Common Access Protocols:

Standards:

Ethernet II:

Digital/Intel/Xerox standard (also promulgated by IEEE); probably the most common,

Even though there are no standards explicitly promulgated, EthernetII has been extended to fast and gigabit standards

802.3:

International Ethernet Standard

Cat 3 UTP cable

802.3u:

Fast (100Mbps) E'net

Cat 5 UTP cable

802.3z:

Gigabit (1000 Mbps) E'net (mostly over fiber, 1000BASE-CX specifies short-haul copper for wiring closets)

802.3ab:

Gigabit (1000 Mbps) E'net over UTP wire (various 1000BASE-T standards)

Cat 5e, Cat 6, or Cat 7

See:

http://www.cableu.net/wiretech/cat5twst.htm

http://www.globalsources.com/MAGAZINE/EC/0202W2/LANC02.HTM

http://www.globaltec.com/catext100.html

http://www.cableu.net/

802.5:

Standardized Token Ring

802.11:

Wireless at a maximum of 2 Mbps

802.11a:

Wireless at a maximum od 54 Mbps for Asynchronous Transfer Mode (ATM)

802.11b:

Wireless at a maximum of 11 Mbps

802.12:

VG-AnyLAN: HP-fostered standard, never widely implemented

FDDI:

Fiber Distributed Data Interface, 100 Mbps token-passing standard, formerrly widely used for corporate backbone

Uses primarily fiber-optic cable (longer distances for campus backbone), dual counter-rotating ring topology, automatic ring repair for single failures

Stations on either side of a failure detect it and wrap the signal back on the other ring

MAC addresses:

A six-byte address assigned to every node on the network

First three bytes administered by IEEE and assigned for a fee to a vendor

Second three bytes administered by vendor and assigned sequentially to devices as manufactured

Entire MAC address is "burned into" a ROM on the device, the "burned-in address" or BIA

See the following for MAC identifier tools:

http://standards.ieee.org/regauth/oui/index.shtml

http://coffer.com/mac_find/

Note that large enterprise devices may have a block of MAC addresses assigned to it

This block may be over a thousand addresses in size

Special cases about the MAC address of the network interface card (NIC):

Group/Individual bit

First bit in the MAC address when it appears on the wire, allows multiple NICs to receive the same frame

Global/Local bit

Second bit of the MAC address when it appears on the wire, identifies whether the administrator has modified the MAC,

mostly token ring, however, see broadcast below

Unicast

One station sends a packet to another single station

Multicast

One station sends a packet to multiple other stations, E'net MAC starts with 01-00-5E,

last three bytes of M'cast MAC derived from special m'cast address

Broadcast

One station sends a packet to all other stations on the wire, MAC = FF-FF-FF-FF-FF-FF

a special case of the m'cast frame (all bits are 1, so bit 1 must be set, so it is an m'cast frame)

Canonical/non-Canonical representation:

Canonical representation the least-significant bit of each byte goes onto the wire first (little-endian)

non-Canonical representation the most significant bit of each byte goes onto the wire first (big-endian)