• Define common network topologies and identify structured cable distribution schemes
• Identify the major industry bodies and standards, and obtain and read standards documents
• Identify the layers of the Open Systems Interconnection reference model (OSI/RM), and describe the function of each layer
• Relate networking and convergence protocols, services and equipment to each OSI/RM layer
• Explain data encapsulation in relation to frame assembly and function on the network
• Relate common networking and convergence protocols, services and equipment to each of the four layers of the
TCP/IP model
Data Networking

• Network – two or more connected computers that share data
• Host – a computer that participates in a network, often providing services to other computing systems
• Most networks are:
– Local area networks (LANs)
– Wide area networks (WANs)
Data Networking

• The public switched telephone network (PSTN) is an integral part of the Internet infrastructure
• Internet Protocol (IP) telephony – a technology that uses packet-switched connections to exchange voice, fax and other forms of data
• Voice over IP (VoIP) – voice information delivered in digital form as packets of data using IP
• Communications over Internet Protocol (CoIP) – a set of emerging standards defining transmission of multimedia (text, images, video) over the Internet
Data Networking

Network elements:
– Protocols – communication rules on which all network elements must agree
– Transmission media – media (such as cables or wireless technologies) that enable all networking elements to interconnect
– Network services – resources that all network users share
Networking models:
– Mainframe – centralized; all processing is performed by the mainframe
– Client/server – distributed; reduces congestion by dividing processing and storage tasks between the client and the server
– Web-based – increasingly decentralized and more affordable networking
Data Networking

Data Networking

Data Networking

Data Networking

Data Networking

Data Networking

• Backbone cabling – used to connect LANs together
• Campus distributor (CD) – used between routers and switches to connect LANs in different buildings within one general location
• Vertical cabling – considered part of the backbone and runs between floors in a multi-floor building
• Building distributor (BD) – the main interface between public or private telecommunications lines coming into a building and the internal network wiring
• Horizontal wiring – connects individual users to the data or telecommunications network
• Cross-connect – the point at which one type of wiring or cabling is connected with another
Data Networking

(cont'd)
• Wiring closet – a room or closet that houses all equipment associated with telecommunications wiring systems
• Floor distributor (FD) – a rack that interconnects wiring between a BD and workstations
• Patch panel – a group of sockets (usually consisting of pin locations and ports) mounted on a rack
• Punchdown block – a device that connects one group of wires to another group of wires through a system of metal pins to which the wires are attached
Data Networking

• International Organization for Standardization
(ISO)
• International Telecommunications Union (ITU)
• Institute of Electrical and Electronics
Engineers (IEEE)
• Electronic Industries Alliance /
Telecommunications Industry Association (EIA/TIA)
• Communications Information Technology
Association (CITA)
• European Telecommunications Standards
Institute (ETSI)
Data Networking

(cont'd)
• Independent Committee for the Supervision of
Standards of Telephone Information Services
(ICSTIS)
• American National Standards Institute (ANSI)
• Telcordia (formerly Bellcore)
• Internet Society (ISOC)
• Internet Architecture Board (IAB)
• Internet Research Task Force (IRTF)
• Internet Engineering Task Force (IETF)
Data Networking

Layer
Application
Presentation
Session
Transport
Network
Data link
Physical
Layer Number
7
6
5
4
3
2
1
Data Networking

Data Networking

Application-layer protocols
SIP, H.323, MGCP,
SMTP, POP3, HTTP,
DNS, BOOTP, FTP,
Telnet, LDAP
Presentation-layer protocols
ASN.1, Codecs
Session-layer protocols
RTCP, NetBIOS, SQL, ASP
Transport-layer protocols
RTP, TCP, UDP, ATP
Network-layer protocols
IP, ICMP, ARP, DDP
Data link-layer protocols
802.2, 802.3, 802.11
Physical layer
Network hardware or technologies
Data Networking

Data Networking

• Data – the application, presentation and session layers
• Segment – the transport layer
• Packet – the network layer
• Frame – the data link layer
Cyclical redundancy check (CRC) – verifies whether a packet is valid
– Imagine a packet as a package being shipped to you: The CRC would be considered a packing slip or a bill of lading
Data Networking

Packet structure:
– Header
– Data
– Trailer
Data Networking

• Transmission Control Protocol / Internet Protocol
(TCP/IP) – the current de facto standard for both local and wide area networking
• TCP/IP four-layer model:
– Application layer – interacts with the transportlayer protocols to send or receive data
– Transport layer – provides the flow of information between two hosts
– Network/Internet layer – addresses and routes packets on TCP/IP networks
– Link/network access layer – accepts higherlayer packets, creates frames and transmits them over the attached network
Data Networking

Data Networking

 Define common network topologies and identify structured cable distribution schemes
 Identify the major industry bodies and standards, and obtain and read standards documents
 Identify the layers of the Open Systems Interconnection reference model (OSI/RM), and describe the function of each layer
 Relate networking and convergence protocols, services and equipment to each OSI/RM layer
 Explain data encapsulation in relation to frame assembly and function on the network
 Relate common networking and convergence protocols, services and equipment to each of the four layers of the
TCP/IP model
Data Networking

• Compare and contrast the use of E-carrier,
T-carrier, SONET/SDH and ISDN technologies for data and voice networks, including bandwidths of common technologies
• Identify cable terminators
• Define and contrast data communications equipment (DCE) and data terminating equipment (DTE)
• Identify network media, and identify proper cabling procedures in specific environments
• Compare and contrast straight-through, crossover, rolled and null-modem cabling
Data Networking

• Synchronous transmission
– Access device and network device share a clock
• Asynchronous transmission
– No clock in the transmission media
• Data transmission flow
– Simplex – data travels in only one direction
– Half duplex – data travels in two directions, but in only one direction at a time
– Full duplex – data travels in two directions simultaneously
• Baseband and broadband transmissions
– Baseband – uses entire media bandwidth for a single channel
– Broadband – divides the media bandwidth into multiple channels, and each channel carries a separate signal
Data Networking

• Digital signal level zero (DS0) – the basic level of digital communication upon which all other digital signaling levels are built
• Digital Signal Hierarchy (DSH) – an electrical (as opposed to optical) hierarchy used to classify the speed capacities of multiplexed lines
• T-carrier system – a North American high-speed digital carrier system used to transmit data
• E-carrier system – a European high-speed digital carrier system used to transmit data in almost all countries outside the United States, Canada and
Japan
Data Networking

(cont'd)
• Integrated Services Digital Network (ISDN) – a completely digital service capable of carrying voice, fax, imaging or data communications
• Synchronous Optical Network (SONET) – a North
America high-speed fiber-optic system for optical transmissions
• Synchronous Digital Hierarchy (SDH) – an international high-speed fiber-optic system for optical transmissions
Data Networking

Data Networking

Data Networking

ISDN configurations:
– 2B+D – also known as Basic Rate Interface (BRI).
Intended for home use. Uses two 64-Kbps B channels and one 16-Kbps D channel
– 23B+1D – available in the United States and
Japan. Intended for business use. Designed for
23 B channels plus one D channel
– 30B+2D – also known as Primary Rate Interface
(PRI). Available in Europe. Intended for business use. Designed for 30 B channels and two D channels
Data Networking

