Tcp_IP1 - Understanding TCP/IP A-1 A P P E N D I X A...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Understanding TCP/IP A-1 A P P E N D I X A Understanding TCP/IP Introduction To fully understand the architecture of Cisco Centri Firewall, you need to understand the TCP/IP architecture on which the Internet is based. This appendix discusses the TCP/IP architecture and provides a basic reference model that can help you understand how Cisco Centri Firewall operates. It explains TCP/IP terminology and describes the fundamental concepts underlying the TCP/IP protocol suite. We begin by providing a common frame of reference to use as a basis for the rest of the discussion contained in this appendix on TCP/IP and Cisco Centri Firewall. What is an Architectural Model? An architectural model provides a common frame of reference for discussing Internet communications. It is used not only to explain communication protocols but to develop them as well. It separates the functions performed by communication protocols into manageable layers stacked on top of each other. Each layer in the stack performs a specific function in the process of communicating over a network. Generally, TCP/IP is described using three to five functional layers. To describe TCP/IP based firewalls more precisely, we have chosen the common DoD reference model , which is also known as the Internet reference model . Figure A-1 illustrates the Internet reference model. A-2 Securing Your Network with the Cisco Centri Firewall What is an Architectural Model? Figure A-1 The DoD Protocol Model This model is based on the three layers defined for the DoD Protocol Model in the DDN Protocol Handbook, Volume 1 . These three layers are as follows: • network access layer • host-to-host transport layer • application layer An additional layer, the internetwork layer, has been added to this model. The internetwork layer is commonly used to describe TCP/IP. The following section explains how network protocols work, and it defines the basic terminology that we use to discuss TCP/IP and Cisco Centri Firewall. Another standard architectural model that is often used to describe a network protocol stack is the OSI reference model. This model consists of a seven layer protocol stack (see Figure A-2). Process/application layer consists of applications and processes that use the network. 4 3 2 1 Host-to-host transport layer provides end-to-end data delivery services. Internetwork layer defines the datagram and handles the routing of data. Network access layer consists of routines for accessing physical networks. NM6130 Understanding TCP/IP A-3 What is an Architectural Model? Figure A-2 The OSI Protocol Reference Model No additional information or explanation for this reference model will be included within this guide because very few firewalls implement this model. For additional information on this reference model consult Chapman, D. B., and Elizabeth D. Zurichy, Building Internet Firewalls , Sebastopol:O'Reilly & Associates, Inc., September 1995. (See Appendix B.) or Heywood, D., Networking with Microsoft TCP/IP...
View Full Document

This note was uploaded on 08/08/2011 for the course CS 310 taught by Professor Aartisingh during the Spring '11 term at National Institute of Technology, Calicut.

Page1 / 16

Tcp_IP1 - Understanding TCP/IP A-1 A P P E N D I X A...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online