Free CCNA Routing | Part 7 - Introduction to QoS

Free CCNA Routing | Part 7 - Introduction to QoS

Welcome to the Free CCNA Training Course. This series is for anyone who wants to build on their basic network skills, and even pass the CCNA 200-301 exam.

Section 2 of this series covers Layer-3/Routing. This covers topics like general routing, routing protocols, OSPF, and QoS (Quality of Service).

The website has additional links for further study to take you to the next level. Links are at the end of the description.

In this video, we’re going to cover:
0:00 Overview
0:37 What is QoS?
3:48 Application Traffic
7:21 Classification and Marking
15:14 Cisco’s MQC
22:48 MQC - Markings

QoS (Quality of Service) is a set of tools that help us to tune the network. If there’s congestion on the network, QoS can prioritize important traffic (such as voice and video) over unimportant traffic. It can also be used for rate-limiting (shaping or policing).

Real-time traffic needs to be delivered steadily and on time. Other traffic types, like HTTP, are not as concerned with steady delivery.

There are four traffic characteristics that we need to be aware of:
Bandwidth - The amount of traffic to transfer, in bits per second
Loss - The amount of traffic that doesn’t make it to its destination
Latency - The time it takes to get traffic from one endpoint to another (similar to RTT)
Jitter - The variance in latency

Each device makes its own QoS decisions. This is called Per Hop Behaviour (PHB). Even so, all devices must work together to reach a common goal. One way they can make it easier on each other is to mark packets. This makes it easier for other devices to classify traffic and decide how to handle it.

In a modern network, marking happens in the DSCP (DiffServ) field within the IP header, or in the CoS field in the Ethernet header. Older networks will use the ToS header in the IP header.

QoS is configured on a Cisco router using their Modular QoS CLI (MQC). This is just the configuration hierarchy that the configuration is organised into.

Interesting traffic is identified in a class-map. This may use an access-list or NBAR to help identify traffic. Then policy-maps apply actions to the traffic in these classes. And finally, a service-policy applies the policy-map to an interface, in an in or out direction.

QoS Mini-series

Thank you for watching out Free CCNA Training Course

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[ProjectManagementPMI]

i really love the animations used during explanation

[deondoc]

Thank you answers to simple of OoS and the lab examples helped even more.

[anchalgupta]

Make some video on detailed mpls traffic engineering ...