[rescue] AUI duplex [was Re: New SPARCStation 10 owner, needs help with some issues though.]

[Carl R. Friend]

On 02/06/2016 02:14 PM, Mouse wrote:
>> Once some of the snow melts, I'll see if I can scavenge up enough
>> bits to commission a test length of 10-Base-5 (good old-fashioned
>> "Etherhose") and see what various machines can do with it.
>
> I'll be interested.  I no longer have any 10base5 stuff, though I could
> probably set up a small 10base2 network.

    10-Base-2 is as valid as 10-Base-5.  The only difference is the
physical media (coax cable) involved and tapping technique.  One can
hot-tap 10-Base-5 carefully; this is not possible with 10-Base-2 (aka
"Cheapernet").

> Would it make you feel better if I used two machines connected directly
> with a crossover 10baseT cable? :-)  (I have the pieces to put together
> a 10base2 network, but much of them are I-don't-know-where in storage.)

    Not a lick.  Just *perhaps* two machines on 10-Base-T both talking
to a hub and with a critical eye on the collision light...

>> Recall that before transmitting, a machine had to first listen to see
>> if it was safe to "talk".
>
> ...and then, if it sounded quiet, transmit channel seizure and watch
> for collisions.

    Nah, they just started yapping if the wire was clean.  Collisions
were detected "during the act" at which point everybody'd back off
for a random amount of time and then start listening again.  The
random backoff was to deal with distance-related issues.

> Connection-oriented?  Are you talking about flow labeling?  That's
> relatively recent, isn't it?

    Not at all.  Switches are aware of what MAC address is associated
with what port, so inbound packets from a given MAC address are
crossbar-switched to the destination MAC address.  (Or, at least
layer-two switches are, which is "good enough" unless one wants to
get into layer-three routing.)


-- 
+------------------------------------------------+---------------------+
| Carl Richard Friend (UNIX Sysadmin)            | Boylston            |
| Minicomputer Collector / Enthusiast            | Massachusetts, USA  |
| mailto:crfriend at rcn.com                        +---------------------+
| http://users.rcn.com/crfriend/museum           | ICBM: 42:20N 71:43W |
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