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Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
Aplication and Transport layer-  a practical approach
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Aplication and Transport layer- a practical approach

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This presentation was done for a Networking course. It really shows from a more practical standpoint how the application layer and the transport layer communicates with each other and operates on a …

This presentation was done for a Networking course. It really shows from a more practical standpoint how the application layer and the transport layer communicates with each other and operates on a whole to get the job done. It gives the reader more insight of how the pieces come together in an IT networking world.

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  • 1. Practical Approach - Application Layer with Transport Layer
  • 2. Agenda • Review of models • Application layer interacts with transport / Scenarios • Port Addressing • Responsibilities ofTransport Layer • Tools to help understand and monitor
  • 3. The entire picture – top down approach • OSI – theoretical, reference model • Internet Protocol Suite – practical & widely used, protocol stack on which the internet works. Cisco Systems(2007),Application Layer Functionality and Protocols, Retrieved from http://ciscoserver.eastms.edu/scoleman/ccna1.html
  • 4. Application layer protocols • DNS – Matches/ resolves domain names with IP addresses • HTTP – Used to transfer data between clients/servers using a web browser • SMTP & POP3 – used to send email messages from clients to servers over the internet • FTP – allows the download/upload of files between a client/server • Telnet – allows users to login to a host from a remote location and take control as if they were sitting at the machine (virtual connection) • DHCP – assigns IP addresses, subnet masks, default gateways, DNS servers, to users as they login the network Cisco Systems(2007),Application Layer Functionality and Protocols, Retrieved from http://ciscoserver.eastms.edu/scoleman/ccna1.html
  • 5. Applications – Processes and Services DNS Server • Telnet Server DHCP • Email Server • Web Server • FTP Server DNS Telnet SMTP, POP, IMAP HTTP DHCP FTP In and IT Environment – Companies, Enterprises etc.
  • 6. Examples DHCP Retrieved from http://wintips4u.blogspot.com/2 002/11/dhcp- gujaratikanudo.html TELNET DNS Retrieved from http://www.cisco.com/en/US/products/ hw/optical/ps2006/products_tech_note 09186a008052e85f.shtml Retrieved from http://ciscoserver.eastms.edu/s coleman/ccna1.html
  • 7. Applications need transport Transport layer = LIAISON Protocols at this layer oversee the delivery of data from an application program on one computer to an application program on another computer. More importantly, they act as a liaison between the application-layer protocols and the services provided by the lower layers (network, data link, and physical). Retrieved from http://highered.mcgraw-hill.com/sites/0072397020/student_view0/chapter3/ Stallings (2010), Each application within a host must have an address that is unique within the host; this allows the host-to-host protocol (TCP) to deliver data to the proper process.These latter addresses are known as Ports. How is the application identified? –Transport layer uses application identifier – PORTS Internal address reserved for a specific application. It determines which application layer protocols is used.
  • 8. Application connects to transport layer
  • 9. Link layer Network IP Internet TCP port UDP port 20 21 80 69 53 FTP HTTP TFTP DNS Application TCP UDP Transport Socket interface Socket  IP address & TCP/UDP port
  • 10. PORT ADDRESSINGTRANSPORT LAYER • Many common application have default port assignments. • Port numbers are assigned in different ways depending on whether it is a request or response. • The source port in a segment of a client request is generated randomly once it does not conflict with existing used ports. • The destination port is either assigned by default or manually IANA assignment ports – International Assigned Numbers Authority http://www.iana.org/ • 0 to 1023 - Well Known (Contact) Ports • 1024 to 49151 – Registered Ports • 49152 to 65535 – Private and/or Dynamic Ports
  • 11. Responsibility ofTransport Layer – Port Addressing Retrieved from http://ciscoserver.eastms.edu/scoleman/ccna1.html
  • 12. Other responsibilities - TRANSPORT Layer • Segmentation • Session Multiplexing • Identification of different applications • Sequencing • Flow Control • Connection Oriented • Reliability RELIABLE BEST EFFORT Connection Type Connection-oriented Connectionless Protocol TCP UDP Sequencing Yes No Uses Email / File Sharing /Downloading Voice Streaming / Video Streaming/ Online Gaming
  • 13. TCP / UDP TCP TRANSPORT LAYER UDP TCP FTP – 20-21 Telnet – 23 SMTP – 25 DNS – 53 (BothTCP & UDP) HTTP – 80 UDP DHCP – 67 & 68 DNS - 53 TFTP – 69 www.iana.org RFC 1700 - http://www.cse.ohio-state.edu/cgi- bin/rfc/rfc1700.html
  • 14. NETWORK UTILITIES TCP – 3WAY HANDSHAKE INTCP / Connection Oriented CONNECTION ESTABLISHMENT Retrieved from – http://blogs.ixiacom.com/ixia-blog/tcp-portals-the- handshakes-a-lie/
  • 15. Protocol Analyzer Connection Request Retrieved from - http://www.highteck.net/IT/Transport/Livello_OSI_Transport.html
  • 16. Protocol Analyzer • Connection confirmation Retrieved from - http://www.highteck.net/IT/Transport/Livello_OSI_Transport.html
  • 17. Protocol Analyzer • Acknowledgement of confirmation Retrieved from - http://www.highteck.net/IT/Transport/Livello_OSI_Transport.html
  • 18. NetStat • Examine openTCP connections over the network host • UnexplainedTCP connections which can pose a threat by consuming resources Retrieved from - http://www.highteck.net/IT/Transport/Livello_OSI_Transport.h tml
  • 19. Troubleshooting Network Utility tools • FIDDLER • Microsoft Network monitor
  • 20. SUMMARY • When we use apps over the internet the application layer protocols takes the request down to lower layers. • The transport layer is the liaison, responsible for delivering the segments to lower layer. • A port is what connects the application layer to the transport layer.Tells the transport layer which protocol is speaking and whether to use tcp/udp to deliver. • TCP – Reliable connection oriented • UDP – Connectionless • Application protocols + ports tells us whetherTCP/UDP to use. • Tools to use for monitoring and troubleshootingTCP connections.
  • 21. REFERENCES Coleman S.. (2007), Application Layer Functionality and Protocols, In Network Fundamentals CCNACisco Systems– (Chapter 3) Retrieved from http://ciscoserver.eastms.edu/scoleman/ccna1.html Stallings ,W. (2010), Cryptography and Network Security, Fifth Edition William Stallings Prentice Hall. http://www.highteck.net/IT/Transport/Livello_OSI_Transport.html http://wintips4u.blogspot.com/2002/11/dhcp-gujaratikanudo.html http://www.cisco.com/en/US/products/hw/optical/ps2006/products_tech_note09186a008052e85f.shtml http://blogs.ixiacom.com/ixia-blog/tcp-portals-the-handshakes-a-lie/ http://www.iana.org/numbers

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