1. 1 © 2004, Cisco Systems, Inc. All rights reserved. CCNA 2 v3.1 Module 8 TCP/IP Suite Error and Control Messages

2. 222 © 2004, Cisco Systems, Inc. All rights reserved. Purpose of This PowerPoint This PowerPoint primarily consists of the Target Indicators (TIs) of this module in CCNA version 3.1. It was created to give instructors a PowerPoint to take and modify as their own. This PowerPoint is: NOT a study guide for the module final assessment. NOT a study guide for the CCNA certification exam. Please report any mistakes you find in this PowerPoint by using the Academy Connection Help link.

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4. 444 © 2004, Cisco Systems, Inc. All rights reserved. Objectives

5. 555 © 2004, Cisco Systems, Inc. All rights reserved. Internet Control Message Protocol (ICMP)

6. 666 © 2004, Cisco Systems, Inc. All rights reserved. Error Reporting and Error Correction ICMP is an error-reporting protocol for IP.

7. 777 © 2004, Cisco Systems, Inc. All rights reserved. ICMP Message Delivery ICMP messages are encapsulated as data in datagrams in the same way any other data is delivered using IP.

8. 888 © 2004, Cisco Systems, Inc. All rights reserved. Unreachable Networks

9. 999 © 2004, Cisco Systems, Inc. All rights reserved. Ping

10. 10 © 2004, Cisco Systems, Inc. All rights reserved. Detecting Excessively Long Routes Whether the actual path includes too many hops or a circular routing path exists, the packet will eventually reach the end of its life, known as its time-to-live (TTL).

11. 11 © 2004, Cisco Systems, Inc. All rights reserved. ICMP Message Types

12. 12 © 2004, Cisco Systems, Inc. All rights reserved. Destination Unreachable Message

13. 13 © 2004, Cisco Systems, Inc. All rights reserved. Code Values for Destination Unreachable Messages

14. 14 © 2004, Cisco Systems, Inc. All rights reserved. TCP/IP Suite Control Messages Control messages are used to inform hosts of conditions such as network congestion or the existence of a better gateway to a remote network.

15. 15 © 2004, Cisco Systems, Inc. All rights reserved. ICMP Redirect/Change Requests The default gateway of the host may need to use a redirect/change request to inform the host of the best path to a certain network.

16. 16 © 2004, Cisco Systems, Inc. All rights reserved. Clock Synchronization and Transit Time Estimation The ICMP timestamp request message allows a host to ask for the current time according to the remote host. The remote host uses an ICMP timestamp reply message to respond to the request.

17. 17 © 2004, Cisco Systems, Inc. All rights reserved. Address Mask Requirements When a network administrator uses the process of subnetting to divide a major IP address into multiple subnets, a new subnet mask is created.

18. 18 © 2004, Cisco Systems, Inc. All rights reserved. Router Discovery Message When a host on the network boots, and the host has not been manually configured with a default gateway, it can learn of available routers through the process of router discovery.

19. 19 © 2004, Cisco Systems, Inc. All rights reserved. Router Solicitation Message A host generates an ICMP router solicitation message in response to a missing default gateway.

20. 20 © 2004, Cisco Systems, Inc. All rights reserved. Congestion and Flow Control Messages ICMP source-quench messages are used to reduce the amount of data lost from congestion.

21. 21 © 2004, Cisco Systems, Inc. All rights reserved. Summary