Data Networking

Data Networking

• It is possible to use multiplexers and routers to combine different data lines and streams onto one line
• One heterogeneous network can communicate with another distant heterogeneous network
Data Networking

• Serial ports
• Universal Serial Bus (USB)
• FireWire (IEEE 1394)
• Parallel ports
• PS/2 connectors
• Small computer system interface (SCSI)
• Amphenol connectors
Data Networking

• Serial ports are computer sockets that connect serial devices to a computer
• Use two types of connectors:
– DB-9 (9-pin) – usually COM1
– DB-25 (25-pin) – usually COM2 and used for modem
Data Networking

• USB interface may replace serial and parallel ports
• USB allows up to 127 devices to be daisy-chained using one USB port
• Two USB standards:
– USB 1.0
offers transfer rate of 12 Mbps for fast devices (and 1.5 Mbps for slow devices)
– USB 2.0
offers transfer rate of up to 480 Mbps
• Two USB connectors:
– Type A is rectangular and relatively small. All permanent connections use the Type A connector
– Type B is square and is only used for devices that use a separate cable
Data Networking

• A serial bus especially popular for attaching video devices to computers
• Allows up to 63 devices to be daisy-chained
• Supports hot swapping
• Guarantees bandwidth for multimedia
• Two FireWire versions:
– IEEE 1394a supports data transfer rates of up to
400 Mbps
– IEEE 1394b supports data transfers of 800 to
1,200 Mbps
Data Networking

• Parallel ports are computer sockets that connect a printer or any other parallel device to a computer
• Enhanced using the IEEE 1284 standard, which provides bi-directional transfers and increased speeds
• Parallel cables can be 32 feet long
Data Networking

• Used to connect a keyboard or a mouse to a computer
• 6-pin circular connector
• Used on all laptops and PCs
Data Networking

• SCSI is a parallel interface that allows two devices to communicate at the same time
• Allows seven to 15 devices to be daisy-chained
• Last device in a daisy chain must have a SCSI terminator
• Three types of SCSI connectors:
– 25-pin (SCSI-1)
– 50-pin (SCSI-2)
– 68-pin (SCSI-3)
Data Networking

Often used in patch cables for connecting 66 and 110 punchdown blocks
Data Networking

Free space transmission media:
– Infrared
– Short-range wireless
– Microwave
– Satellite
Cable transmission media:
– Twisted-pair cable
– Coaxial cable
– Fiber-optic cable
Data Networking

• Infrared (IR) – wireless communication in which signals are sent via light waves that are longer than those of the visible light spectrum
• Short-range wireless – used for networking PCs and for connecting a PC to peripherals
– The most common standard for peripheral device communications is Bluetooth
• Microwave – signals sent by line-of-sight transmission via parabolic antennas mounted on towers
• Satellite – transmits information between two stations that are not within the line of sight of each other
Data Networking

• Maximum segment length of 100 metres
• Available in two basic types:
– Shielded (STP) – twisted copper wrapped in a metal sheath; more difficult to install and maintain than
UTP
– Unshielded (UTP) – most common; less expensive than STP, but prone to electromagnetic interference
• STP and UTP are available in two varieties:
– Stranded – most common; flexible and easy to handle around corners and objects
– Solid – can span longer distances, but less flexible and will break if bent multiple times
Data Networking

Category Description
1
2
3
4
5
5e
6
7
Used for voice only, not data
4 Mbps; used for voice and data
10 Mbps; standard station wire
16 Mbps; used for voice
100 Mbps; Ethernet and Fast Ethernet
Fast Ethernet and Gigabit Ethernet; largely replaces Cat 5
Gigabit Ethernet; more fragile than other categories of twisted pair
1 Gbps; will replace coax cable because it can support cable TV
Data Networking

• Straight-through cable – the transmit wires on one end of the cable connect to the transmit wires on the opposite end of the cable
• Crossover cable – the transmit wires on one end will connect to the receiving wires on the other end, and vice versa
• Rolled cable – a serial cable in which one end of the cable is wired as the mirror image of the other end
• Null-modem cable – an RS-232 serial cable in which the transmit and receive lines are crosslinked
Data Networking

• Used for video and communication networks
• Provides higher bandwidth than twisted-pair cable
• Designed for baseband, broadband and television networks
• Supports data transfer rates from 1 Mbps to
100 Mbps
• Transfer rate of 10 Mbps common for LAN
• Common types: RG-6, RG-11, RG-59
• Uses the F-type connector:
Data Networking

Type Segment Length Use
RG-6 N/A
RG-11 500 m
TV and video; similar to RG-59 but for longer distances
Broadband LAN connections
RG-59 305 m Cable TV, video; often for short distances (e.g., 6 feet)
Data Networking

• Sends data as pulses of light over threads of glass
• Transfer rates in the gigabits-per-second range
• Transmissions can travel for miles without attenuation
• Immune to electromagnetic interference (EMI)
• Two major types:
– Single-mode fiber (SMF) – offers extremely high bandwidth and long distances (up to 70 km)
– Multimode fiber (MMF) – allows for use of inexpensive light sources and used for short distances (less than 200 m); typically specified for LANs and WANs
Data Networking

• ST (straight tip) connector – connects one optical fiber using a one-piece bayonet mounting system; widely implemented in commercial wiring
• SC (subscriber or standard) connector – connects fiber-optic cable using a plug and socket with a push-pull latch
• Fiber LC (local) connector – half the size of a standard ST or SC connector; designed to save space on patch panels
• MT-RJ (mechanical transfer registered jack) – about the same shape and size as an RJ-45, and can be used with single-mode or multimode fiber
Data Networking

• When pulling cable:
– Ensure that you have cleared a proper path
– Avoid sharp bends in the cable
– Take care to eliminate sharp edges in conduits and other areas where cable might get worn or cut
– Make sure that wiring does not interfere with mechanical equipment
– Avoid passing wire close to fluorescent lights
Data Networking

(cont'd)
• The standard jacket of a UTP or STP cable is made of polyvinyl chloride (PVC), which if burned creates toxic polyvinyl chloride gas
• Two options to PVC cabling are available:
– Encase the cable in a protective metal conduit
– Use limited combustible cabling, which has a
Teflon or Kevlar jacket
Data Networking

 Compare and contrast the use of E-carrier,
T-carrier, SONET/SDH and ISDN technologies for data and voice networks, including bandwidths of common technologies
 Identify cable terminators
 Define and contrast data communications equipment (DCE) and data terminating equipment (DTE)
 Identify network media, and identify proper cabling procedures in specific environments
 Compare and contrast straight-through, crossover, rolled and null-modem cabling
Data Networking

• Relate networking and convergence protocols, services and equipment to each OSI/RM layer
• Identify the functions of routers, switches, firewalls, core and edge networks, modems and hubs in relation to data networking hardware
• Explain the format and function of Media Access
Control (MAC) addresses
• Define the Spanning Tree Protocol (STP)
• Define networking methods, standards and protocols, and their characteristics
• Explain the concept of protocol tunneling, and identify elements and benefits of using a Virtual
Private Network (VPN) in a convergent network
Data Networking

(cont'd)
• Identify wireless networking equipment functionality and standards
• Identify and describe common security issues inherent to wireless networks
• Explain the functions of Wired Equivalent Privacy
(WEP), 802.11i/WiFi Protected Access (WPA),
802.1x and Remote Authentication Dial-In User
Service (RADIUS)
• Identify critical settings in an access point (AP)
• Describe wireless client settings, including authentication, encryption, preferred networks, channels
Data Networking

