1. LAN TECHNOLOGIES
S.T.D.Maduranga

2. • Ethernet
• FIBER DISTRIBUTED DATA INTERFACE (FDDI)
• Token Ring
Technology Options

3. Our Focus is Ethernet
• History
• Developed by Bob Metcalfe and others at Xerox PARC
in mid-1970s
• Roots in Aloha packet-radio network
• Standardized by Xerox, DEC, and Intel in 1978
• LAN standards define MAC and physical layer
connectivity
• IEEE 802.3 (CSMA/CD - Ethernet) standard – originally
2Mbps
• IEEE 802.3u standard for 100Mbps Ethernet
• IEEE 802.3z standard for 1,000Mbps Ethernet

4. Ethernet Standard Defines Physical Layer
Metcalfe’s original
Ethernet Sketch
802.3 standard defines both MAC and physical layer
details

5. Ethernet
• 10 Base 5 (Thicknet) (Bus
Topology)
• 10 Base 2 (Thinnet) (Bus
Topology)
• 10 Base T (UTP) (Star/Tree
Topology)
• 10 Base FL (Fiber) (Star/Tree
Topology)

6. Ethernet Technologies: 10Base2
10: 10Mbps; 2: under 185 (~200) meters cable length
Thin coaxial cable in a bus topology
Repeaters used to connect multiple segments
Repeater repeats bits it hears on one interface to its other interfaces: physical layer device only!

7. 10BaseT and 100BaseT
• 10/100 Mbps rate
• T stands for Twisted Pair
• Hub(s) connected by twisted pair facilitate “star topology”
• Distance of any node to hub must be < 100M

8. Fast Ethernet
• 100 Mbps bandwidth
• Uses same CSMA/CD media access protocol and packet format as in Ethernet.
• 100BaseTX (UTP) and 100BaseFX (Fiber) standards
• Physical media :-
• 100 BaseTX - UTP Cat 5e
• 100 BaseFX - Multimode / Singlemode Fiber
• Full Duplex/Half Duplex operations.
• Provision for Auto-Negotiation of media speed:
10 Mbps or 100Mbps (popularly available for copper media only).
• Maximum Segment Length
• 100 Base TX - 100 m
• 100 Base FX - 2 Km (Multimode Fiber)
• 100 Base FX - 20 km (Singlemode Fiber)

9. Gigabit Ethernet
• 1 Gbps bandwidth.
• Uses same CSMA/CD media access protocol as in
Ethernet and is backward compatible (10/100/100
modules are available).
• 1000BaseT (UTP), 1000BaseSX (Multimode Fiber) and
1000BaseLX (Multimode/Singlemode Fiber) standards.
• Maximum Segment Length
• 1000 Base T - 100m (Cat 5e/6)
• 1000 Base SX - 275 m (Multimode Fiber)
• 1000 Base LX - 512 m (Multimode Fiber)
• 1000 Base LX - 20 Km (Singlemode Fiber)
• 1000 Base LH - 80 Km (Singlemode Fiber

10. 10 Gig Ethernet
• 10 Gbps bandwidth.
• Uses same CSMA/CD media access protocol as in
Ethernet.
• Propositioned for Metro-Ethernet
• Maximum Segment Length
• 1000 Base-T - Not available
• 10GBase-LR - 10 Km (Singlemode Fiber)
• 10GBase-ER - 40 Km (Singlemode Fiber)

11. IEEE 802.5 and Token Ring
• Proposed in 1969 and initially referred to as a Newhall
ring.
• Token ring : a number of stations connected by
transmission links in a ring topology. Information
flows in one direction along the ring from source to
destination and back to source.
• Medium access control is provided by a small frame,
the token, that circulates around the ring when all
stations are idle. Only the station possessing the token
is allowed to transmit at any given time.

12. Token Ring Operation
• When a station wishes to transmit, it must wait for token to pass by
and seize the token.
• One approach: change one bit in token which transforms it into a
“start-of-frame sequence” and appends frame for transmission.
• Second approach: station claims token by removing it from the ring.
• Frame circles the ring and is removed by the transmitting station.
• Each station interrogates passing frame, if destined for station, it
copies the frame into local buffer. {Normally, there is a one bit
delay as the frame passes through a station.}

13. Token Ring Network
with star topology

14. IEEE 802.5 Token Ring
• 4 and 16 Mbps using twisted-pair cabling with differential
Manchester line encoding.
• Maximum number of stations is 250.
• Waits for last byte of frame to arrive before reinserting token on
ring {new token after received}.
• 8 priority levels provided via two 3-bit fields (priority and
reservation) in data and token frames.
• Permits 16-bit and 48-bit addresses (same as 802.3).

