April 19, 2023 RE Meyers, Ms.Ed.

CCENT 640-822 ICND1 Exam Topics ReviewCCENT 640-822 ICND1 Exam Topics Review

Describe the Operation of Data Networks:

Network Diagrams and Data Paths

April 19, 2023

DisclaimerDisclaimer

This review is for the exclusive non-profit use by Cisco Academy instructors and students only!Contents of this review were derived from the following

sources under the doctrine of US copyright “Fair Use” section 107:

• Cisco Networking Academy Curricula: Discovery Networking for Home and Small Businesses version 4.x

• Interactive Course Guide, Cisco Learning Institute• CCENT/CCNA ICND 1 Official Exam Certification Guide, 2nd ed.

by Wendell Odom, Cisco Press, 2008; ISBN1-58720-182-2• Cisco Learning Network

https://learningnetwork.cisco.com/docs/DOC-4987• Other references footnoted in individual slide notes area.

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Error ReportingError Reporting

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April 19, 2023

CCENT Exam TopicsCCENT Exam Topics

 Describe the operation of data networksDescribe the impact of applications (Voice over IP and

Video over IP) on a network

https://learningnetwork.cisco.com/docs/DOC-4987

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TCP and UDP ProtocolsTCP and UDP Protocols

Both work at the transport layer of the network models

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TCP: Transport Control ProtocolTCP: Transport Control Protocol

A transport layer protocol used by applications that require guaranteed delivery. Establishes a full duplex virtual connection between two

endpoints. The byte stream is transferred in segments Window size determines the number of bytes of data that

can be sent before an acknowledgement from the receiver is necessary

A “sliding window” provides handling for both timeouts and retransmissions.

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TCP ActionTCP Action

TCP protocol operations is divided into 3 phasesConnection EstablishmentData TransferConnection Termination

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TCP: Connection EstablishmentTCP: Connection Establishment

TCP Connection uses a three-way handshake

1. Client sends a SYN to the server Segment sequence number set

to a random value

2. Server replies with a SYN-ACK Acknowledgment is set to one

more than the received sequence number

3. Client sends an ACK back to the server Sequence number is set to the

received acknowledgement value Acknowledgement number is set

to one more than the received sequence number

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TCP: Data TransferTCP: Data Transfer

Ordered data transferDestination host rearranges according to sequence

numberRetransmssion of lost packets Discards duplicate packetsError-free data transfer Flow control limits the rate a sender transfers data

to guarantee reliable delivery.Congestion control - sliding window

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TCP: Connection TerminatedTCP: Connection Terminated

A typical tear-down requires a pair of FIN and ACK segments from each endpoint When an endpoint

wishes to stop its half of the connection, it transmits a FIN packet

The other end acknowledges with an ACK.

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UDPUDP

User Datagram ProtocolUnreliable data transfer serviceDatagrams may arrive out of order, duplicated, or go

missing without notice. It assumes that error checking and correction is

either not necessary or performed by the application

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TCP vs. UDPTCP vs. UDP

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TCP vs. UDPTCP vs. UDP

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Video On DemandVideo On Demand

Streaming video servers can be found on LANs and WANsBandwidth use is intensiveVery sensitive to data congestion,

latency, and jitter

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Voice Over IPVoice Over IP

A family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks Bandwidth use is intensiveVery sensitive to data congestion, latency, and jitter

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VoIP and VoD DeliveryVoIP and VoD Delivery

VoD and VoIP UDP use UDPAcknowledgments would slow down deliveryRetransmissions are undesirable. If a few packets are missed, the user might hear a slight

break in the sound or a short glitch in the video.

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Quality of ServiceQuality of Service

QoS provides different priority to applications, users, or data VoIP traffic can be tagged to get priority over TCP data

traffic to increase speed of delivery with minimal latency

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