Ethernet names...

[Paul Koning]

> On Oct 4, 2018, at 1:07 PM, Eric Smith via cctalk <cctalk at classiccmp.org> wrote:
> 
> On Tue, Oct 2, 2018 at 10:55 PM Grant Taylor via cctalk <
> cctalk at classiccmp.org> wrote:
> 
>> On 10/02/2018 05:27 PM, Eric Smith via cctalk wrote:
>>> 3 Mbps Ethernet is _NOT_ Ethernet I. Both Ethernet I and II were 10 Mbps
>>> DIX standards, with II having only minor differences from I.
>> 
>> Okay.  Thank you for the correction ~> clarification.
>> 
>> Now I'll keep an eye out (but not quite search for) the differences
>> between Ethernet (I) and Ethernet II
> 
> 
> The Ethernet I and II standards are available from Bitsavers:
>    http://bitsavers.trailing-edge.com/pdf/xerox/ethernet/
> 
> From the preface of _The Ethernet_ Version 2.0:
> Version 2.0 of the Ethernet specification reflects the experience of the
> three corporations in designing equipment to the Version 1.0 specification.
> Version 2.0 includes network management functions and better defines the
> details of the physical channel signalling. Version 2.0 is upward
> compatible with Version 1.0. Equipment designed to the two specifications
> is interoperable.

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).

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. 

	paul