15. Token Ring
• Under light load – delay is added due to
waiting for the token.
• Under heavy load – ring is “round-robin”
• The ring must be long enough to hold the
complete token.
• Advantages – fair access
• Disadvantages – ring is single point of failure,
added issues due to token maintenance

16. Networks: Token Ring and FDDI
A
E
DC
B
FDDI Token Ring

17. FIBER DISTRIBUTED DATA
INTERFACE (FDDI)
• PROJECT INITIATED IN OCTOBER 1982 BY JAMES
HAMSTRA AT SPERRY (NOW UNISYS)
• TWO PROPOSALS FOR MEDIA ACCESS CONTROL
(MAC) & PHYSICAL (PHY) LAYERS SUBMITTED IN
JUNE 1983
• FDDI MAC BECAME AN ANSI STANDARD IN LATE
1986
• FDDI PHY WON ANSI STANDARDIZATION IN 1988
• FDDI - II PROPOSAL WAS MADE IN EARLY 1986
• FIRST PUBLIC DEMONSTRATIONS AT ADVANCED
MICRO DEVICES (AMD) IN 1989

18. FDDI BASIC PRINCIPLE
• TOKEN RING NETWORK LIKE IEEE 802.5
• TOKEN: A SPECIAL SEQUENCE OF BITS
• TOKEN CIRCULATES AROUND THE RING
• A STATION REMOVES THE TOKEN FROM RING BEFORE
TRANSMISSION
• AFTER TRANSMISSION, THE STATION RETURNS THE TOKEN TO
THE RING
• COLLISIONS ARE PREVENTED AS THERE IS ONLY ONE TOKEN IN
THE RING

19. FIBER DISTRIBUTED DATA INTERFACE
(FDDI)

20. FDDI ARCHITECTURAL MODEL
• ACCORDING TO THE OSI-RM, FDDI SPECIFIES LAYER 1
(PHYSICAL LAYER) AND PART OF LAYER 2 (DATA LINK
CONTROL LAYER)
• THE PHYSICAL LAYER HANDLES THE TRANSMISSION
OF RAW BITS OVER A COMMUNICATIONS LINK
• THE DATA LINK CONTROL (DLC) LAYER IS
RESPONSIBLE FOR MAINTAINING THE INTEGRITY OF
INFORMATION EXCHANGED BETWEEN TWO POINTS

21. FDDI - II
• SAME FEATURES AS BASIC FDDI (FDDI - I), INCLUDING MAXIMUM
NUMBER OF MODES, 100 MBPS DATA TRANSFER BIT RATE, AND THE
DUAL RING
• DEFINES THE PHYSICAL LAYER AND THE LOWER HALF OF THE DATA LINK
LAYER SIMILAR TO FDDI-I
• FDDI-I SUPPORTS ONLY PACKET MODE (SYNCHRONOUS AND
ASYNCHRONOUS) TRAFFIC, FDDI-II SUPPORTS BOTH PACKET DATA AS
WELL AS ISOCHRONOUS DATA TRAFFIC (IN FDDI ISOCHRONOUS
INDICATES A CLASS OF TRAFFIC FOR VOICE AND VIDEO
• THE SIMULTANEOUS SUPPORT OF BOTH PACKET AND ISOCHRONOUS
TRAFFIC IS CALLED THE HYBRID MODE OF OPERATION

22. A FDDI BACKBONE NETWORK
EXAMPLE

23. FEATURES FDDI ETHERNET TOKEN RING
TRANSMISSION
RATE
125 MBAUD 20 MBAUD 8 & 32 MBAUD
DATA RATE 100 MBPS 10 MBPS 4 & 16 MBPS
SIGNAL
ENCODING
4B/5B (80%
EFFICIENT)
MANCHESTER
(50%
EFFICIENT)
DIFFERENTIAL
MANCHESTER
(50% EFFICIENT)
MAXIMUM
COVERAGE
100 KM 2.5 KM CONFIGURATION
DEPENDENT
MAXIMUM
NODES
500 1024 250
MAXIMUM
DISTANCE
BETWEEN
NODES
2 KM (MULTIMODE
FIBER)
40 KM (SINGLE-
MODE FIBER)
2.5 KM 300 M
(RECOMMENDED
100 M)
COMPARISON WITH OTHER NETWORKS

24. ………. THANK YOU ……….