Local area network (LAN):
– A group of computers connected by transmission media within a confined geographic area
– Often consists of workstations and servers
Wide area network (WAN):
– A group of computers connected over an expansive geographic area, such as a state or country
– Often connects two LANs using the communications lines of a public carrier, such as the PSTN
Data Networking

• Network interface card (NIC)
• Repeaters
• Hubs
• Bridges
• Routers
• Switches
• Gateways
• Network termination equipment (NTE)
• Firewalls
• Modems
Data Networking

• Makes the physical connection between the computer and the network cabling
• Operates at the data link layer (Layer 2) of the
OSI/RM
• Requires a device driver
• Every NIC has a MAC address
• Can be attached to a computer by:
– PCI card
– PCMCIA card
– USB
– FireWire
– Wireless
Data Networking

Network Device Interface Specification (NDIS) and
Open Data-Link Interface (ODI):
– Allow a NIC to be chosen independently from the protocols, network operating system (NOS) or applications that will be used
– Enable multiple protocols to be bound to a single NIC
– Enable the use of multiple NICs in the same computer
Note: ODI is similar to NDIS but was defined by Novell and Apple to simplify driver development
Data Networking

• Unique addresses that are burned on a NIC by the manufacturer
• Use 12 hexadecimal digits to form a 48-bit address
• Organisationally Unique Identifier (OUI) – identifies the vendor that created the NIC
• Interface Serial Number – a number unique to the vendor
Data Networking

• Repeat or regenerate the electronic signal from one LAN cable to another, extending the range of the signal
• Operate at the physical layer (Layer 1) of the
OSI/RM
Data Networking

• Connect multiple devices into the same collision domain
• Operate at the physical layer (Layer 1) of the
OSI/RM
Data Networking

• Filter frames to determine whether a specific frame belongs on a local segment or another LAN segment
• Connect networks with the same or different data link protocols
• Operate at the data link layer (Layer 2) of the
OSI/RM
• Independent of all upper-layer protocols
• Largely replaced by switches in modern Ethernet networks because switches are faster
Data Networking

• Forward, or route, data from one network to another
• Operate at the network layer (Layer 3) of the
OSI/RM
• Instead of using MAC addresses, routers use IP or
IPX addresses to forward or route data from one network to another
Data Networking

• Direct the flow of information from one node to another
• Operate at the data link layer (Layer 2) of the
OSI/RM
• Types of switches:
– Layer 1 – connects individual systems
– Layer 2 – forwards traffic based on MAC addresses
– Layer 3 – connects networks
– Layer 4 – forwards traffic between source and destination hosts
Data Networking

• Redundancy in a network eliminates the possibility of single points of failure
• STP identifies one switch from each pair of redundant switches as the designated switch
• STP allows switches to communicate with one another to bypass a failed switch
• STP is defined in the IEEE 802.1d standard
• Rapid Spanning Tree Protocol (RSTP) – an evolved version of 802.1d, which allows for faster spanning-tree convergence after a network topology change
• GARP VLAN Registration Protocol (GVRP) – a protocol that allows for automatic configuration of switches in a
VLAN environment
Data Networking

• Simple installation – Unplug connections from existing devices and plug the connections into the switch ports
• Higher speeds – Switches allow full bandwidth between any two users or segments
• More server bandwidth – Servers can connect directly to switches
• Creation of virtual LANs (VLANs) – VLANs allow you to organise systems according to their logical functions on the network, as opposed to their physical locations
• More default security – Using a VLAN, you can isolate individual systems
Data Networking

• Also called protocol converters
• Can operate from the transport layer (Layer 4) through the application layer (Layer 7) of the
OSI/RM
• Convert one protocol stack into another
• Can be used to connect networks with dissimilar protocols or architectures
Note: Do not confuse a gateway (protocol converter) with a default gateway (router)
Data Networking

• The location where customer data or telephone equipment connects to external lines from the carrier
• Protects the public and private networks from power spikes
• Provides a testing interface
• Converts the carrier's signals into signals for use on the LAN
• Provides timing information
• Performs multiplexing and signaling
Data Networking

• Channel Service Unit / Data (or Digital) Service
Unit
• Terminates physical connections
• Required when using dedicated circuits such as
T1 lines
• Operates at the physical layer (Layer 1) of the
OSI/RM
Data Networking

• A secure computer system placed between a trusted network and an untrusted one, such as the
Internet
• Acts as a barrier against potential malicious activity
• Allows a “door” for people to communicate between a secured network and the open, unsecured network
• A network firewall is most commonly placed between a corporate LAN and the Internet
Data Networking

• Traditionally, a modem is a device that enables computers to communicate over phone lines by translating digital data into audio/analogue signals and then back into digital form
• “Modem” now refers to any device that adapts a computer to a phone line or cable TV network, whether it is digital or analogue
• Analogue modems translate digital data into analogue signals and then back into digital form
• DSL and cable modems are all-digital
Data Networking

• Institute of Electrical and Electronics Engineers
(IEEE) – an organisation of professionals that creates standards for computers and communications
• IEEE 802 network standards:
– IEEE 802.2
– Logical Link Control (LLC) function
– IEEE 802.3
– Ethernet
– IEEE 802.3u
– Fast Ethernet
– IEEE 802.3z
and 802.3ab
– Gigabit Ethernet
– IEEE 802.3ae
(supplement) – 10-Gigabit Ethernet
Data Networking

• X.25
• Fast packet switching
• Frame relay
• Asynchronous transfer mode (ATM)
• Peer-to-peer networking
• Point-to-Point Protocol (PPP)
• Point-to-Point Protocol over Ethernet (PPPoE)
Data Networking

• Defines how connections between user devices and network devices are established and maintained
• Implemented at the network layer (Layer 3) of the
OSI/RM
• Uses two types of virtual circuits:
– Switched virtual circuit (SVC) – a temporary connection used for sporadic data transfers
– Permanent virtual circuit (PVC) – a permanently established connection used for frequent and consistent data transfers
Data Networking

• Tasks such as error correction, packet sequencing and acknowledgments are not performed by the network
• Implemented at the MAC sublayer of the OSI/RM data link layer (Layer 2)
• Technologies include frame relay and asynchronous transfer mode (ATM)
Data Networking

• A packet-switching technology used for WANs and LAN-to-LAN connections that supports data and voice
• Organises data into variable-length packets called frames
PVCs
Corporation
Ports
Data Networking

• A cell-switching or cell-relay technology
• ATM replaces variable-length packets with uniform
53-octet cells
• Primarily a connection-oriented service that supports real-time voice and video, as well as data
• Can transport both connection and connectionless services
• Performs at the data link layer (Layer 2) of the
OSI/RM
Data Networking

• A networking model in which each computer has both client and server capabilities
• P2P is a peer-to-peer network on the Internet
• P2P advantages:
– Cost – Because P2P networks are used on the
Internet, an existing, reliable infrastructure is already in place
– Reliability – Clients use their own network connections, creating a reliable network
– Load distribution – Clients download files from multiple locations, which helps keep any one location from being overburdened
Data Networking

