Chapter 4 : Network access

© 2008 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialPresentation_ID 1
Chapter 4:
Network Access
Introduction to Networks

Presentation_ID 2© 2008 Cisco Systems, Inc. All rights reserved. Cisco Confidential
Chapter 4: Objectives
Upon completion of this chapter, you will be able to:
 Identify device connectivity options.
 Describe the purpose and functions of the physical layer in the
network.
 Describe basic principles of the physical layer standards.
 Identify the basic characteristics of copper cabling.
 Build a UTP cable used in Ethernet networks.
 Describe fiber-optic cabling and its main advantages over other
media.
 Describe wireless media.
 Select the appropriate media for a given requirement and connect
devices.

Chapter 4: Objectives (cont.)
Upon completion of this chapter, you will be able to:
 Describe the purpose and function of the data link layer in
preparing communication for transmission on specific media.
 Describe the Layer 2 frame structure and identify generic fields.
 Identify several sources for the protocols and standards used by
the data link layer.
 Compare the functions of logical topologies and physical
topologies.
 Describe the basic characteristics of media control methods on
WAN topologies.
 Describe the basic characteristics of media control methods on
LAN topologies.
 Describe the characteristics and functions of the data link frame.

4.4 Media Access Control

Chapter 4
4.1 Physical Layer Protocols
4.2 Network Media
4.3 Data Link Layer Protocols
4.4 Media Access Control
4.5 Summary

4.1 Physical Layer Protocols

Getting it Connected
Connecting to the Network

Connecting to the Network (cont.)

Network Interface Cards
Connecting to the Wireless LAN with a Range Extender

Purpose of the Physical Layer
The Physical Layer

Physical Layer Media

Physical Layer Standards
Standard
Organization
Networking Standards
ISO
• ISO 8877: Officially adopted the RJ connectors (e.g., RJ-11, RJ-45)
• ISO 11801: Network cabling standard similar to EIA/TIA 568.
EIA/TIA
• TIA-568-C: Telecommunications cabling standards, used by nearly all
voice, video and data networks.
• TIA-569-B: Commercial Building Standards for Telecommunications
Pathways and Spaces
• TIA-598-C: Fiber optic color coding
• TIA-942: Telecommunications Infrastructure Standard for Data Centers
ANSI • 568-C: RJ-45 pinouts. Co-developed with EIA/TIA
ITU-T • G.992: ADSL
IEEE
• 802.3: Ethernet
• 802.11: Wireless LAN (WLAN) & Mesh (Wi-Fi certification)
• 802.15: Bluetooth

Fundamental Principles of Layer 1
Physical Layer Fundamental Principles
Media
Physical
Components
Frame Encoding
Technique
Signalling Method
Copper
Cable
• UTP
• Coaxial
• Connectors
• NICs
• Ports
• Interfaces
• Manchester Encoding
• Non-Return to Zero (NRZ)
techniques
• 4B/5B codes are used with
Multi-Level Transition Level 3
(MLT-3) signaling
• 8B/10B
• PAM5
• Changes in the
electromagnetic field
• Intensity of the
electromagnetic field
• Phase of the
electromagnetic
wave
Fiber Optic
Cable
• Single-mode Fiber
• Multimode Fiber
• Connectors
• NICs
• Interfaces
• Lasers and LEDs
• Photoreceptors
• Pulses of light
• Wavelength multiplexing using
different colors
• A pulse equals 1.
• No pulse is 0.
Wireless
Media
• Access Points
• NICs
• Radio
• Antennae
• DSSS (direct-sequence
spread-spectrum)
• OFDM (orthogonal frequency
division multiplexing)
• Radio waves

Bandwidth

Throughput

Types of Physical Media
Gigabit Ethernet
Interfaces
SHDSL
Interface
Management
Ports
FastEthernet
Switch Ports
USB Mini-B
Connector
USB Type A
Connector

4.2 Network Media

Copper Cabling
Characteristics of Copper Media

Copper Cabling
Copper Media
Shielded Twisted
Pair (STP) Cable
Unshielded Twisted
Pair (UTP) Cable
Coaxial Cable

