• Chapter 1: Cisco VOIP Implementations
• Chapter 2: IP Quality of Service
• Chapter 3: Classification, Marking, and NBAR
• Chapter 4: Congestion Management and Queuing
• Chapter 5: Congestion Avoidance, Policing, Shaping, and Link Efficieny Mechanisms
• Chapter 6: Implementing QoS Pre-Classify and Deploying End-to-End QoS
• Chapter 7: Implementing AutoQoS
• Chapter 8: Wireless LAN QoS Implementation
• Chapter 9: 802.1x and Configuring Encryption and Authentication
• Chapter 10: WLAN Management

Chapter 2: IP Quality of Service

QoS concerns:

• Available bandwidth
• End-to-end delay
• Jitter (delay variation)
• Packet loss

Common solutions to address bandwidth availability:

• Increase available bandwidth
• Classification and prioritization (QoS)
• Header and/or payload compression
• Increase interface buffers

Implementing QoS

Step 1: Identifying traffic types and requirements

• Perform audits during busy and slow periods
• Determine the business importance of each application
• Define service levels for each traffic class

Step 2: Classifying traffic

• VOIP
• Mission-critical
• VOIP signaling (call setup/tear-down)
• Interactive applications
• Best-effort
• "Scavenger" (unimportant)

Step 3: Defining policies

• Assign minimum and maximum bandwidth for each class
• Assign each class a relative priority
• Assign queuing type

QoS Models

Best-Effort

The best-effort model is simple the absence of QoS policy.

Integrated Services (IntServ)

Resource Reservation Protocol (RSVP) is used to reserve a minimum amount of bandwidth along an end-to-end path.

Provides explicit end-to-end admission control per request (flow).

Substantial overhead is involved; poor scalability.

Differentiated Services (DiffServ)

DiffServ is defined in RFCs 2474 and 2475.

QoS is configured and performed separately at each hop in the path.

Traffic is administratively grouped into classes with different qualities of service.

The DiffServ model sacrifices end-to-end service guarantee in favor of scalability.

QoS Implementation

Legacy CLI

Non-modular, tedious configuration at the interface level.

Modular QoS CLI (MQC)

MQC provides a structured framework for defining classes and policies.

1. Traffic classes are defined with the class-map command
2. QoS policies are linked to traffic classes with the policy-map command
3. Policies are applied to interfaces with the service-policy command

show class-map and show policy-map can be used to verify MQC configurations.

AutoQoS

AutoQoS facilitates the automatic generation and application of QoS policies.

AutoQoS Discovery can perform automatic classification using NBAR and CDP.

Perceived bandwidth must be configured accurately on interfaces with the bandwidth statement.

First generation AutoQoS is configured with auto qos voip on an interface, only automating QoS configuration for VOIP traffic.

Modern (Enterprise) AutoQoS is configured with auto discovery qos to enable NBAR traffic analysis and auto qos for policy construction.

SDM QoS Wizard

The SDM Wizard is a GUI frontend for QoS configuration using three built-in classes (VOIP, business-critical, and best-effort).

Allows for periodic monitoring of QoS performance.