QoS on a TCPIP Network explain the purpose of QoS on a TCPIP

QoS on a TCP/IP Network

explain the purpose of QoS on a TCP/IP network. Define the basic purpose of IP Precedence, TOS, Diffserv, and ECN functionality. GIve examples how you might use QoS characteritics on your Network.

Solution

Dear student,

here are the answer with complete explanation...

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What is Quality of service...?

In Computer Network QoS stand for Quality of Service.The overall performance of a network is known as Quality of Service. Quality of service is the ability to provide different priority to different applications, users, or data flows, or to guarantee a certain level of performance to a data flow.

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Purpose of QoS on a TCP/IP network

The purose of QoS on a TCP/IP network is to provide preferential delivery service for the applications that need it by ensuring sufficient bandwidth, controlling latency and jitter, and reducing data loss.In TCP/IP network QoS is of particular concern for the continuous transmission of high-bandwidth video and multimedia information.

In TCP/IP Netowrk following characterstics are managed by the QoS...

A. Bandwidth: Bandwidth tells the rate at which traffic is carried by the network.

B. Latency: Lantency menas the delay in data transmission from source to destination.

C: Jitter: In IP networks jitter is the variation in the latency on a packet flow between two systems,     when some packets take longer to travel from one system to the other.

D. Reliability: In TCP/IP reliabiltiy tells the percentage of packets discarded by a router. Packets may be lost during transport due to network congestion and errors.

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Purpose of IP Precedecne

In TCP/IP networking these terms comes under ToS(Type of Service).The ToS field specify a datagram\'s priority and request a route for low-delay, high-throughput, or highly-reliable service.

IP precedence is the old way for type of service(ToS).higher the value of the IP Precedence field means the higher the priority of the IP packet.

Purpose of ToS.........

The ToS defined a mechanism for assigning a precedence to each IP packet, as well as a mechanism to request specific treatment such as high throughput, high reliability or low latency etc.

Purpose of Diffserv........

DiffServ is concerned with classifying packets as they enter the local network.This classification then applies to Flow of traffic where a Flow is defined by 5 elements; Source IP address, Destination IP, Source port, Destination port and the transport protocol.

DiffServ introduces the concept of the DiffServ Code Point (DSCP) that uses the first 6 bits of the TOS field.With DiffServ each router handles each packet differently.

What is the purpose of ECN..?

ECN stand for Explicit Congestion Notification. It is an extension to the TCP/IP protocal.ECN allows end-to-end notification of network congestion without dropping packets. ECN provides some level of performance improvement over a packet drop. With large bulk data transfers, the improvement is moderate, based on the difference between the packet retransmission and congestion-window adjustment.

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How to use QoS characterstics on the Network.?

As a Network administrators we can use QoS to guarantee throughput for mission-critical applications so that our transactions can be processed in an acceptable amount of time.

We can also use QoS to manage User Data Protocol (UDP) traffic. Unlike Transmission Control Protocol (TCP), UDP is an inherently unreliable protocol that does not receive feedback from the network and, therefore, cannot detect network congestion.

And we can also use QoS to manage the priority of applications that rely on UDP, such as multimedia applications, so that they have the required bandwidth even in times of network congestion, but do not overwhelm the network.

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