I'm coming into this discussion late, but without any context I think it's
pretty clear that Token Ring is a logical ring. Each station acts like a
bit repeater, taking in bits from the upstream neighbor and sending bits to
the downstream neighbor. When sending a frame, a station waits for its own
bits to come back around. The sender strips its bits from the ring to keep
them from rotating forever. Token Ring requires a closed loop system for
this to work correctly.
With a logical bus, on the other hand, a station sends its bits and the
bits radiate out to both ends of the line. Terminators at the end of the
physical bus stop the frame from bouncing back. Each station hears the bits
without any need for relaying of bits from upstream to downstream. The
sender never sees its bits come back (unless there's a problem).
Token Ring is cabled as a star. Each device connects to a MAU. Inside the
MAU, ring in and ring out either loop to each other or connect other MAUs.
If you take it all apart, it's still a ring. But from the human point of
view, we cable the ring as a star, not a circle of connected computers.
We would have to ask Lou Rossi what he meant by his statement that Token
Ring is a logical bus. It's either a typo or he has some unique way of
explaining things.
Priscilla
At 08:29 AM 2/26/01, Nigel van Tura wrote:
>But Bradley
>
>If we connect all to the MAU as a central hub then it becomes a physical
>star and a logical ring inside the MAU.
>
>Or what ?
>Nigel van Tura
>
>-----Original Message-----
>From: Bradley J. Wilson [mailto:[EMAIL PROTECTED]]
>Sent: 24 February 2001 01:50
>To: cisco
>Subject: Lou Rossi's Token Ring paper
>
>
>I'm sitting here reading Lou Rossi's Token Ring paper, and right off the bat
>I have a question:
>
>He says that token ring is "a physical ring and a logical bus" - but isn't
>this backward? Isn't it a physical bus and a logical ring? We're not
>physically connecting stations together in a ring - they're all plugged into
>a MAU and the "ring" is a logical entity inside the MAU, isn't it?
>
>Thanks in advance,
>
>BJ
________________________
Priscilla Oppenheimer
http://www.priscilla.com
_________________________________
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