• A communications protocol that allows a computer to connect to the Internet over a phone line
• Used to send and receive IP data packets using a modem
• Enables TCP/IP to run on a Layer 1 link
• Multilink Point-to-Point Protocol (MLPPP) – combines two PPP connections into one, thereby enabling a higher transmission speed
Data Networking

• A communications protocol based on PPP that is used with direct Internet connections
• Enables a point-to-point connection using
Ethernet as the transport
• Used mainly with ADSL services
Data Networking

Term
Connection medium
Remote access server
Perimetre
Topology
Firewall
Description
The physical connection method used in any given network
A dedicated server or collection of servers configured to accept connections
The outer edge of the network, as defined by a firewall
The physical layout of a particular network
A dedicated device that helps create a network perimetre by filtering out packets
Data Networking

Term Description
Virtual Private Network (VPN) The use of encryption to establish a dedicated, encrypted connection between two hosts
Remote Authentication Dial-
In User Service (RADIUS)
IPsec
IEEE 802.1x
A means of centralizing authentication information in dial-up connections
A series of protocols and methods designed to encrypt transmissions between hosts at the network layer
(Layer 3) of the OSI/RM
A method for securing wireless networks by centralizing authentication between multiple wireless access points
Data Networking

• Authentication – the process of determining the identity of a user, a network host or an application process
• Authorization – the act of recognizing an authenticated user, network host or process defined on a particular host or authentication system
Data Networking

• A security technique designed to prevent access to information by converting it into a scrambled
(unreadable) form of text
• Three encryption models:
– Symmetric-key
– Asymmetric-key
– Hash
Data Networking

• One key is used to encrypt and decrypt messages
• All parties must know and trust one another completely, and have confidential copies of the key
• Three most common symmetric algorithms:
– Data Encryption Standard (DES)
– Triple DES
– Advanced Encryption Standard (AES)
Data Networking

• Uses a key pair in the encryption process
• Key pair – a mathematically matched key set in which one key encrypts and the other key decrypts
• One of these keys is made public, whereas the other is kept private
• Two most common asymmetric-key algorithms:
– Rivest, Shamir, Adleman (RSA)
– Digital Signature Algorithm (DSA)
Data Networking

• Uses an algorithm to convert information into a fixed, scrambled bit of code
• Any data that has been run through a hash algorithm cannot be decrypted
• Two most common hash algorithm families:
– Message Digest (MD)
• MD2
• MD4
• MD5
– Secure Hash Algorithm (SHA)
Data Networking

Service
Data confidentiality
Data integrity
Authentication
Non-repudiation
Explanation
Ensures that only the intended recipients of information can view it
Applies digital signatures to ensure that data is not illicitly decrypted
Proves identity
Proves that a transaction has, in fact, occurred
Method
Symmetric-key, asymmetric-key
Hash
Asymmetric-key, in conjunction with hash
Asymmetric-key, hash
Data Networking

• Digital certificates are small files that provide authoritative identification
• A certificate authority (CA) verifies the legitimacy of a digital certificate
• Digital certificates contain digital signatures , which are unique identifiers that authenticate messages
• Digital signatures provide the following services:
– Authentication
– Non-repudiation
– Data integrity
Note: Digital signatures do not provide data confidentiality
Data Networking

• VPN is an encrypted tunnel that provides secure, dedicated access between two hosts across an unsecured network
• Three types of VPNs:
– Workstation-to-server
– Firewall-to-firewall
– Workstation-to-workstation
Data Networking

Tunneling protocol – a protocol that encapsulates data packets into other network packets
Tunneling Component
Passenger protocol
Encapsulation protocol
Transport protocol
Description
The protocol being placed into the encrypted tunnel
Responsible for properly encrypting data to provide confidentiality and integrity
Carries the tunnel packets that contain the passenger protocol(s)
Data Networking

• Used to create VPN connections between a client and a centralized server
• Capable of tunneling and encrypting connections across multiple networks
• PPTP works at the data link layer (Layer 2) of the
OSI/RM
• PPTP supports only IP
Data Networking

• Primarily used to support VPNs over the Internet for non-TCP/IP protocols
• L2TP is an open standard
• L2TP uses enhanced compression techniques
• L2TP supports various network types
• L2TP supports RADIUS and many different protocols
• L2TP does not provide encryption by itself
Data Networking

• An IETF standard that provides packet-level encryption, authentication and integrity between firewalls or between hosts in a LAN
• Contains two elements:
– Authentication Header (AH) – signs the packets to ensure authentication and data integrity
– Encapsulating Security Payload (ESP) – encrypts the data payload
• Two connection modes:
– Tunnel mode – the header and the data packet are encrypted
– Transport mode – only data is encrypted
Data Networking

• Expand connectivity – VPNs allow you to use the
Internet to log on to an internal network
• Save money – Companies can implement VPNs between their remote offices and eliminate the use of expensive private leased lines
• Improve security – VPN transmissions are usually encrypted
• Support telecommuting – Users can securely log on to the corporate network from home
Data Networking

• Man-in-the-middle attacks – Weak VPN connections are vulnerable to attempts to alter messages in transit
• Old access accounts and permissions – VPN servers use their own accounts databases; old accounts may be present, which could allow unauthorised access to the network
• Access from unsecured systems – Remote systems may present a new infection source to the network
• Security dependent on VPN clients – If employees use unsecured connections at their end, network privacy and security can become compromised
Data Networking

• Enable the operation of mobile phones and wireless network connections
• Schemes for allocating channels in a mobile network:
– Frequency Division Multiple Access (FDMA) – divides the frequency band into channels, each of which can carry a voice conversation or data
– Time Division Multiple Access (TDMA) – allows several users to share the same frequency channel
– Code Division Multiple Access (CDMA) – assigns a unique code to each voice call
Data Networking

• A digital cellular phone technology that supports voice and short message service
• Based on TDMA
• Currently the most popular mobile phone system in the world
Data Networking

• Mobile data service used for wireless AP access, short message service, and Internet access
• Three capability classes:
– Class A – device can be connected to GPRS service and GSM service, and can use both at the same time
– Class B – device can be connected to GPRS and GSM service, but can use only one or the other at a given time
– Class C – device is connected to either GPRS or
GSM service
Data Networking

• WiFi (Wireless Fidelity) – generically refers to any type of 802.11 wireless network
• WiFi provides high-speed data connections between mobile devices and WiFi access points using short-range wireless transmissions
• Dual cell phones – phones that can use both a cell network and a WiFi network
Data Networking

Wireless networks use the following types of spread spectrum transmissions:
– Frequency Hopping Spread Spectrum (FHSS) – changes the frequency of a transmission at regular intervals
– Direct Sequence Spread Spectrum (DSSS) – signal is spread over the entire band at once
– Orthogonal Frequency Division Multiplexing
(OFDM) – splits a signal into smaller sub-signals that are transmitted simultaneously on different frequencies
Data Networking

• Ad-hoc – systems use only their NICs to connect with each other
• Infrastructure – systems connect via a centralized wireless access point (AP)
Data Networking

Essential wireless Ethernet elements include:
– Wireless NIC
– Wireless access point (AP)
– Configuration software
– Antenna
– Beacon
– Service Set Identifier (SSID)
Data Networking

