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Addressing Through the Layers
 Data Link Layer Address
 Network Layer Address
Data Link Layer Address
 Also called MAC address, after Media
Access Control (MAC) sublayer
 Number uniquely defining a network node
 Manufacturer-hard codes the address
– Block ID
– Device ID
Network Layer Address
 Resides at Network level of OSI Model
 Follows hierarchical addressing scheme
 Can be assigned through operating system
software
 Why would we use BOTH a Network address
AND a MAC address?
Data Link Layer Sublayers
 LLC
– Upper sublayer
– Provides common interface
– Supplies reliability and flow control services
 MAC
– Lower sublayer
– Appends the physical address of the destination
computer onto the frame
 IEEE Ethernet and Token Ring differ here
Chapter Three
Network
Protocols
Chapter Objectives
 Identify the characteristics of TCP/IP,
IPX/SPX, NetBIOS, and AppleTalk
 Understand the position of network protocols
in the OSI Model
 Identify the core protocols of each protocol
suite and its functions
 Understand each protocol’s addressing scheme
 Install protocols on Windows 95 and Windows
NT clients
Introduction to Protocols
 Protocols
– Rules a network uses to transfer data
– Protocols that can span more than one LAN
segment are routable
 Multiprotocol Network
– Network using more than one protocol
TCP/IP
 Transmission
OSI Model
TCP/IP
Control
Protocol/Internet
Protocol
(TCP/IP)
– Suite of small,
specialized
protocols called
subprotocols
FIGURE 3-1 TCP/IP compared
to the OSI Model
TCP/IP Compared to the
OSI Model
 Application layer roughly corresponds to
Application and Presentation layers
 Transport layer roughly corresponds to Session
and Transport layers
 Internet layer is equivalent to the Network layer
 Network Interface layer roughly corresponds to
Data Link and Physical layers
Internet Protocol (IP)
 Provides information about how and where data
should be delivered
 Subprotocol enabling TCP/IP to internetwork
– Traverse more than one LAN segment and more than
one type of network through a router
– Subnets
• The individual networks joined together by routers in an
internetwork
Internet Protocol (IP)
 IP Datagram
– IP portion of a
TCP/IP frame
that acts as an
envelope for
data
– Contains
information
necessary for
routers to
transfer data
between
subnets
TCP
FIGURE 3-2 Components of an IP datagram
Internet Protocol (IP)
 What is a Datagram?
– Packaged data sent without establishment of a
communication channel or connection
 IP does not guarantee delivery of data
– Connectionless
• Allows the protocol to service a request without
requesting a verified session and without
guaranteeing delivery of data
Transport Control Protocol (TCP)
 Provides reliable data delivery services
 Connection oriented
– Requires the establishment of a connection
between communicating nodes before the protocol
will transmit data
 TCP segment
– Holds the TCP data fields
– Becomes encapsulated by the IP datagram
Transport Control Protocol (TCP)
 Port
– Address on host where an application makes itself
available to incoming data
FIGURE 3-3
A TCP
segment
header
TCP/IP Protocols
Telnet, FTP, SMTP, SNMP
Application
UDP,, TCP
Transport
IP , ICMP
Internet
ARP
Network
Interface
Additional Core Protocols of the
TCP/IP Suite
 User Datagram Protocol (UDP)
– A connectionless transport service
– Less overhead than TCP
 Internet Control Message Protocol (ICMP)
– Notifies the sender that something has gone
wrong in the transmission process and that
packets were not delivered
– No error control
– PING uses this
Additional Core Protocols of the
TCP/IP Suite
 Address Resolution Protocol (ARP)
– Obtains the MAC address of a host or node
– Creates a local database mapping the MAC
address to the host’s IP address
– Used in conjunction with IP
TCP/IP Application Layer
Protocols
 Telnet is used to log on to remote hosts using TCP/IP
Protocol
 File Transfer Protocol (FTP) is used to send and
receive files via TCP/IP
 Simple Mail Transfer Protocol (SMTP) is
