Networking Fundamentals

Lecture 3

Ethernet Protocol

IEEE 802 LAN Standards

Additional LAN Standards

Ethernet Milestones

Developed during the mid- 1970 at Xerox

Palo Alto Research Center (Metcalfe)

Later refinement by DEC, Intel and Xerox

(DIX standard )

Became IEEE 802.3 in 1985

Different frame format between Ethernet and

IEEE 802.3

Ethernet Basics

The basics Ethernet Bus

Ethernet Basics

Collisions

Ethernet Basics Cont.

Medium Access Method

Carrier Sense Multiple Access with Collision

Detection CSMA/CD

Ethernet Frame Transmission

Ethernet Frame Reception

CSMA/CD

Common Types of Ethernet

10Base2 (Thinnet Coax) Ethernet

10BaseT (Twisted-Pair) Ethernet

100BaseT (Twisted-Pair) Ethernet

100BaseFL (Fiber-optic) Ethernet

Ethernet Frame

10BaseT Ethernet

Uses UTP cable

Wired in a Star

Connection to hubs/switches and LAN card is

made with RJ-45 connector

LAN Standards

IEEE 802

802.3 (Ethernet)

802.4 (Token bus)

802.5 (Token ring)

802.11 (Wireless LAN)

ANSI standards

FDDI

IEEE LAN Standards

IEEE: Institute of Electrical and Electronic Engineers

IEEE create standards for computer and communications

IEEE 802 series of standards for LAN technologies

IEEE defined several access methods CSMA/CD

Token passing

Demand priority

Protocol Architecture

Lower layers of OSI model

IEEE 802 reference model

LAN layered protocol architecture Physical (topologies)

Media access control

Logical Link Control

All IEEE 802.x have the same LLC sublayer

MAC sublayer has very close relationship with the characteristics of physical medium and the topology of network

IEEE 802 versus OSI

Layer 7

Layer 6

Layer 5

Layer 4

Layer 3

Data Link

Physical Physical

Logic Link Control

Media Access Control

Upper Layers

Protocols

Scope of IEEE 802 Standards

OSI Reference Model

IEEE 802 Reference Model

IEEE 802

802.1 Architecture and Internet

802.2 Logical Link Control

802.3 Ethernet

802.4 Token Bus

802.11 Wireless

LAN Physical Layer

Data Link Layer

MAC

LLC

802.14 Cable Modem

802 Layers - Physical

Signal encoding/decoding

Preamble generation/removal (for

synchronization)

Bit transmission/reception

Transmission medium and topology

802 Layers – MAC and LLC

OSI layer 2 (Data Link) is divided into two in

802

Logical Link Control (LLC) layer

Medium Access Control (MAC) layer

802 Layers - MAC

Assembly of data into frame with address and

error detection fields (for transmission)

Disassembly of frame (on reception)

Address recognition

Error detection

Govern access to transmission medium

802 Layers - LLC

LLC is the upper sub-layer of the OSI data

link layer.

Interface to higher levels

The LLC is the same for the various physical

media (such as Ethernet, token ring, WLAN).

IEEE 802 Protocols

802.1 specifies general procedures that all

LANs follows and how to interconnect with

higher layers.

802.2 relates to end-to-end logical links:

Logical Link Control LLC

802.3 - 802.14 are responsible for: Medium Access Control

Physical Layer Implementation

IEEE 802.2

Used by all standards in IEEE 802 series

Used by FDDI ( FDDI is not IEEE standard)

Logical Link Control LLC

IEEE 802.3

Ethernet is a predecessor of IEEE802.3

Ethernet don’t comply with 802.2

Wiring standards 10base2 (thin coax)

10base5 (thick coax)

10baseT (UTP)

IEEE 802.3 and Ethernet supports MAC address and same physical layer

Access method CSMA/CD (broadcast)

Create heavy traffic

Topology: Bus

Star

Cable support : UTP, Coax and fiber optic

MAC Address

Unique address

Hardware address

Burned on the NIC by the manufacturer

Used to identify the computer on the network

Use 12 hexadecimal digits (48 bits)

Physical Address. . . . . . . . . : 00-22-68-15-A4-2F

First 24 bits are vendor code

Last 24 bits are interface serial number

IEEE 802.3u Fast Ethernet

Higher speed 100Mbps

Access method CSMA/CD

Wiring standards

100baseTX

100baseT4

100baseFX

Topology: Star

Cable support: UTP and fiber optic

IEEE 802.3z and 802.3ab Gigabit Ethernet Used in network backbone

Data rate 1000Mbps

Access method CSMA/CD

802.3z use copper cable and fiber optic cable

802.3ab use cat5 UTP

Wiring standards

1000baseT (cat5 UTP)

1000baseCX (copper cable)

1000baseSX (fiber optic cable)

1000baseLX (fiber optic cable)

IEEE 802.5 Token Ring Token ring was initially developed by IBM

802.5 standard comply with IBM token ring standard

Access method: Token passing

Token is passed in one direction across the network

Data rates 4 or 16 Mbps

May use star topology using MAU Multi-station access unit

MAU can bypass faulty nodes on the ring

Additional LAN Standards

Other LAN standards NOT included in IEEE

802 project

Apple LocalTalk

Fiber Distributed Data Interface

FDDI

FDDI

ANSI Standard

American National Standards Institute

Access method: Token passing

Use 2 counter-rotating rings for redundancy

FDDI can be classified as MAN

Distance up to 200Km

LAN Access Methods Summary

IEEE802.3

Ethernet

CSMA/CD

IEEE802.11

CSMA/CA

Token Ring

IEEE802.5

FDDI

Token passing

Thank you