lesson 24. protocols and the osi model. objectives at the end of this presentation, you will be able...
TRANSCRIPT
Lesson 24. Protocols and the OSI Model
Objectives
At the end of this Presentation, you will be able to:
• Define protocol and explain why different protocols are required.
• Identify the main protocols that make up the TCP/IP Suite including TCP, IP, UDP, POP3, SMTP, IMAP4, SNMP, FTP, TFTP, NTP, and HTTP.
• Explain the purpose of each of the above protocols.
Network+ Domains covered:
• 2.2• 2.4• 2.10
In Networking, Protocols are:
• Agreements that describe how things work. • Industry-wide frameworks that describe
every aspect of communications between computers.
• Grouped together into Protocol Suites.
In the PC world, the main Protocol Suites are:
• NetBEUI – Used in small Microsoft-based networks.
• IPX/SPX – Used primarily in Novell-based networks.
• TCP/IP – Must be used if the network is to connect to the Internet. But it is also widely used even in those networks that do not connect to the Internet.
OSI Model vs. TCP/IP Stack
Application
Presentation
Session
Transport
Network
Data Link
Physical1
2
3
4
5
6
7
IP
TCP UDP
SMTP FTP SNMP
SMB RFS NFS
HTTP
Protocols of the TCP/IP Suite: • TCP• IP• UDP• POP3/IMAP4• SMTP• SNMP• FTP• TFTP• HTTP• NTP
Protocols of the TCP/IP Suite: • TCP• IP• UDP• POP3/IMAP4• SMTP• SNMP• FTP• TFTP• HTTP• NTP
Delivery Service
Transmission Control Protocol (TCP)
• Connection-oriented, reliable delivery service.
• Demands that a connection be established before communications can begin.
• Views data as a stream that is broken into segments and assigned sequence numbers.
Connection-Oriented Protocol
Setup Request
Setup ResponseSending
HostReceiving
Host
Network
Connection-Oriented Protocol
Data Sequence
Acknowledgement
SendingHost
ReceivingHost
Network
6 5 1234
Connection-Oriented Protocol
Connection Clear
Clear Response
Host Host
Network
Setup Request
Setup Response
Data Sequence
Acknowledgement
Connection Clear
Clear Response
Session
Application
Presentation
Session
Transport
Network
Data Link
Physical1
2
3
4
5
6
7
Transmission Control Protocol (TCP)
Internet Protocol (IP)
• Another type of delivery service.• Not connection-oriented, not guaranteed reliable.• Data viewed as a packet.• No acknowledgement that packet was received.• Provides routing information from the sender to
the receiver.
Application
Presentation
Session
Transport
Network
Data Link
Physical1
2
3
4
5
6
7
Internet Protocol (IP)
TCP vs. IP
• Connection-oriented• Reliable Delivery• Transport Layer Protocol• High overhead
• Connectionless• “Best-effort” Delivery• Network Layer Protocol• Low overhead
The IPX/SPX Suite has protocols that are comparable
to TCP and IP.• SPX is roughly equivalent to TCP• IPX is roughly equivalent to IP
Sequenced Packet Exchange (SPX)
• Connection-Oriented• Reliable delivery• Views data as a sequence of packets
(Stream)• Operates at the Transport Layer of the OSI
model.
Internetwork Packet Exchange (IPX)
• Connectionless• Reliable delivery cannot be guaranteed• Operates at the Network Layer of the OSI
model.
Application
Presentation
Session
Transport
Network
Data Link
Physical
IP
TCP
IPX
SPX
OSI Model
TCP/IPStack
IPX/SPXStack
User Datagram Protocol (UDP)
• Another delivery service.• Has some of the features of both TCP and IP.• Like TCP, it breaks data into a sequence of packets
and numbers them. • Operates at the Transport layer of the OSI Model. • Connectionless service, no guarantee of delivery.
Protocols of the TCP/IP Suite: • TCP• IP• UDP• POP3/IMAP4• SMTP• SNMP• FTP• TFTP• HTTP• NTP
Post Office Protocol (POP)
• Widely used e-mail access protocol.• Used to download e-mail from an e-mail server to
an e-mail client.• Version 3 or POP3 is the current version of the
software.• Used to receive e-mail, but not to send it.• Uses TCP as its transport protocol, therefore
delivery is reliable.
Post Office Protocol (POP)
• Works best from a single computer.• Messages are downloaded and then deleted
from the mail server. • Not compatible with access from multiple
computers. • Messages are scattered across all of the
computers used for mail access.
Internet Message Access Protocol Version 4 (IMAP4)
• Used to access electronic mail or bulletin board messages from a mail server.
• Ability to access messages from more than one computer.
Simple Mail Transfer Protocol (SMTP)
• Used to send e-mail.• Used for PC to e-mail server
communications.• Used for e-mail server to e-mail server
communications.• Uses TCP as a transport protocol, so it is
reliable.
Protocols of the TCP/IP Suite:
• TCP• IP• UDP• POP3/IMAP4• SMTP• SNMP• FTP• TFTP• HTTP• NTP
Network Management
File Transfer
HyperText TransferTime Synchronization
Simple Network Management Protocol
• Used to communicate network status information.
• Used to indicate the health of the network to network management consoles.
• Originally used to monitor bridges and routers.
• Extended to include servers, hubs, and mainframe computers.
File Transfer protocol (FTP)
• Both a protocol and a program.• Allows fast, secure, and error-free file
transfer between two hosts.• Uses TCP as its Transport Protocol.• Because it is a TCP/IP protocol, it is NOS-
independent.
Trivial File Transfer Protocol (TFTP)
• Can be thought of as a “lite” version of FTP. Similar to FTP except that …
• It uses UDP as its transport protocol.• It does not have any type of authentication
and therefore is considered less secure.
Hypertext Transfer Protocol (HTTP)
• Used to transfer Web pages from a Web Server to a Web Browser.
• The Uniform Resource Locator (URL) in the Address line of your Browser is often prefixed by HTTP as in: HTTP//WWW.HEATHKIT.COM
Network Time Protocol (NTP)
• Widely used on the Internet to synchronize computer clocks to a standard time.
• A synchronization protocol that can read a server’s clock, transmit the reading to various clients, and adjust each client’s clock accordingly.
• Define protocol and explain why different protocols are required.
• Identify the main protocols that make up the TCP/IP Suite including TCP, IP, UDP, POP3, SMTP, IMAP4, SNMP, FTP, TFTP, NTP, and HTTP.
• Explain the purpose of each of the above protocols.