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Chapter Three
Network
Protocols
Agenda
Attendance, and Ch.2 Quiz questions TCP/IP Model IP Header (Using Ethereal to analyze
the IP header) TCP Header (using Ethereal to
analyze the TCP Header) Address Resolution Protocol Lab
Introduction to Protocols
Protocol Rules 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
TCP/IP model File Transfer Protocol (FTP) Hypertext Transfer Protocol (HTTP) Simple Mail Transfer Protocol (SMTP) Domain Name System (DNS) Trivial File Transfer Protocol (TFTP)
The common transport layer
protocols include: Transport Control Protocol (TCP) User Datagram Protocol (UDP)
The primary protocol of the
Internet layer is: Internet Protocol (IP)
TCP/IP model
TCP/IP Compared to theOSI Model
Application layer roughly corresponds to Session, Application, and Presentation layers of OSI Model
Transport layer roughly corresponds to Transport and session layers of OSI Model
Internet layer is equivalent to Network layer of OSI Model
Network Interface layer roughly corresponds to Data Link and Physical layers of OSI Model
The TCP/IP Core Protocols
Certain subprotocols of TCP/IP suite Operate in Transport or Network layers of
OSI Model Provide basic services to protocols in
other layers of TCP/IP TCP and IP are most significant core
protocols in TCP/IP suite
Internet Protocol (IP) Provides information about how and where
data should be delivered Subprotocol that enables TCP/IP to
internetwork To internetwork is to traverse more than one
LAN segment and more than one type of network through a router
In an internetwork, the individual networks that are joined together are called subnetworks
Internet Protocol (IP)
IP datagram IP portion of TCP/IP frame that acts as an envelope for data Contains information necessary for routers to transfer data
between subnets
IP header format
IP header format: Version
• 4 bits.• Indicates the version of
IP currently used.– IPv4 : 0100– IPv6 : 0110
• 4 bits.• Indicates the version of
IP currently used.– IPv4 : 0100– IPv6 : 0110
IP header format: Header length
• 4 bits.• IP header length : Indicates the
datagram header length in 32 bit words (4 bits), and thus points to the beginning of the data.
• 4 bits.• IP header length : Indicates the
datagram header length in 32 bit words (4 bits), and thus points to the beginning of the data.
IP header format: Service type
• 8 bits.• Specifies the level of importance
that has been assigned by a particular upper-layer protocol.• Precedence. • Reliability. • Speed.
• 8 bits.• Specifies the level of importance
that has been assigned by a particular upper-layer protocol.• Precedence. • Reliability. • Speed.
IP header format: Total length
• 16 bits.• Specifies the length of the
entire IP packet, including data and header, in bytes.
• 16 bits.• Specifies the length of the
entire IP packet, including data and header, in bytes.
IP header format: Identification
• 16 bits.• Identification contains an integer
that identifies the current datagram.• Assigned by the sender to aid in
assembling the fragments of a datagram.
• 16 bits.• Identification contains an integer
that identifies the current datagram.• Assigned by the sender to aid in
assembling the fragments of a datagram.
IP header format: Flags
• 3 bits.• The second bit specifying whether the
packet can be fragmented .• The last bit specifying whether the packet
is the last fragment in a series of fragmented packets.
• 3 bits.• The second bit specifying whether the
packet can be fragmented .• The last bit specifying whether the packet
is the last fragment in a series of fragmented packets.
IP header format: Fragment offset
• 13 bits.• The field that is used to help piece together
datagram fragments.• The fragment offset is measured in units of
8 octets (64 bits). • The first fragment has offset zero.
• 13 bits.• The field that is used to help piece together
datagram fragments.• The fragment offset is measured in units of
8 octets (64 bits). • The first fragment has offset zero.
IP header format: Time to Live
• 8 bits.• Time-to-Live maintains a counter that
gradually decreases to zero, at which point the datagram is discarded, keeping the packets from looping endlessly.
• 8 bits.• Time-to-Live maintains a counter that
gradually decreases to zero, at which point the datagram is discarded, keeping the packets from looping endlessly.
IP header format: Protocol
• 8 bits.• Indicates which upper-layer protocol receives
incoming packets after IP processing has been completed• 06 : TCP• 17 : UDP
• 8 bits.• Indicates which upper-layer protocol receives
incoming packets after IP processing has been completed• 06 : TCP• 17 : UDP
IP header format: Header checksum
• 16 bits.• A checksum on the header only,
helps ensure IP header integrity.
• 16 bits.• A checksum on the header only,
helps ensure IP header integrity.
IP header format: Addresses
• 32 bits each.• Source IP Address• Destination IP Address
• 32 bits each.• Source IP Address• Destination IP Address
IP header format: Options
• Variable length.• Allows IP to support various options,
such as security, route, error report ...
• Variable length.• Allows IP to support various options,
such as security, route, error report ...
IP header format: Padding
• The header padding is used to ensure that the internet header ends on a 32 bit boundary.
• The header padding is used to ensure that the internet header ends on a 32 bit boundary.
