FDDI
====

The FDDI_MAC simple module is an accurate FDDI MAC simulation. Based on 
FDDI_MAC, a number of network nodes are put together: FDDI station, router, 
network analyzer.

There is a general FDDI network model:

  - FDDIRing is a simple FDDI ring of identical nodes (FDDIStations). 
    The stations are connected in the form of a ring, plus each of them is 
    connected to a 'stat' module.

  - FDDIRing can be simulated using the FDDI1 network.

Other ring models are models of the former FDDI backbone of the Technical 
University of Budapest:

  - TUBSRing is the model if the Southern FDDI ring. From the dual attached
    ring only one direction is modelled; all the stations are modelled just
    with SAS.

  - TUBNRing: is the model if the Northern FDDI ring. The stations are
    connected in ring topology, plus there are some concentrators. From the
    dual attached ring only one direction is modelled; all the stations are
    modeled just with SAS, and all the concentrators are modelled with
    SAC-4.

The topology (the stations, the order of stations, the cable lengths) is
real. The offered load of the ring is generated from histograms, stored in
files in the load/ directory. The traffic is also based on reality: the
files were generated from measurements made on the live network with a
Sniffer.

The NRing network can be used to model the Northern ring alone, but it is 
more interesting to simulate the two rings together.

In real life, the two FDDI rings (Southern Ring and Northern Ring)
connected by a router. The traffic flowing through the router can be
simulated packet-by-packet or statistically:

  - the TUB_wired module (TUBw network) simulates each packet transmission;

  - with the TUB_SSM module (TUBs network), the two rings are interconnected
    by Statistical Synchronisation interfaces, so only the statistical
    characteristics of the packet flow (frame length histograms, etc.) are 
    exchanged between the two rings.

