Post on 13-Jan-2016
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 Control Protocol/Internet Protocol (TCP/IP)– Suite of small,
specialized protocols called subprotocols
OSI Model TCP/IP
FIGURE 3-1 TCP/IP compared to the OSI Model
TCP/IP Compared to theOSI 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
FIGURE 3-2 Components of an IP datagram
TCP
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
TransportUDP,, TCP
Application
InternetIP , ICMP
Network Interface
ARP
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/IP-based 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
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
TABLE 3-1 Commonly used TCP/IP classes (4 exist)
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