Chapter Overview

1
Chapter Overview

• Ethernet
• Token Ring
• FDDI
• Wireless Networking

2
Ethernet Standards

• Ethernet is the most popular local area network
  (LAN) protocol operating at the data-link layer.
• There are two sets of Ethernet standards
• DIX Ethernet
• Institute of Electrical and Electronic Engineers
  (IEEE) 802.3

3
DIX Ethernet Standards

• DIX Ethernet. Also known as thick Ethernet,
  ThickNet, or 10Base5
• DIX Ethernet II. Retains 10Base5 and adds 10Base2
  (thin Ethernet)

4
IEEE 802.3 Standards

• IEEE 802.3. 10Base5, 10Base2, and 10Base-T
• IEEE 802.3u. Fast Ethernet
• IEEE 802.3z and IEEE 802.3ab. Gigabit Ethernet

5
DIX Ethernet/IEEE 802.3 Components

• Physical layer specifications
• Frame format
• CSMA/CD MAC mechanism

6
Standard 10-Mbps Ethernet Specifications
Designation Cable Type Topology Maximum Length
10Base5 RG-8 coaxial Bus 500 meters
10Base2 RG-58 coaxial Bus 185 meters
10Base-T Category 3 UTP Star 100 meters
Fiber Optic Inter-Repeater Link (FOIRL) Multimode fiber optic Star 1,000 meters
10Base-F Multimode fiber optic Star 5002,000 meters
7
Fast Ethernet (100 Mbps) Specifications
Designation Cable Type Topology Maximum Length
100Base-TX Category 5 UTP Star 100 meters
100Base-T4 Category 3 UTP Star 100 meters
100Base-FX Multimode fiber optic Star 412 meters

8
Gigabit Ethernet (1,000 Mbps) Specifications
Designation Cable Type Topology Maximum Length
1000Base-T Category 5 or 5E UTP Star 100 meters
1000Base-LX Various multimode fiber optic Star 5505,000 meters
1000Base-SX Various multimode fiber optic Star 220500 meters
1000Base-LH Singlemode fiber optic Star 10 kilometers
1000Base-ZX Singlemode fiber optic Star 100 kilometers
1000Base-CX 150-ohm copper Star 25 meters
9
Coaxial Ethernet Standards

• 10Base5 (thick Ethernet)
• 10Base2 (thin Ethernet)

10
Coaxial Network Characteristics

• Runs at 10 Mbps
• Uses the bus topology
• Uses mixing segments

11
Mixing Segments
12
UTP Ethernet Standards

• 10Base-T
• 100Base-TX (Fast Ethernet)
• 100Base-T4 (Fast Ethernet)
• 1000Base-T (Gigabit Ethernet)

13
UTP Network Characteristics

• Runs at various speeds up to 1,000 Mbps
• Uses the star topology
• Requires a hub
• Uses link segments

14
Link Segments
15
Fiber Optic Ethernet

• Fiber Optic Inter-Repeater Link (FOIRL)
• IEEE 802.3 fiber optic standards
• 10Base-FL
• 10Base-FB
• 10Base-FP
• 100Base-FX
• Gigabit Ethernet standards

16
The 5-4-3 Rule

• A standard network can have no more than FIVE
  segments, connected by FOUR repeaters, of which
  no more than THREE segments can be mixing
  segments.

17
A Coaxial 5-4-3 Network
18
A UTP 5-4-3 Network
19
Fast Ethernet Hub Types
Class Function
I Connects different cable segment types
II Connects identical cable segment types
20
Fast Ethernet Cabling Guidelines
Hub Type Maximum Number of Hubs Maximum Total Cable Length (UTP) Maximum Total Cable Length (Fiber Optic)
Class I 1 200 meters 272 meters
Class II 2 205 meters 228 meters
21
The Ethernet Frame Format
22
Protocol Identification

• DIX Ethernet frames use the Ethertype field.
• IEEE 802.3 frames use the Logical Link Control
  (LLC) and Subnetwork Access Protocol (SNAP)
  subheaders.

23
Media Access Control (MAC)

• Is the mechanism that enables multiple computers
  to use the same network medium without
  conflicting

24
CSMA/CD Phases
Phase Description
Carrier sense A computer listens to the network before transmitting.
Multiple access When the network is clear, the computer transmits the packet.
Collision detection The computer checks for signs of a collision. If one occurs, it retransmits the packet.
25
Collisions

• Collisions are also called signal quality errors.
• They are normal on Ethernet networks.
• The frequency of collisions increases as network
  traffic increases.
• Late collisions are a sign of a serious problem.

26
Token Ring Cable Types

• IBM Type 1. Proprietary shielded twisted pair
  (STP) (Up to 300 meters 260 Workstations)
• IBM Type 3. Standard Category 5 unshielded
  twisted pair (UTP) (Up to 150 meters 72
  Workstations)

27
IBM Type 1 Cable
Lobe Cable
28
Token Passing

• A token frame circulates continuously around the
  network.
• Only the computer holding the token can transmit
  data.
• The transmitting system is responsible for
  removing the data from the ring.

29
Token Ring Frame Types

• Data frame
• Token frame
• Command frame
• Abort delimiter frame

30
The Data Frame Format (Operates at the LLC)
31
The Token Frame Format
32
Fiber Distributed Data Interface (FDDI)
Characteristics

• First commercial 100-Mbps fiber optic protocol
• Uses the token passing MAC mechanism
• Supports both
• singlemode cable (600 Km segments)
• multimode cable (100 Km segments 500
  Workstations)

33
FDDI Topologies

• Double ring (Wrap Ring)
• Logical ring
• Dual ring of trees

34
Dual Ring of Trees
35
FDDI (Fiber Distributed Data Interface) Frame
Types

• Data frame
• Token frame
• Station Management Frame (In charge of the ring
  maintenance and Network diagnostics)

36
The FDDI Data Frame
37
Wireless NetworkingIEEE 802.11 Standards

• IEEE 802.11a. Speeds of 1 to 2 Mbps
• IEEE 802.11b. Speeds of 5.5 to 11 Mbps

38
IEEE 802.11 Topologies

• Ad hoc (or Independent). Wireless computers
  communicating with each other
• Infrastructure. Wireless computers using an
  access point to communicate with a cabled network

39
IEEE 802.11 Signals Supported

• Direct Sequence Spread Spectrum (DSSS)
• Frequency Hopping Spread Spectrum (FHSS)
• Infrared

40
CSMA/CA

• Carrier Sense Multiple Access with Collision
  Avoidance (CSMA/CA) is a variation of CSMA/CD.
• It uses packet acknowledgment messages instead of
  collision detection.

41
Chapter Summary

• Ethernet
• Supports multiple cable types and speeds
• Uses the CSMA/CD MAC mechanism to detect
  collisions
• Token Ring
• Uses a logical ring topology
• Uses the token passing MAC mechanism
• FDDI
• Uses a double ring or star topology
• Uses the token passing MAC mechanism
• Wireless Networking
• Runs at speeds up to 11 Mbps
• Uses the CSMA/CA MAC mechanism