Copper Cabling
UTP Cable

Copper Cabling
STP Cable
Foil Shields
Braided or Foil Shield

Copper Cabling
Coaxial Cable

Copper Cabling
Cooper Media Safety

UTP Cabling
Properties of UTP Cabling
UTP cable does not use shielding to counter the effects of EMI and
RFI. Instead, cable designers have discovered that they can limit the
negative effect of crosstalk by:
 Cancellation
 Varying the number of twists per wire pair

UTP Cabling
UTP Cabling Standards

UTP Cabling
UTP Connectors

UTP Cabling
Types of UTP Cable

UTP Cabling
Testing UTP Cables
After installation, a UTP cable tester should be used to test for the following
parameters:
 Wire map
 Cable length
 Signal loss due to attenuation
 Crosstalk

Fiber Optic Cabling
Properties of Fiber Optic Cabling
Fiber-optic cabling is now being used in four types of industry:
 Enterprise Networks
 Fiber-to-the-home (FTTH) and Access Networks
 Long-Haul Networks
 Submarine Networks

Fiber Optic Cabling
Fiber Media Cable Design

Fiber Optic Cabling
Types of Fiber Media

Fiber Optic Cabling
Network Fiber Connectors

Fiber Optic Cabling
Testing Fiber Cables

Fiber Optic Cabling
Fiber versus Copper
Implementation Issues Copper Media Fibre Optic
Bandwidth Supported 10 Mbps – 10 Gbps 10 Mbps – 100 Gbps
Distance
Relatively short
(1 – 100 meters)
Relatively High
(1 – 100,000 meters)
Immunity To EMI And RFI Low
High
(Completely immune)
Immunity To Electrical Hazards Low
High
(Completely immune)
Media And Connector Costs Lowest Highest
Installation Skills Required Lowest Highest
Safety Precautions Lowest Highest

Wireless Media
Properties of Wireless Media
Wireless does have some areas of concern including:
 Coverage area
 Interference
 Security

• IEEE 802.11 standards
• Commonly referred to as Wi-Fi.
• Uses CSMA/CA
• Variations include:
• 802.11a: 54 Mbps, 5 GHz
• 802.11b: 11 Mbps, 2.4 GHz
• 802.11g: 54 Mbps, 2.4 GHz
• 802.11n: 600 Mbps, 2.4 and 5 GHz
• 802.11ac: 1 Gbps, 5 GHz
• 802.11ad: 7 Gbps, 2.4 GHz, 5 GHz, and 60 GHz
• IEEE 802.15 standard
• Supports speeds up to 3 Mb/s
• Provides device pairing over distances from 1 to 100
meters.
• IEEE 802.16 standard
• Provides speeds up to 1 Gbps
• Uses a point-to-multipoint topology to provide
wireless broadband access.
Wireless Media
Types of Wireless Media

Wireless Media
Wireless LAN
Cisco Linksys EA6500 802.11ac Wireless Router

Wireless Media
802.11 Wi-Fi Standards
Standard
Maximum
Speed
Frequency
Backwards
Compatible
802.11a 54 Mbps 5 GHz No
802.11b 11 Mbps 2.4 GHz No
802.11g 54 Mbps 2.4 GHz 802.11b
802.11n 600 Mbps 2.4 GHz or 5 GHz 802.11b/g
802.11ac
1.3 Gbps
(1300 Mbps)
2.4 GHz and 5.5
GHz
802.11b/g/n
802.11ad
7 Gbps
(7000 Mbps)
2.4 GHz, 5 GHz and
60 GHz
802.11b/g/n/ac

4.3 Data Link Layer Protocols

Purpose of the Data Link Layer
The Data Link Layer

Data Link Sublayers
Network
Data Link
LLC Sublayer
MAC Sublayer
Physical
802.3
Ethernet
802.11
Wi-Fi
802.15
Bluetooth

