Ethernet names...

Paul Koning paulkoning at comcast.net
Thu Oct 4 12:39:22 CDT 2018



> On Oct 4, 2018, at 1:30 PM, Grant Taylor via cctalk <cctalk at classiccmp.org> wrote:
> 
> On 10/04/2018 11:26 AM, Paul Koning via cctalk wrote:
>> That's sort of accurate.  A quick look shows some key differences: V2 adds the "collision presence test" -- verifying the collision detect signal is working.  There is also the "jabber timer" -- a watchdog timeout that stops excessively long frames.  And V2 introduces the loopback protocol (protocol type 90-00).
> 
> That mostly sounds like the frame formats are the same on the wire and that the differences are in the protocols that use said frame.
> 
>> The collision presence test is somewhat of an interoperability issue: if you attach a V1 transceiver to a V2 NIC, the NIC would complain on every transmit that it didn't get the collision test signal.
> 
> That makes me wonder about the "heartbeat" switch that I see on older AUI transceivers.

Yes, I think that's the collision test.  So in the OFF position you have a V1 compatible transceiver, ON is needed for V2.

	paul



More information about the cctalk mailing list