I found that out the hard way recently when I acquired my AS/400 and the
10Mb/s card for it. It did not like talking to my 10/100/1000 switch at all.
And of course I had recently gotten rid of my old 10Mb/s hub I had been
saving for a couple of decades... Had to resort to eBay for an ancient hub.
On Sun, May 28, 2023 at 2:09 PM Craig Ruff via cctalk <cctalk(a)classiccmp.org>
wrote:
FYI: The Ethernet standards dropped support for half
duplex connections a
few years back, so that if you have something that depends on half duplex
links a recent Ethernet switch might not support it.
1:18 p.m.
On May 28, 2023, at 1:46 PM, Craig Ruff via cctalk
<cctalk(a)classiccmp.org> wrote:
FYI: The Ethernet standards dropped support for half duplex connections a few years back,
so that if you have something that depends on half duplex links a recent Ethernet switch
might not support it.
Dropped support for it on 10 Mb links? That seems like a crazy change to make. I know it
was defined but basically unused at higher speeds.
paul
1:58 p.m.
On May 28, 2023, at 14:18, Paul Koning
<paulkoning(a)comcast.net> wrote:
Dropped support for it on 10 Mb links? That seems like a crazy change to make. I know
it was defined but basically unused at higher speeds.
No just the half duplex part of the standard. The 10 Mb/s full duplex links are still
supported.
4:30 p.m.
Best thing to do is keep an old 10mbit switch or hub around with 100mbit or gigabit
uplink. Second best thing is to have a router that will talk 10mbit half duplex.
I've also found some poorly behaved stuff that won't autonegotiate duplex even
with older switches, like my 3Com SuperStack II. Asante SCSI Ethernet adapters come to
mind. Had to set the duplex manually on the switch.
Along those lines, 10gig copper interfaces often don't want to talk to 100mbit ports!
Found that out when we had a switch fail and stuck an older 10/100 switch in just to get
back up and running.
Thanks,
Jonathan
------- Original Message -------
On Sunday, May 28th, 2023 at 13:46, Craig Ruff via cctalk <cctalk(a)classiccmp.org>
wrote:
FYI: The Ethernet standards dropped support for half duplex connections a few years back,
so that if you have something that depends on half duplex links a recent Ethernet switch
might not support it.
29 May
29 May
11:03 a.m.
On 29/05/2023 00:30, Jonathan Chapman via cctalk wrote
Along those lines, 10gig copper interfaces often
don't want to talk to 100mbit ports! Found that out when we had a switch fail and
stuck an older 10/100 switch in just to get back up and running.
I believe the 10Gb standard specifically prohibits autonegotiation, so
10G should not drop down to 1G or 100Mb/s.
Antonio
--
Antonio Carlini
antonio(a)acarlini.com
4:08 p.m.
On 5/29/23 14:03, Antonio Carlini via cctalk wrote:
I believe the 10Gb standard specifically prohibits autonegotiation, so
10G should not drop down to 1G or 100Mb/s.
Is that maybe only applicable to the 10G standards for optical fibre?
According to Wikipedia 10GBASE-T supports autonegotiation:
"10GBASE-T cable infrastructure can also be used for 1000BASE-T allowing
a gradual upgrade from 1000BASE-T using autonegotiation to select which
speed is used."
https://en.wikipedia.org/wiki/10_Gigabit_Ethernet#10GBASE-T
"The autonegotiation specification was improved in the 1998 release of
IEEE 802.3. This was followed by the release of the IEEE 802.3ab Gigabit
Ethernet standard in 1999 which specified mandatory autonegotiation for
1000BASE-T. Autonegotiation is also mandatory for 1000BASE-TX and
10GBASE-T implementations."
https://en.wikipedia.org/wiki/Autonegotiation#Standardization_and_interoper…
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participants (6)
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Antonio Carlini -
Craig Ruff -
John-Paul Stewart -
Jonathan Chapman -
Paul Koning -
Peter Ekstrom