• 802.11 (WiFi) – original specification providing for data rates of 1 Mbps or 2 Mbps in the 2.4-GHz band using either FHSS or
DSSS
• 802.11a
– operates at 54 Mbps in the 5-GHz band; uses
OFDM
• 802.11b
– operates at 11 Mbps in the 2.4-GHz band; uses
DSSS
• 802.11e
– provides Quality of Service (QoS) standards for wireless networks
• 802.11g
– operates at up to 54 Mbps in the 2.4-GHz band; uses OFDM or DSSS
• 802.11h
– solves problems with wireless networks operating in the 5-GHz band from interfering with satellites and radar
• 802.11i
– specifies wireless security enhancements
Data Networking

Common security problems with wireless networks include:
– Cleartext transmissions
– Access control
– Unauthorised APs and wireless systems
– Corporate users participating in ad hoc networks
– Weak and/or flawed encryption
– Encryption and network traffic
– War driving
Data Networking

• Wired Equivalent Privacy (WEP) – encrypts all data packets sent between wireless clients and the AP
• MAC address filtering – limits access to your network by configuring the AP to allow only certain system MAC addresses to communicate with the rest of the network
• WiFi Protected Access (WPA) – a specification of security enhancements for WiFi networks
• IEEE 802.1x
– authenticates users who want to access 802.11x wireless networks
• Remote Authentication Dial-In User Service
(RADIUS) – a popular method for centralizing remote user access
Data Networking

Access point settings:
– SSID
– Channel
– Broadcast of SSID frames
– Authentication mode – either open or shared key
– Keys for shared key access, if shared key authentication is to be used
– Encryption level – 40-bit, 64-bit, 128-bit or
256-bit
Data Networking

(cont'd)
Wireless client settings:
– The networks to which you want to connect
– The channel used by each network
– The authentication mode (whether open or shared key) used by the access point
– Security settings, which include a shared key (if shared-key authentication is used) and the encryption level
Data Networking

• A wireless access point also has an RJ-45 plug that allows you to attach it to a standard, wired
Ethernet network
• All wireless clients will then be able to access all of the services available to standard Ethernet clients
Data Networking

 Relate networking and convergence protocols, services and equipment to each OSI/RM layer
 Identify the functions of routers, switches, firewalls, core and edge networks, modems and hubs in relation to data networking hardware
 Explain the format and function of Media Access
Control (MAC) addresses
 Define the Spanning Tree Protocol (STP)
 Define networking methods, standards and protocols, and their characteristics
 Explain the concept of protocol tunneling, and identify elements and benefits of using a Virtual
Private Network (VPN) in a convergent network
Data Networking

(cont'd)
 Identify wireless networking equipment functionality and standards
 Identify and describe common security issues inherent to wireless networks
 Explain the functions of Wired Equivalent Privacy
(WEP), 802.11i/WiFi Protected Access (WPA),
802.1x and Remote Authentication Dial-In User
Service (RADIUS)
 Identify critical settings in an access point (AP)
 Describe wireless client settings, including authentication, encryption, preferred networks, channels
Data Networking

• Identify common ports and services
• Define common internal and external routing protocols, and distinguish between internal and external routing protocol functions
• Explain dynamic, static and default routes, and describe the function of routing tables
• Compare and contrast connection-oriented and connectionless transport
• Define and identify well-known, registered and random/dynamic ports
• Compare and contrast the IPv4 and IPv6 address formats
• Determine the network address/number when given a host address and subnet mask
• Identify network, host and broadcast addresses
• Define unicasting, broadcasting, multicasting and anycasting
Data Networking

(cont'd)
• Explain private network addressing
• Identify the importance of the subnet mask
• Identify the subnet mask by bit count and by dotted decimal notation, and define Classless Interdomain Routing
(CIDR)
• Determine the number of host addresses in a subnet
• Describe the impact of proxies on convergent network communications
• Explain Network Address Translation (NAT)
• Identify Domain Name System (DNS) features and functions
• Explain functions and benefits of automatic addressing including protocol steps, and troubleshooting handsets, PCs and all IP-enabled devices
• Determine which Internet Protocol (IP) version to implement
(e.g., IPv4 vs. IPv6)
Data Networking

• Transmission Control Protocol / Internet Protocol
(TCP/IP) – allows computers from different vendors with various operating systems and capabilities to communicate
• Internet Protocol (IP) address – The numerical address assigned to a specific computer that uniquely identifies and distinguishes a node from any other node on the Internet
Data Networking

Data Networking

• Routing – the process of selecting a path over which to send packets in a network
• Router – a device that routes data packets between networks based on network-layer addresses
• The network layer (Layer 3) performs the routing function
• Two general classifications:
– Direct routing
– Indirect routing
Data Networking

• Direct routing – when two computers on the same physical network need to communicate, the packets do not require a router
• Indirect routing – When two computers that are not on the same physical network need to communicate, they must send the IP packet to a router for delivery because they are located on remote networks
Data Networking

Routing involves the following two key elements:
– The host must know which router to use for a given destination; the router is determined by the default gateway
– The router must know where to send the packet; the destination is determined by the router's routing information table
Data Networking

• Routing information table – a database maintained by a router
• Contains the location of all networks in relation to the router's location
Data Networking

• Static router – contains a routing information table that must be built and updated manually by a system administrator
• Dynamic router – communicates with other dynamic routers to calculate routes automatically using routing protocols such as RIP and OSPF
• Default route – the network route used by a router when no other known route exists for a given destination IP address
Data Networking

• Internal routing protocols – used within an organisation’s network
– Routing Information Protocol (RIP)
– Open Shortest Path First (OSPF)
• External routing protocols – used outside an organisation’s network
– Exterior Gateway Protocol (EGP)
– Border Gateway Protocol (BGP)
Data Networking

• Distance-vector routing protocol – designed to allow a router to inform neighbouring routers about the contents of its routing table
• Four common distance-vector routing protocols:
– Routing Information Protocol 2 (RIPv2)
– Interior Gateway Routing Protocol (IGRP)
– Enhanced Interior Gateway Routing Protocol
(EIGRP)
– Exterior Gateway Protocol (EGP)
Data Networking

• Link-state routing protocol – gathers network statistics to create a network map so that routing tables can be altered accordingly
• Two common link-state routing protocols:
– Open Shortest Path First (OSPF)
– Border Gateway Protocol v4 (BGPv4)
Data Networking

• Internet Group Management Protocol (IGMP) – used on routers that support multicast groups
• Multicast – a transmission that is sent to a group of network hosts via a single IP address
• IP hosts use IGMP to register their membership in a multicast group
Data Networking

• Data fragmentation – if a packet is too large for any of the routers encountered along the way, the oversized packets will be fragmented
• Maximum transmission unit (MTU) – the maximum size of a packet or frame on the network; most networks impose a limit on bytes of data per packet
Data Networking

• Connection-oriented protocols – gain a system's attention, prepare it to receive information, then send the information
– An example of a connection-oriented protocol is Transmission Control Protocol (TCP)
• Connectionless protocols – rely on a “best-effort” technology that sends the information, hoping that it will reach the other system
– An example of a connectionless protocol is
Internet Protocol (IP)
Data Networking

Port Number
Range
0 to 1023
1024 to 49151
49152 to 65535
Description Uses
Well-known
(reserved) port numbers
Registered port numbers
Dynamic port numbers
Used by TCP and UDP to identify well-known services that a host can provide
Any process or user can open this range of ports
Any client-side application can open these ports randomly when accessing remote hosts
Data Networking