responsible for moving messages from one e-mail
server to another, using the Internet and other TCP/IPbased networks
 Simple Network Management Protocol (SNMP)
manages devices on a TCP/IP network
Addressing in TCP/IP
 IP Address
– Logical address used in TCP/IP networking
– Unique 32-bit number
• Divided into four groups of octets (8-bit bytes)
• Separated by periods
Addressing in TCP/IP
TABLE 3-1 Commonly used TCP/IP classes (4 exist)
 How did we get the # of hosts? - 28 , 216 , 224
 Though 8 bits have 256 possible combinations,
only the numbers 1 through 254 are used to
identify networks and hosts
 Numbers 0 and 255 are reserved for broadcasts
– Transmissions to all stations on a network
Addressing in TCP/IP
 Loopback address
– IP address reserved for communicating from a node
to itself
– Value of the loopback address is always 127.0.0.1
 InterNIC
– Authority for Internet IP addressing and domain
name registration
– Also known as Network Solutions
Addressing in TCP/IP
 Firewall
– Specialized device
– Selectively filters or blocks traffic between
networks
– May be strictly hardware-based or may involve a
combination of hardware and software
 Host
– Computer connected to a network using the TCP/IP
protocol
Addressing in TCP/IP
 In IP address 131.127.3.22, to convert the first
octet (131) to a binary number:
– On Windows 95, click Start, point to Programs,
point to Accessories, then click Calculator
– Click View, then click Scientific (make sure Dec
option button is selected)
– Type 131, then click Bin option button
– The binary number 131, 10000011, appears in the
display window
Addressing in TCP/IP
 Static IP address
– IP address manually assigned to a device
 Dynamic Host Configuration Protocol protocol
– Application layer protocol
– Manages the distribution of IP addresses on a
network
Viewing IP Information
 On a Windows 95
workstation connected
to a network
– Click Start, then click
Run
– Type winipcfg
• (ipconfig /all (NT at
DOS prompt)
– Click OK
– Click More Info
– Click OK to close
window
FIGURE 3-4 Example of an IP configuration window
Addresses and Names
 In addition to using IP addresses, TCP/IP
networks use names for networks and hosts
– Each host requires a host name
– Each network requires a network name, also
called a domain name
• Symbolic name that identifies and Internet domain
IPX/SPX
 Internetwork Packet
Exchange/Sequenced
Packet Exchange
(IPX/SPX)
– Protocol originally
developed by Xerox
– Modified and adopted
by Novell in the
1980s for the
NetWare network
operating system
 NWLink - Microsoft
IPX/SPX emulation
FIGURE 3-6 IPX/SPX compared to the
OSI Model
IPX/SPX Core Protocols
 IPX
– Network layer
– Connectionless routing
 Sequence Packet Exchange (SPX)
– Works in tandem with IPX to ensure data are
received (and acknowledged):
• Whole
• In sequence
• Error free
IPX/SPX Core Protocols
 Service Advertising Protocol (SAP)
– Runs directly over IPX
– Used by NetWare servers and routers to advertise
to entire network which services they can provide
 NetWare Core Protocol (NCP)
– Handles requests for services between clients and
servers
 Read for yourself
NetBIOS and NetBEUI
 Network Basic Input Output System
(NetBIOS)
– Originally designed by IBM to provide Transport
and Session layer services
– Adopted by Microsoft as its foundation protocol
– Microsoft added Application layer component
called NetBIOS Enhanced User Interface
(NetBEUI)
NetBEUI
 Fast and efficient protocol
 Consumes few network resources
 Provides excellent error correction
 Requires little configuration
 254 connection limit removed for later
versions
 Non routable
AppleTalk
 Protocol suite used to interconnect Macintosh
computers
 Originally designed to support peer-to-peer
networking among Macintoshes
 Can now be routed between network segments and
integrated with NetWare- and Microsoft-based
networks
Installing Protocols
 After installing protocols, they must be binded
 Binding
– Process of assigning one network component to
work with another