Understanding Layer 2, 3, and 4 protocols

and Cache Load Balancing" by Matthew Syme/Philip Goldie, Addison-Wesley Professional, copyright 2004, ISBN 0131014684. This book will publish in July, 2003. All rights reserved. This chapter is posted with permission from Addison-Wesley Professional.

This chapter includes the following sections:

The OSI seven-layer model – What is a layer?

• The Application Layer (Layer 7)
• The Presentation Layer (Layer 6)
• The Session Layer (Layer 5)
• The Transport Layer (Layer 4)
• The Network Layer (Layer 3)
• The Data Link Layer (Layer 2)
• The Physical Layer (Layer 1)
• Putting all the layers together

Switching at the different layers

• Layer 2 switching
• Layer 3 switching and routing

Understanding Layer 4 protocols
Transport Control Protocol (TCP)

• The lifecycle of a TCP session
  
  1. Initiating a session
  2. Data transfer
  3. Terminating a session

User Datagram Protocol (UDP)

• A simple UDP data flow
  
  • The request
  • The response

Virtual Router Redundancy Protocol (VRRP)

• Layer 2 and 3 redundancy
• The components of VRRP
• VRRP addressing
• VRRP operation

Summary

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