Quality of service
Quality of service is the management of communication policies and traffic characteristics such as priority, reliability, latency, bandwidth, jitter, and loss.
Acing the CCNA Exam: Volume 2 Advanced Networking and Security
Quality of service is the classification, marking, queuing, and scheduling of network traffic to manage performance characteristics such as delay, jitter, bandwidth, and loss.
- How it is used
- Prioritizes voice, video, and other important traffic when congestion threatens user experience.
- How deep it goes
- Explains classification, marking, queuing, and scheduling, but stops short of detailed policy configuration and wireless QoS internals.
- Examples
- Uses IP telephony, Zoom calls, file downloads, voice VLAN configuration, DSCP and PCP markings, and FIFO queue behavior.
- What you can do after
- Configure and verify a voice VLAN, and evaluate how QoS classifies, marks, queues, and schedules congested traffic.
Acing the CCNA Exam: Volume 1 Fundamentals and Protocols
Quality of Service is the classification and prioritization of network traffic to provide differentiated service levels.
- How it is used
- Prioritizes delay-sensitive traffic within network forwarding.
- How deep it goes
- Defines DSCP and ECN in the IPv4 header, but stops short of configuration or implementation procedures.
- Examples
- Uses Zoom calls and other voice or video traffic to illustrate delay-sensitive service.
- What you can do after
- Evaluate how DSCP and ECN support prioritization of delay-sensitive IPv4 traffic.
Read how Acing the CCNA Exam: Volume 1 Fundamentals and Protocols explains quality of service →
Related concepts
- markinghas part · Marking is the process of setting packet or traffic header fields to encode classification information for network policy enforcement.
- classifierhas part · A classifier is a predictive computational model that assigns inputs to one or more discrete classes or categories.
- differentiated services code pointuses · The Differentiated Services Code Point is a six-bit field in an IP header that identifies a packet’s desired forwarding treatment.
- meanaddresses · A mean is a measure of central tendency, calculated as the arithmetic average of values or, for a random variable, as the probability-weighted average of its possible values.
- class-based weighted fair queuinguses · Class-Based Weighted Fair Queuing is a packet-scheduling technique that assigns traffic classes to queues and guarantees each queue a configured minimum share of bandwidth during congestion.
- low latency queuinguses · Low Latency Queuing is a QoS scheduling technique that gives selected traffic strict priority treatment while providing bandwidth allocation for other classes.
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