Layer 4 of the TCP/IP protocol stack: Application
level
Services: TELNET, FTP, SMTP, HTTP, DNS, RIP, NFS
Hierarchy of protocols and services
Contents
1. Overview of the TCP/IP Networking Model
2. Comparison between OSI and TCP/IP
Networking Models
3. Layer 4 (Application Layer) Overview
4. TCP Services
5. Conclusion
6. Sources
Overview of the TCP/IP Networking
Model
• Created in 1970s by DARPA
• Describes the guidelines for creation of
specific protocols to enable communication
over network
• Divided into layers
Comparison between OSI and TCP/IP
Networking Models
• The OSI Model
- Layer 1 – Physical
- Layer 2 – Data Link
- Layer 3 – Network
- Layer 4 – Transport
- Layer 5 – Session
- Layer 6 – Presentation
- Layer 7 – Application
Comparison between OSI and TCP/IP
Networking Models
• The TCP/IP Model
– Layer 1 – Link
– Layer 2 – Network
– Layer 3 – Transport
– Layer 4 - Application
Comparison between OSI and TCP/IP
Networking Models
Layer 4 (Application Layer) Overview
• Refers to the higher-level protocols used by
most applications for network communication
• Application layer protocols are most often
associated with client-server applications, and
the commoner servers have specific ports
assigned to them
TCP/IP Services
• TELNET
- Primary goal - to allow a standard method of interfacing terminal devices and
terminal-oriented processes to each other
TCP/IP Services
• FTP
- Primary goal - to allow the exchange and manipulate files over a TCP/IP based
network, such as the Internet
TCP/IP Services
• Types of FTP - From a networking perspective, the
two main types of FTP:
- active
- passive
In active FTP, the FTP server initiates a data transfer
connection back to the client. For passive FTP, the
connection is initiated from the FTP client.
TCP/IP Services
TCP/IP Services
• SMTP
- Primary goal – SMTP is a a text-based protocol, in which a
mail sender communicates with a mail receiver over a reliable
ordered data stream channel, typically a Transmission Control
Protocol (TCP) connection
TCP/IP Services
TCP/IP Services
• HTTP
- Primary Goal - HTTP is an application-level protocol for distributed, collaborative,
hypermedia information systems. Its use for retrieving inter-linked resources,
called hypertext documents, led to the establishment of the World Wide Web
- Resources to be accessed by HTTP are identified using Uniform Resource Identifiers
(URIs)—or, more specifically, Uniform Resource Locators (URLs)—using the http or
https URI schemes.
TCP/IP Services
TCP/IP Services
• DNS
- Primary Goal – The DNS is a hierarchical naming system for computers, services, or
any resource connected to the Internet or a private network. It associates various
information with domain names assigned to each of the participants.
TCP/IP Services
TCP/IP Services
• RIP
- Primary Goal - (RIP) is a dynamic routing protocol used in local and wide area
networks. As such it is classified as an interior gateway protocol (IGP). It uses the
distance-vector routing algorithm.
TCP/IP Services
• NFS
- Primary Goal - Network File System (NFS) is a network file system protocol
originally developed by Sun Microsystems in 1984, allowing a user on a client
computer to access files over a network in a manner similar to how local storage is
accessed.
Conclusion
In the last few years the IT has reached a new phase. Servers and home workstations
being able to transfer terabytes of data daily, multicore systems, multimedia
systems are all around us. In this satiation to understand the basics of the TCP/IP
Networking Model is a must for every system administrator nowadays. In this
paper we have covered some of the main aspects of the model such as:
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Overview of the TCP/IP Networking Model
Comparison between OSI and TCP/IP Networking Models
Layer 4 (Application Layer) Overview
Various TCP Services (TELNET, FTP, SMTP, HTTP, DNS, RIP, NFS) as long as their
implementation and impact in our everyday live as users and as system
administrators.
Sources
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http://en.wikipedia.org/wiki/Internet_Protocol_Suite
http://www.speedguide.net/read_articles.php?id=120
http://www.ietf.org/rfc/rfc854.txt
http://www.faqs.org/rfcs/rfc959.html
http://elqui.dcsc.utfsm.cl/util/redes/TCPIP%20Tutorial%20and%20Technical%20
Overview/3376c44.html
http://codeidol.com/unix/linux-fix/Linux-FTP-Server-Setup/FTP-Overview/
http://en.wikipedia.org/wiki/Simple_Mail_Transfer_Protocol
http://telecomm.boisestate.edu/itm305l.fall.2008/Lab13.htm
http://neranjara.org/article/title/SMTP_Protocol_Tutorial
http://en.wikipedia.org/wiki/Hypertext_Transfer_Protocol
http://en.wikipedia.org/wiki/Domain_Name_System
https://www.dnsexit.com/support/knowledge_base/how_dns_works_files/dnsbasics.gif
http://en.wikipedia.org/wiki/Routing_Information_Protocol