• Internet addresses are specified by four fields, separated by periods: field1.field2.field3.field4
• Each field represents one byte of data, and has a value ranging from 0 to 255
• In a dotted quad IP address, the first set of numbers on the left represents the largest network; the last number in the address (on the far right) identifies the specific computer
Data Networking

• To determine the value of an Internet address, you must convert from decimal to binary
Bit
Value
128 64 32 16 8 4 2 1
• If the binary value of an IP address is 01111001, you can determine the decimal value by adding the corresponding bit values that equal 1
01111001 = 0 + 64 + 32 +16 +8 +0 +0 +1 =121
Data Networking

• The hexadecimal numbering system uses the digits
0 through 9, and the letters A through F
• A=10; B=11; C=12; D=13; E=14; F=15
Data Networking

Class A: Range 0.0.0.0 to 127.255.255.255
Starting
Binary
Value
0 Network (1 byte)
126 Networks
Host (3 bytes)
16,777,214 Hosts
Class B: Range 128.0.0.0 to 191.255.255.255
Starting
Binary
Value
1 0 Network (2 bytes)
16,384 Networks
Class C: Range 192.0.0.0 to 223.255.255.255
Starting
Binary
Value
1 1 0 Network (3 bytes)
2,097,152 Networks
Class D: Range 224.0.0.0 to 239.255.255.255
Starting
Binary
Value
1 1 1 0
Host (2 bytes)
65,534 Hosts
Multicasting—network (4 bytes)
Host (1 byte)
254 Hosts
Class E: Range 240.0.0.0 to 247.255.255.255
Starting
Binary
Value
1 1 1 1 0 Experimental/reserved for future use
Data Networking

(cont'd)
• Class A – range 0.0.0.0 to 127.255.255.255
• Class B – range 128.0.0.0 to 191.255.255.255
• Class C – range 192.0.0.0 to 223.255.255.255
• Class D – range 224 to 239 (network address only)
• Class E – range 240 to 247 (network address only – reserved for future use)
Data Networking

• Loopback address
– 127 address range
• Broadcast address
– 255
• Network address
– If the host portion of an IP address is all zeros, then that address is a network address
• Special-case source address
– 0.0.0.0 – used for requesting an IP address from a
DHCP or BOOTP server
• Multicasting
– Allows a device to send to a group of devices through one IP address
Data Networking

• Private network addresses are not
Internet-addressable
Class
Class A
Class B
Class C
Private IP Address Range
10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255
Subnet Mask
255.0.0.0
255.240.0.0
255.255.0.0
Data Networking

• Subnetworks offer a way to organise hosts within a network into logical groups
• Subnet masks:
– Distinguish the network and host portions of an
IP address
– Specify whether a destination address is local or remote
• ANDing is a function that a computer uses with its local IP address and local subnet mask in order to determine whether a destination address is local or remote
Data Networking

• Step 1: Determine the number of subnets needed
• Step 2: Determine the number of bits to borrow from the host portion
• Step 3: Determine the subnet mask
• Step 4: Determine the maximum number of hosts per subnetwork
• Step 5: Determine the subnetwork addresses for each subnet
• Step 6: Determine the address ranges for each subnetwork
Data Networking

• Classless Interdomain Routing (CIDR) – a method used to minimize the number of routing table entries
• The basic concept in CIDR is to allocate multiple IP addresses so they can be summarized into a smaller number of routing table entries
• This strategy relieves routers of additional workload
Data Networking

• Proxy servers:
– Replace the network IP address with another, contingent address.
– Allow a network to be represented by one IP address on the Internet
• Network Address Translation (NAT):
– The process of translating one IP address into another
– NAT allows system administrators to use any IP addressing scheme internally, and one or more registered IP addresses externally
Data Networking

Types of NAT:
– Port Address Translation (PAT) – multiple IP addresses are translated into one valid IP address
– Static address translation – multiple IP addresses are mapped to valid IP addresses in a one-toone relationship
– Dynamic address translation – multiple IP addresses are mapped to valid IP addresses randomly
Data Networking

Basic configurations:
– IP address
– Subnet mask
– Default gateway
– DHCP client
– DNS server
Data Networking

(cont'd)
Additional TCP/IP services:
Service
Domain Name System (DNS) service
Windows Internet Naming Service
(WINS)
Automatic Private IP Addressing
(APIPA)
Description
Resolves names to IP addresses
A Windows system name resolution service that runs automatically and does not require configuration
Used if a modern Windows client fails to obtain an address from a DHCP server
Data Networking

(cont'd)
Name resolution configurations:
– Host name
– Domain name
– DNS server
– NetBIOS name
– WINS server
Data Networking

• DNS translates IP addresses into easily recognizable names
• Domain name syntax:
Data Networking

• Root-level domain – contains entries for each top-level domain
• Top-level domain – consists of categories found at the end of domain names (such as .com or .uk)
• Second-level domain – include the businesses and institutions that register their domain names with the top-level domains
.(root) ie se com xyz user1 ftp mx net ch iso user2 www
Data Networking

DNS consists of two key components:
– Name server – a server that supports name-to-address translation and runs the DNS service
– Name resolver – software that uses the services of one or more name servers to resolve unknown requests
Data Networking

• DNS follows the standard client/server model:
The client makes a request, and the server attempts to fulfill that request
• Server types included in the DNS model:
– Root server
– Primary server
– Secondary server
– Caching-only server
– Forwarding server
Data Networking

DNS Record
Name Server (NS)
Mail Exchanger (MX)
Service (SRV)
Naming Authority Pointer
(NAPTR)
Function
Identifies DNS servers for the DNS domain
Start Of Authority (SOA) Identifies the DNS server that is the best source of information for the DNS domain
Associates a host to a 32-bit IPv4 address Address (A)
Address (AAAA) Associates a host name to a 128-bit IPv6 address
Canonical Name (CNAME) Creates an alias for a specified host
Pointer (PTR) Maps an IPv4 address to the canonical name for that host
Identifies a server used to process and deliver email messages for the domain
Allows you to specify a server for a particular address
Used to store rules used by Dynamic Delegation
Discovery System (DDDS) applications
Data Networking

• A TCP/IP application-layer protocol that enables diskless workstations to determine IP addresses and parametres
• BOOTP can return information such as IP addresses, subnet masks, default gateway addresses and name server addresses
• BOOTP is a client/server program
Data Networking

• A protocol that assigns IP addresses automatically on a TCP/IP network
• Along with an IP address, DHCP can specify:
– Subnet mask
– Default gateway
– DNS server
– WINS server
• IP addresses can be reserved by mapping an IP address in the DHCP pool to a client’s MAC address
Data Networking

• IPv4 vs. IPv6 addresses
– Different length
• IPv4 – 32 bits divided into four 8-bit integers
• IPv6 – 128 bits divided into eight 16-bit integers
– Different notation
• IPv4 – dotted decimal
• IPv6 – colon notation
– Different number system
• IPv4 – decimal
• IPv6 – hexadecimal
Data Networking

IPv6 supports three types of addresses:
– Unicast – a point-to-point address that is assigned to a single entity
– Multicast – a single IP address assigned to a group; multicasting is a one-to-many communication
– Anycast – similar to multicast; when communicating to an anycast address, the closest member of the anycast group is found, and the message is sent only to that member of the group
Data Networking

