what are the networking topologies?

Answer 1

star, ring, point to point, broadcast , mesh, hierarchy, DAG (Directed acyclic graph).

You can probably think up some more if you like.

802.16/WiMax is a star topology in as much as it is made of point to point links at the MAC service level where one end of the links all meet at the base station. This is similar to a cat5 ethernet switch (more correctly named a multiport relay in 802.1D).

Modern cat 5 ethernet (at the mac layer) is point to point. See above for how ethernet switches bind cat5 networks into a star topology and below for how ethernet switches bind them into a mesh topology.

Older coax ethernet was broadcast resulting from its multi drop physical layer.

802.11 is a bit odd. It's closest to a broadcast topology but deviates from that model due to the unreliability of the medium.

Token ring is a ring. 802.17 RPR is a dual ring.

Mesh is what the internet is, at least as far as the basic OSPF model directs routing. IEEE 802 bridged networks are meshes as well, which is why I emphasized the "at the MAC layer" of ethernet's broadcast and point to point topology.

Hierarchical networks are common in embedded real time control because it fits nicely with the wiring going back to a central controller and having intermediate nodes that both perform embedded functions and forward data.

Arguably, the spanning tree protocol of 802.1D that applies to IEEE 802 bridged networks is a hierarchy, but later amendments have complicated the model.

The 802.16j mobile relay amendment may or may not yield a DAG depending on what they do.

Answer 2

Star, ring, bus, then you can Mesh them. Those are the physical topologies, then you can work up point-point etc...

In fact, Star is a bit questionable as a topology, Ethernet and hub certainly look like a star on paper, but it is really a bus if you unscrew whatever hub and explore the circuitry inside.