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Address Resolution
Explain how ARP and ND enable communication on a network
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The third CCNA course describes the architectures and considerations related to designing, securing, operating, and troubleshooting enterprise networks – including wide area network (WAN) technologies & quality of service (QoS) mechanisms for secure remote access, along with software-defined networking, virtualization, & automation concepts supporting network digitization.
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About Lesson

UDP Overview

Explain characteristics of UDP.

UDP Features

UDP features include the following:

  • Data is reconstructed in the order that it is received.
  • Any segments that are lost are not resent.
  • There is no session establishment.
  • The sending is not informed about resource availability.

UDP Header

  • The UDP header is far simpler than the TCP header because it only has four fields and requires 8 bytes (i.e. 64 bits).

UDP Header Fields

  • The table identifies and describes the four fields in a UDP header.
Description Field
Source Port A 16-bit field used to identify the source application by port number.
Destination Port A 16-bit field used to identify the destination application by port number.
Length A 16-bit field that indicates the length of the UDP datagram header.
Checksum A 16-bit field used for error checking of the datagram header and data.

Applications that use UDP

  • Live video and multimedia applications – These applications can tolerate some data loss but require little or no delay. Examples include VoIP and live streaming video.
  • Simple request and reply applications – Applications with simple transactions where a host sends a request and may or may not receive a reply. Examples include DNS and DHCP.
  • Applications that handle reliability themselves – Unidirectional communications where flow control, error detection, acknowledgments, and error recovery is not required, or can be handled by the application. Examples include SNMP and TFTP.

   

Other related topics

 

Topic Title Topic Objective
Transportation of Data Explain the purpose of the transport layer in managing the transportation of data in end-to-end communication.
TCP Overview Explain characteristics of TCP.
UDP Overview Explain characteristics of UDP.
Port Numbers Explain how TCP and UDP use port numbers.
TCP Communication Process Explain how TCP session establishment and termination processes facilitate reliable communication.
Reliability and Flow Control Explain how TCP protocol data units are transmitted and acknowledged to guarantee delivery.
UDP Communication Compare the operations of transport layer protocols in supporting end-to-end communication.

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