 Identify common ports and services
 Define common internal and external routing protocols, and distinguish between internal and external routing protocol functions
 Explain dynamic, static and default routes, and describe the function of routing tables
 Compare and contrast connection-oriented and connectionless transport
 Define and identify well-known, registered and random/dynamic ports
 Compare and contrast the IPv4 and IPv6 address formats
 Determine the network address/number when given a host address and subnet mask
 Identify network, host and broadcast addresses
 Define unicasting, broadcasting, multicasting and anycasting
Data Networking

(cont'd)
 Explain private network addressing
 Identify the importance of the subnet mask
 Identify the subnet mask by bit count and by dotted decimal notation, and define Classless Interdomain Routing
(CIDR)
 Determine the number of host addresses in a subnet
 Describe the impact of proxies on convergent network communications
 Explain Network Address Translation (NAT)
 Identify Domain Name System (DNS) features and functions
 Explain functions and benefits of automatic addressing including protocol steps, and troubleshooting handsets, PCs and all IP-enabled devices
 Determine which Internet Protocol (IP) version to implement
(e.g., IPv4 vs. IPv6)
Data Networking

• Describe the need for Quality of Service (QoS) in converged networks, including identifying problems that occur without
QoS
• Summarize the importance of QoS to real-time solutions
• Compare and contrast QoS with Class of Service (CoS)
• Compare and contrast best-effort delivery and QoS with traffic shaping
• Identify QoS technologies, describe network neutrality issues, and identify proprietary and open-source solutions
• Describe the Type of Service (TOS) field in an IP packet
• Explain the roles of 802.1p, 802.1q and 802.1d when providing QoS, including implementation of traffic shaping using VLANs or protocols
Data Networking

(cont'd)
• Describe QoS on wireless networks (802.11e), including
Wireless Multimedia Extensions (WME) / WiFi Multimedia
(WMM)
• Describe fundamental VLAN functions, features and concepts
• Identify benefits of using a VLAN
• Identify typical problems that occur without a VLAN
• List common troubleshooting steps
• Use the Internet Control Message Protocol (ICMP) to determine connectivity
• Identify common configuration errors in IP devices
• Explain the effects of Network Address Translation (NAT) and
Port Address Translation (PAT) on convergence solutions such as Session Initiation Protocol (SIP), including workarounds and solutions
Data Networking

• Quality of Service (QoS) – a defined system for measuring and improving end-to-end performance in communications networks
• Three levels of QoS:
– Best-effort service – provides no guarantees of delivery, speed or order of delivery
– Differentiated service (Class of Service) – marks some traffic to indicate that it should be treated with priority over the rest of the traffic
– Guaranteed service – confirms an absolute reservation of network resources for specific traffic
Data Networking

• Class of Service (CoS) – A set of QoS technologies and software mechanisms that determine packet priority in IP networks on a hop-by-hop basis
• Three basic CoS technologies:
– 802.1p Layer 2 tagging
– IP Precedence (use of the Type of Service [TOS] field in an IP packet header)
– Differentiated Services (DiffServ)
Data Networking

• Traffic shaping – the process of controlling the volume and rate of traffic sent in to a network
• Traffic-shaping mechanisms include:
– Buffers – incoming traffic is buffered to help with flow control
– Queues – outgoing traffic is separated into distinct data flows and then directed to the appropriate queues on a forwarding device
– Traffic-shaping algorithms – control the amount of data injected into the network
Data Networking

Problems encountered in best-effort delivery networks:
– Delay – packets are held up in a queue or arrive later because they took different routes
– Jitter – quality problems caused by different delays
– Dropped packets – packets may be dropped when a router's buffer is full
– Corrupted packets – packets may be corrupted during transmission
– Disordered packet delivery – packets may arrive out of sequence
Data Networking

QoS standards and protocols:
– Differentiated Services (DiffServ)
– Integrated Services (IntServ)
– Multiprotocol Label Switching (MPLS)
– 802.1p and 802.1q
Data Networking

• DiffServ – differentiates data packets into classes to ensure preferential treatment for higher-priority traffic
• Type of Service (TOS) field – stipulates the level of service that the data requires
• TOS elements:
– Precedence bits
– Delay bit
– Throughput bit
– Reliability bit
– Cost bit
– Bit 7
Data Networking

Using the three Precedence bits of the TOS field (0, 1 and 2), a network administrator could assign priority levels from 0 (default) to 7
(highest) to classify and prioritize types of traffic at Layer 3, as shown:
Priority Level Precedence Bits Traffic Type
6
7
4
5
2
3
0
1
100
101
110
111
000
001
010
011
Routine
Priority
Immediate
Flash
Flash Override
Critical
Internetwork Control
Network Control
Data Networking

• IntServ – an architecture that uses RSVP to reserve the total bandwidth along the entire network path before data transmission takes place
• Resource Reservation Protocol (RSVP) – an IETF standard that allows an application to request the
QoS it needs by sending end-to-end control messages along the data's path
• IntServ and RSVP operate by reserving capacity in the network, based on the needs of a session, before the session is set up
Data Networking

• MPLS – a QoS technology that allows routers and switches to instantly recognise a packet and pass it along a set of predetermined paths
– MPLS integrates Layer 2 information about network links into Layer 3 within a particular system
• Label Edge Router (LER) – a 32-bit header added to a packet when the packet enters an MPLS network
– The MPLS LERs enable the MPLS network to route once and switch thereafter
• The major advantage to MPLS is speed
Data Networking

• IEEE 802.1p
– prioritizes network traffic at the MAC sublayer of the OSI data link layer (Layer 2)
• IEEE 802.1q
– defines the creation of VLAN tags, which are used by the 802.1p standard to prioritize network traffic
• IEEE 802.1d
(Spanning Tree Protocol [STP]):
– Builds a loop-free network when redundant paths are present
– Activates standby links when a primary path becomes unavailable
Data Networking

• On wireless LANS based on the 802.11 standard:
– All users share the network bandwidth
– No one packet gets priority over any other
• 802.11 uses two coordination functions:
– Distributed Coordination Function (DCF)
– Point Coordination Function (PCF)
• Neither DCF nor PCF differentiate between traffic types or sources
Data Networking

• IEEE 802.11e
– defines QoS mechanisms for wireless networks
• Enhances DCF and PCF through the Hybrid
Coordination Function (HCF) , which has two methods of channel access:
– Enhanced DCF Channel Access (EDCA) – highpriority traffic has a higher chance of being sent than low-priority traffic
– HCF Controlled Channel Access (HCCA) – enables applications such as VoIP and streaming video to function more effectively on
WiFi networks
Data Networking

• WMM – prioritizes wireless network traffic and provides basic QoS services
• A subset of the 802.11e standard
• Categorizes and prioritizes traffic
• Does not provide guaranteed throughput
• Four access categories:
– Voice (highest priority)
– Video
– Best effort
– Background (lowest priority)
• Also known as Wireless Multimedia Extensions
(WME)
Data Networking

Virtual local area networks (VLANs):
– Are a group of nodes in the same broadcast domain
– Are created with software instead of hardware
– Are implemented on switches
– Eliminate collision domains
– Operate on the data link layer (Layer 2) of the
OSI/RM
– Function without depending on the physical topology of the LAN
Data Networking

