In an ethernet LAN, all hosts on that subnet contend for access to the
ethernet bus. No matter what the physical topology, the logical topology is
that of a bus. Remember the original ethernet: a long coaxial cable with
taps along the way that connect to hosts. In that configuration, it's easy
to see the bus topology. You might never see that type of network in your
life which may be why this is confusing.
A hub is a device that aggregates hosts on a contention network, and it
physically creates a star topology, not a ring. However, it acts exactly as
if there were still that one long cable with hosts attached along the way.
A token ring network operates quite differently. A MAU with hosts attached
may look just like a hub with hosts attached, but the similarities are
cosmetic only. A TR network is not contention-based like ethernet. In
ethernet, all hosts "compete" for access. In a TR, however, no competition
is necessary--all hosts must wait their turn!
A TR network is also a physical star, like the modern ethernet LAN, but to
access the network, hosts must wait for an unused token to pass. If they
have something to transmit, they grab the token, attach a packet it to it,
and send it along its way. Eventually, the token continues to pass by each
host as if they were physically attached in a circle, each one getting a
shot at the token.
To sum up, it's important to keep in mind the differences between physical
topology and logical topology. I've over-simplified some of this to make it
a little more clear. You'd do well to read up some more on this to clear up
things that I've left unsaid.
HTH,
John Neiberger
> I was reading about network topology and they say that an example of bus
topology is Ethernet network. Wouldn't ethernet network be a ring topology
due to
> hub/switch environment?
>
> Please correct me where I am wrong.
>
> Thank you in advance.
>
> Oscar Rau
> [EMAIL PROTECTED]
>
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