MAN: A metropolitan area network (MAN) is larger than a LAN. It normally covers a
city-sized area and reaches a size several kilometers.
WAN: A wide area network (WAN) includes all networks. A WAN interconnects LASs
that may be located in different countries.
Appendix B
Copper Pairs
1. Most LANs employing copper wires use two pairs: one pair in each direction and all
twisted-pair are baseband.
2. Pairs must be twisted. This minimizes the EMI interface and radiation.
3. Pairs must be shielded - IBM type 1 and 2 use shielded pairs.
4. Typical interface - unshielded twisted pair (85-115 ohms at 10mhz) and shielded
twisted pair (150 ohms).
5. For UTP, RJ45, 8-pin modular telephone plugs dominate - 10BaseT standard
specifies them.
Coaxial Cable
Coaxial cable is used for both baseband and broadband LANs
1. Independence - the independence of coaxial cable is not based on size. That means, for
example, that bib cables do not necessarily have a low impedance.
2. Three common values of impedance - 50 ohms (for baseband Ethernet/802.3 LANs),
75 ohms (for broadband LANs/801.4) and 93 ohms (for ARCnet LANs)
3. EMI, radiation and bandwidth/bit rate
• EMI susceptibly and radiation are lower than TP.
• Conventional bandwidth is greater than 400mhz. It is usually limited by the
attached equipment.
• Data bit:10Mbps
4. Advantage of using optical fiber are:
• Security: No radiation. Avoids tapping.
• EMI: Not susceptible to electromagnetic interference.
Appendix C
Ethernet Comparison Chart