• 802.1q
– defines the process by which frames can be tagged as belonging to a specific VLAN
• Standard Ethernet frame:
• 802.1q frame:
Data Networking

Includes the following three components:
– A 3-bit user_priority field
– A 1-bit canonical format identifier (CFI)
– A 12-bit VLAN ID field (VID)
Data Networking

Includes a 3-bit priority field that allows frames to be grouped into eight traffic classes:
5
6
3
4
7
2
0
Priority Level
1
Traffic Type
Background
Undefined
Best Effort
Examples
The lowest priority
Undefined
Typical network traffic
Excellent Load
Controlled Load
Video
Voice
Business-critical
Streaming multimedia
Video-conferencing
IP telephony
Network Control Reserved Network-management traffic
Data Networking

• Port group-based VLANs – membership based on manual configuration of ports on a switch
• MAC-based VLANs – membership based on MAC address of device connected to a given switch port
• Layer 3-based VLANs – membership based on
Layer 3 information (protocol type or network layer address)
• Authentication-based VLANs – membership based on authentication credentials of user or device using 802.1x protocol
Data Networking

• Benefits of VLANs:
– Vital to the successful function of time-sensitive applications
– The ability to prioritize and smooth traffic allows network devices to perform load balancing
– Makes network management a little easier
– Allows for protocol management on the network
• Convergence without VLANs:
– Convergence applications may not get the bandwidth and network access they require
– Time-sensitive applications suffer from extended delays, causing jitter
Data Networking

Successful troubleshooting steps can be categorized into four areas:
– Analyzing the scope of the problem
– Applying troubleshooting methods
– Using troubleshooting indicators
– Using troubleshooting tools
Data Networking

• Knowing a problem's scope helps you determine its severity
• Consider the following questions:
– How many machines or network segments are affected?
– How frequently does the problem occur?
– Can the problem be duplicated?
Data Networking

Use the DETECT acronym to remember appropriate troubleshooting methods:
• D – Discover the problem
• E – Evaluate the scope of the problem
• T – Track approaches to solving the problem
• E – Execute an approach
• C – Check for problem resolution
• T – Transfer knowledge
Data Networking

Network operating systems include error-logging and reporting utilities:
– Windows systems – Application log, Security log and System log
– Windows Event Viewer utility
– Linux operating systems log errors in the
/var/log/messages file
– Mac OS X and BSD systems log errors in the
/var/system.log file
– Indicator lights – point out reliable connections, errors and activity
Data Networking

Common troubleshooting tools include:
– Crossover cables – can eliminate hubs and switches as potential causes of connectivity problems
– Hardware loopback devices – can determine whether the device can communicate with itself, indicating that the TCP stack is functioning correctly on the device
– Tone generators and tone locators (fox and hound) – can identify network cabling
Data Networking

• Every administrator of a TCP/IP network should be familiar with the following two network files:
– The services file – contains port numbers for well-known services
– The protocol(s) file – identifies the Internet protocols used on a network
Data Networking

• ICMP – a protocol that relays messages when a host is unavailable
• Known as the troubleshooting protocol of TCP/IP
• A required part of the TCP/IP stack
• Allows Internet hosts and gateways to report errors:
– Source-quench error messages – generated when packets arrive too quickly for a host or gateway to process
– Echo-request and echo-reply query messages – used by the ping command to test reachability results
Data Networking

Use the following commands to assist with general network troubleshooting:
– ping
– tracert / traceroute
– netstat
– telnet
Data Networking

• Tests connectivity between source and destination systems
• Syntax: ping ip_address
• Includes several options:
Data Networking

Data Networking

• Used to determine the path between the source and destination systems
• Provides information on round-trip propagation time between each router and the source system
• You can use tracert to locate failures far from your local network
Note: UNIX uses traceroute
Data Networking

Data Networking

• Displays information about packets processed by your system on the network
• Shows the state of sockets
• If executed without specifying options, the netstat command displays established active connections:
Data Networking

• Allows users to log on to a remote computer, provided that permission has been granted
• Ideal for troubleshooting because you can log on to a system from wherever you are and work as if you were sitting in front of it
Data Networking

The following commands are helpful when troubleshooting name resolution problems:
– ipconfig / ifconfig
– arp
Data Networking

• The ipconfig command is used to display IP configurations in Windows
• Syntax: ipconfig options
• Options include:
– /all – shows all IP-related configuration information
– /release – releases IP addresses obtained from a
DHCP server
– /renew – renews IP addresses obtained from a
DHCP server
• The ifconfig command is used to display IP configuration settings in UNIX-based systems, including
Linux; has much of the same functionality as the
Windows ipconfig command
Data Networking

Data Networking

• Displays and modifies the Internet-to-MAC-address translation tables used by the Address Resolution
Protocol (ARP)
• ARP resolves software (IP) addresses into hardware
(MAC) addresses
Data Networking

• Used for:
– Monitoring network traffic to identify network trends
– Identifying network problems and sending alert messages
– Identifying specific problems
– Testing network connections, devices and cables
• Also known as protocol analyzers
Data Networking

• DNS name resolution
– Is the address for the DNS server correct?
• Hosts file configuration
– Is the lmhosts file accurate?
• Static vs. dynamic IP addressing
– Are two nodes attempting to use the same IP address?
• Default gateway and subnet mask
– Is the default gateway specified correctly?
– Is the proper subnet mask specified?
Data Networking

• Firmware updates – can provide additional features and functionality for various types of devices
• Proxy settings – you must configure both the server and your IP devices to work together
• Communication mode – When an IP device operates in half-duplex, other devices will fall back to half-duplex when communicating with that device
Data Networking

• NAT and PAT can pose problems for VoIP communications that use SIP
• If you need to implement SIP in a network where
NAT and PAT are used, consider the following workarounds:
– Simple Traversal of UDP through Network
Address Translators (STUN)
– Traversal Using Relay NAT (TURN)
– Universal Plug and Play (UPnP)
– Application Layer Gateway (ALG)
Data Networking

 Describe the need for Quality of Service (QoS) in converged networks, including identifying problems that occur without
QoS
 Summarize the importance of QoS to real-time solutions
 Compare and contrast QoS with Class of Service (CoS)
 Compare and contrast best-effort delivery and QoS with traffic shaping
 Identify QoS technologies, describe network neutrality issues, and identify proprietary and open-source solutions
 Describe the Type of Service (TOS) field in an IP packet
 Explain the roles of 802.1p, 802.1q and 802.1d when providing QoS, including implementation of traffic shaping using VLANs or protocols
Data Networking

(cont'd)
 Describe QoS on wireless networks (802.11e), including
Wireless Multimedia Extensions (WME) / WiFi Multimedia
(WMM)
 Describe fundamental VLAN functions, features and concepts
 Identify benefits of using a VLAN
 Identify typical problems that occur without a VLAN
 List common troubleshooting steps
 Use the Internet Control Message Protocol (ICMP) to determine connectivity
 Identify common configuration errors in IP devices
 Explain the effects of Network Address Translation (NAT) and
Port Address Translation (PAT) on convergence solutions such as Session Initiation Protocol (SIP), including workarounds and solutions
Data Networking

 Introduction to Data Networking
 Transmission, Communication and Wiring
 LANs and WANs
 TCP/IP Suite and Internet Addressing
 QoS, VLANs and Troubleshooting
Data Networking