IEEE 802 standards

A set of network standards developed by the IEEE. They include:

IEEE 802.1: Standards related to network management.

IEEE 802.2: General standard for the data link layer in the OSI Reference Model. The IEEE divides this layer into two sublayers:

The logical link control (LLC) layer, and,

The media access control (MAC) layer. The MAC layer varies for different network types and is defined by standards IEEE 802.3 through IEEE 802.5.

IEEE 802.3: Defines the MAC layer for bus networks that use CSMA/CD. This is the basis of the Ethernet standard.

IEEE 802.4: Defines the MAC layer for bus networks that use a token-passing mechanism (token bus networks).

IEEE 802.5: Defines the MAC layer for token-ring networks.

IEEE 802.6: Standard for Metropolitan Area Networks (MANs).

Ethernet standard is ISO/IEC 8802-3 (ANSI/IEEE Std 802.3)

Fast Ethernet standard is IEEE Std 802.3u-1995

Token Ring LAN standard is ISO/IEC 8802-5 (ANSI/IEEE Std 802.5)

Wireless LAN is IEEE Std 802.11

100BASE-T standard is IEEE Std 802.3u-1995

Here is a list of acronyms and buzzwords that the IEEE Standards Department has put together to help you identify an IEEE standard or a standard belonging to another standards-developing organization. The list is in alphabetical order according to the buzzword. "IEEE PXXX" refers to an unapproved IEEE Standards project; "IEEE Std XXX-19XX" refers to an approved standard.

Information from https://www.ieee.org.

Formats of IEEE 802 MAC Frames, from Telecommunications Protocols and Design, by John D. Spragins. All lengths are in bytes.

CSMA/CD

Preamble	SD	Dest. Addr.	Source Addr.	Length	Info.	(Pad)	FCS
7	1	2 or 6	2 or 6	2	Variable		4

Token Bus

Preamble	SD	FC	Dest. Addr.	Source Addr.	Info.	FCS	ED
1 or more	1	1	2 or 6	2 or 6	Variable	4	1

Token

SD	AC	ED
1	1	1

LLC Frame

SD	AC	FC	Dest. Addr.	Source Addr.	Info.	FCS	ED	FS
1	1	1	2 or 6	2 or 6	Variable	4	1	1

Preamble:Bit pattern for stabilization and synchronization

SD (Start Delimiter): Bit pattern indicating the start of a frame.For the token ring and token bus, it includes non-data bits, that is, signaling patterns not in the normal signal set, so a SD is easy to recognize.

FC (Frame Control): Used in token ring and token bus networks to distinguish between types of frames, including MAC frames and LLC frames.

AC (Access Control): Used in token ring to control access according to priority and reservation algorithms.

Destination Address and Source Address:Address of destination and source, respectively.

Length:Length of data portion of frame in bytes; used only in CSMA/CD.

Information:User data.For LLC frames this is LLC data.� For CSMA/CD frames, etra pad characters fill out this subframe.If the total frame length is less than a specified minimum value (normally 512 bits).

FCS (Frame Check Sequence): A 32-bit frame check sequence derived from a polynomial code based on CRC-32.

ED (End Delimiter):A sequence of bits indicating the end of a frame. Used in token bus and ring networks, with non-data bits to make ED easy to recognize. (Not needed in CSMA/CD because of length field).

FS (Frame Status):A byte containing status bits, such as an address recognized and a frame copied bit.Used in token ring LLC data frames.

Address Fields for IEEE 802 MAC Protocols (numbers in bits):

Two-Byte Address Field

I/G
1	15

I/G:Individual address or group address

Six-Byte Address Field

I/G	U/L
1	1	15

I/G:Individual address or group address

U/L:addresses assigned on a universal basis or by local authority

IEEE 802.2 LLC Protocol Data Unit

A LLC PDU is the information field of a MAC frame.

Format (numbers in bytes)

DSAP Addr.	SSAP Addr.	Control	Info.
1	1	1 or 2	Variable

DSAP:Destination service access point

SSAP:Source service access point

IEEE 802.2 LLC Address Fields

I/G

C/R

DSAP Addr. Field

SSAP Addr. Field

I/G:Individual address or group address

C/R:Command or Response bit