Comparison of LANs

CSMA/CD:

1. Advantages:
   1. One of the earliest LAN protocol, has a very large installation base, cheap hardwares (around $100per port). Much experience and software exist for supporting the network.
   2. Removing and adding new nodes doesn't bring the whole network down, making maintenance a piece of cake;
   3. Very low delay under light network load;
   4. Maximum speed a whopping 10!
2. Disadvantages:
   1. Low efficiency at high load;
   2. No guarantee on delay (could be infinity);
   3. No priority schemes;
   4. Network is limited to around 2.5 in cable length;
   5. Maximum speed is a meager 10.
   6. Not suited for fiber implementation;

Token Bus:

1. Advantages:
   1. Not much hardware requirement (cheap);
   2. More deterministic;
   3. Have priorities;
   4. Very high efficiency at high load;
   5. etc.

2. Disadvantages:
   1. Protocol is very complex;
   2. Large delay at low load (due to token overhead);
   3. Not suited for fiber implementation;

Token Ring:

1. Advantages:
   1. Not much hardware requirement (consists of cheap point to point links);
   2. More deterministic;
   3. Have priorities;
   4. Very high efficiency at high load;
   5. etc.

2. Disadvantages:
   1. Protocol is very complex;
   2. Large delay at low load (due to token overhead);
   3. Needs central monitoring station (if that station fails but continue to impersonate normal condition, the network will certainly crash);

FDDI:

1. Advantages:
   1. Fast;
   2. Can cover much larger geographical area;
   3. Can reconfig if the rings broke or if a station is down;
   4. Can carry time guaranteed traffic;
   5. More deterministic;
   6. Have priorities;
   7. Very high efficiency at high load;

2. Disadvantages:
   1. Still quite expensive;
   2. Protocol is very complex;
   3. Large delay at low load (due to token overhead);