Media Access Control
The Data Link Layer

Providing Access to Media

Data Link Layer
Formatting Data for Transmission

Layer 2 Frame Structure
Creating a Frame

Layer 2 Standards
Data Link Layer Standards
Standard
organization
Networking Standards
IEEE
• 802.2: Logical Link Control (LLC)
• 802.3: Ethernet
• 802.4: Token bus
• 802.5: Token passing
• 802.11: Wireless LAN (WLAN) & Mesh (Wi-Fi certification)
• 802.15: Bluetooth
• 802.16: WiMax
ITU-T
• G.992: ADSL
• G.8100 - G.8199: MPLS over Transport aspects
• Q.921: ISDN
• Q.922: Frame Relay
ISO
• HDLC (High Level Data Link Control)
• ISO 9314: FDDI Media Access Control (MAC)
ANSI • X3T9.5 and X3T12: Fiber Distributed Data Interface (FDDI)

Topologies
Controlling Access to the Media

Topologies
Physical and Logical Topologies

Topologies
Physical and Logical Topologies (cont.)

WAN Topologies
Common Physical WAN Topologies

WAN Topologies
Physical Point-to-Point Topology

WAN Topologies
Logical Point-to-Point Topology

WAN Topologies
Half- and Full-Duplex
Half-Duplex
Full-Duplex

LAN Topologies
Physical LAN Topologies

LAN Topologies
Logical Topology for Shared Media

LAN Topologies
Contention-Based Access
Characteristics Contention-Based Technologies
• Stations can transmit at any time
• Collision exist
• There are mechanisms to resolve
contention for the media
• CSMA/CD for 802.3 Ethernet networks
• CSMA/CA for 802.11 wireless networks

LAN Topologies
Multi-Access Topology

LAN Topologies
Controlled Access
Characteristics Controlled Access Technologies
• Only one station can transmit at a time
• Devices wanting to transmit must wait
their turn
• No collisions
• May use a token passing method
• Token Ring (IEEE 802.5)
• FDDI

LAN Topologies
Ring Topology

Data Link Frame
The Frame

Data Link Frame
The Header

Data Link Frame
Layer 2 Address

Data Link Frame
The Trailer

Data Link Frame
LAN and WAN Frames

Data Link Frame
Ethernet Frame

Data Link Frame
Point-to-Point Protocol Frame

Data Link Frame
802.11 Wireless Frame

Network Access
Summary
 The TCP/IP network access layer is the equivalent of the OSI data link
layer (Layer 2) and the physical layer (Layer 1).
 The OSI physical layer provides the means to transport the bits that make
up a data link layer frame across the network media.
 The physical layer standards address three functional areas: physical
components, frame encoding technique, and signaling method.
 Using the proper media is an important part of network communications.
Without the proper physical connection, either wired or wireless,
communications between any two devices will not occur.
 Wired communication consists of copper media and fiber cable.
 There are three main types of copper media used in networking:
unshielded-twisted pair (UTP), shielded-twisted pair (STP), and coaxial
cable. UTP cabling is the most common copper networking media.

Network Access
Summary (cont.)
 Optical fiber cable has become very popular for interconnecting
infrastructure network devices. It permits the transmission of data over
longer distances and at higher bandwidths (data rates) than any other
networking media.
 Wireless media carry electromagnetic signals that represent the binary
digits of data communications using radio or microwave frequencies.
 The data link layer is responsible for the exchange of frames between
nodes over a physical network media. It allows the upper layers to access
the media and controls how data is placed and received on the media.
 Among the different implementations of the data link layer protocols, there
are different methods of controlling access to the media. These media
access control techniques define if and how the nodes share the media.
 The actual media access control method used depends on the topology
and media sharing. LAN and WAN topologies can be physical or logical.

Network Access
Summary (cont.)
 WANs are commonly interconnected using the point-to-point, hub and
spoke, or mesh physical topologies.
 In shared media LANs, end devices can be interconnected using the star,
bus, ring, or extended star (hybrid) physical topologies.
 All data link layer protocols encapsulate the Layer 3 PDU within the data
field of the frame. However, the structure of the frame and the fields
contained in the header and trailer vary according to the protocol.

Chapter 4 : Network access

More Related Content

What's hot (17)

Similar to Chapter 4 : Network access (20)

More from teknetir (20)

Recently uploaded (20)

Chapter 4 : Network access