Ethereal Lab (Analyzing the IP Header)
Use Ethereal to capture some frames. Open one of the frames and look at the IP header. Based on what you see, try to answer the following:
What is the IP version? What is the IP header length? What is the type of Service? What is the time to live? What is the protocol? What is the source IP address? What is the destination IP address?
Internet Protocol (IP)
IP is an unreliable, connectionless protocol, which means it does not guarantee delivery of data Connectionless
Allows protocol to service a request without requesting verified session and without guaranteeing delivery of data
Transport Control Protocol (TCP)
TCP Provides reliable data delivery services Connection-oriented subprotocol
Requires establishment of connection between communicating nodes before protocol will transmit data
TCP segment Holds TCP data fields Becomes encapsulated by IP datagram
Transport Control Protocol (TCP) Port
Address on host where application makes itself available to incoming data
Ethereal Lab (Analyzing the TCP Header)
Use Ethereal to capture some frames. Open one of the frames and look at the TCP header. Based on what you see, try to answer the following:
What is the source Port? What is the destination Port? What is the sequence Number? What Is the Acknowledgement Number? What is the header Length?
Additional Core Protocols of the TCP/IP Suite User Datagram Protocol (UDP)
Connectionless transport service Internet Control Message Protocol (ICMP)
Notifies sender of an error in transmission process and that packets were not delivered
Address Resolution Protocol (ARP) Obtains MAC address of host or node Creates local database mapping MAC address to
host’s IP address
ARP Lab
Agenda
Attendance and questions about last week’s material.
TCP/IP Application Layers FTP Lab Telnet Lab
Break Binary and hexadecimal conversion
TCP/IP Application Layer Protocols
Telnet Used to log on to remote hosts using TCP/IP protocol
suite
File Transfer Protocol (FTP) Used to send and receive files via TCP/IP
Simple Mail Transfer Protocol (SMTP) 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
Labs
FTP Lab Telnet Lab
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) that are separated by periods
IP addresses are assigned and used according to very specific parameters
Addressing in TCP/IP
Though 8 bits have 256 possible combinations, only the numbers 1 through 254 are used to identify networks and hosts
Number 255 is reserved for broadcasts Broadcast are 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 Internet Corporation for Assigned Names and
Numbers (ICANN) Non-profit organization currently designated by
U.S. government to maintain and assign IP addresses
Addressing in TCP/IP
Firewall Specialized device (typically a router) 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 2000, 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 equivalent of 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 (DHCP) Application layer protocol Manages dynamic distribution of IP
addresses on a network
Viewing Current IP Information
Viewing Current IP Information
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 Together, host name and domain name
constitute the fully qualified domain name (FQDN)
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 NetBEUI
NetBIOS and NetBEUI
NetBIOS Enhanced User Interface Fast and efficient protocol Consumes few network resources Provides excellent error correction Requires little configuration Can handle only 254 connections Does not allow for good security
NetBIOS Addressing
Installing Protocols
After installing protocols, they must be binded to NICs and services they run on or with Binding
Process of assigning one network component to work with another
Chapter Summary Protocols define standards for
communication between nodes on a network
Protocols vary in speed, transmission efficiency, utilization of resources, ease of setup, compatibility, and ability to travel between one LAN segments
TCP/IP is the most popular network protocol
Chapter Summary TCP/IP suite of protocols can be divided into
four layers roughly corresponding to seven layers of OSI Model
Operating in Transport or Network layers of OSI Model, TCP/IP core protocols provide communications between hosts on a network
Each IP address is a unique 32-bit number, divided into four groups of octets separated by periods
Chapter Summary Every host on a network must have a unique
number Internetworking Packet Exchange/Sequenced
Packet Exchange (IPX/SPX) is a protocol originally developed by Xerox then modified and adopted by Novell in the 1980s for its NetWare network operating system
Core protocols of IPX/SPX provide services at Transport and Network layers of OSI Model
Chapter Summary Addresses on an IPX/SPX network are called
IPX addresses Network Basic Input Output System
(NetBIOS) was originally developed by IBM to provide Transport and Session layer services
Microsoft adopted NetBIOS as its foundation protocol, then added an Application layer component called NetBIOS Enhanced User Interface (NetBEUI)
Chapter Summary To transmit data between network nodes,
NetBIOS needs to know how to reach each workstation Each workstation must have a NetBIOS name
AppleTalk is the the protocol suite used to interconnect Macintosh computers
An AppleTalk network is separated into logical groups of computers called AppleTalk zones
Chapter Summary Though Apple has improved AppleTalk’s ability
to use different network models and span network segments, it remains unsuited to large LANs or WANs
In addition to zone names, AppleTalk uses node IDs and network numbers to identify computers on a network
Though some protocols (such as NetBIOS) require no configuration after installation, others (such as TCP/IP) do require configuration
Next Week
Make sure that you have taken chapter 3 Quiz online
Make sure that you have read chapter 11 Download packet tracer from my web site
and install it at home. Try to read the tutorial to gain some understanding on how it works. You will use this program in your project