QoS Overview

The goal of this guide is to provide you with a quick overview of QoS concepts and to show you how to configure an easy and complex configuration. It is by no means a comprehensive guide on configuring QoS. For detailed information about QoS features, configuring, migrating, and example scenarios, see the SteelFusion Core Management Console User’s Guide and the SteelHead Deployment Guide.

If you want to skip the theory and learn how to configure QoS, go to:

Note: This document doesn’t describe how to migrate QoS from earlier versions of RiOS to RiOS 9.x. Because RiOS 8.x and earlier does not use the new concepts (that is, networks, uplinks, and QoS profiles), it can be easier to create a new QoS configuration in RiOS 9.x, or modify the default classes, than to migrate an existing QoS configuration. You should carefully plan your QoS migration and only perform it during nonproduction hours. After you finish the migration, make sure you closely analyze the migrated QoS configuration for any repeated QoS profiles, classes, and rules.

RiOS 9.x not only has a new GUI but it also introduces new building blocks for configuring QoS, such as application definitions, QoS profiles, and a network typology consisting of networks, sites, and uplinks.

RiOS 9.x gets rid of the repetitive configuration steps for classes, sites, and rules. You no longer have to choose between basic and advanced QoS nor do you have to manually compute the oversubscription factor—RiOS 9.x does this automatically.

For QoS to shape and prioritize traffic, it needs to know about the network; that is, its uplinks and the bandwidths available for them. Instead of configuring everything for each QoS instance, you configure building blocks and put them together as needed.

If you have more than three SteelHeads in your QoS configuration, you should use the SteelCentral Controller for SteelHead (SCC) to configure and manage QoS. The SCC is a great tool to manage configurations and simplify the rollout. RiOS 9.x is all about making things easy.

This first building block is applications. Basically applications are what you care about when configuring QoS. With RiOS 9.x they are defined as objects independent from QoS. Treating applications as objects allows for grouping of applications on multiple characteristics. In RiOS 9.x, you can use an application group like Business Critical or Business Standard in a QoS rule, which means you can have a single rule taking care of many applications. This simplifies the configuration and minimizes the number of rules needed, providing better scalability.

In RiOS 9.x applications must be defined before you can use them in a QoS rule.

Often QoS classes and rules are the same for many sites. Let's put them into a second building block and call it a QoS profile.

Classes and rules are mandatory for QoS. You need to classify traffic for shaping, prioritization, and steering it into a hierarchy. For this you need rules that are based on applications or, better yet, groups of applications.

Starting with RiOS 9.5, SteelHeads come with a default QoS configuration, including a set of classes that are based on Riverbed best practices. You can add QoS rules to the default classes to classify traffic, which results in a working QoS configuration for inbound and outbound traffic on the SteelHead. If you require only one QoS profile, using the default classes can simplify QoS configuration. For more information, see the QoS Overview section in the SteelHead Management Console User’s Guide.

Instead of modifying the default classes, you can also create a new QoS profile based on a blank template, as shown in Simple QoS Configurationor create multiple profiles, as shown in Complex QoS Configuration.

In RiOS 9.x, QoS classes use numbers for latency priorities, instead of names. This table summarizes the QoS class latency priorities in descending order.

Latency Priority	Example
1 = Real time	Typically, applications such as VoIP and video conferencing are given real-time latency priority
2 = Interactive	Citrix, RDP, Telnet, and SSH
3 = Business critical	Thick client applications, ERPs, CRMs
4 = Normal priority	Internet browsing, file sharing, email
5 = Low priority	Typically, applications that are delay insensitive, such as FTP, backup, replication, and other high-throughput data transfers; recreational applications such as audio file sharing
6 = Best effort	Lowest priority

A QoS rule is part of a profile and assigns an application or application group to a QoS class. If a QoS rule is based on an application group, it counts as a single rule.

Rules in the QoS rules table are applied from top to bottom. Make sure that you place the more granular QoS rules at the top of the QoS rules list.

Connect these building blocks by assigning a QoS profile to a network and site. The SteelHead then has all the necessary information to perform QoS.

The SteelHead needs to know about the networks by name and the sites it can reach. Within the sites it needs to know the subnets—it’s local subnets as well as the ones in the sites. It also needs to know about the sites—its own site, where it's located, and the remote ones that are connected to the networks. This information includes in-path interfaces, gateways, and the bandwidths to calculate how much bandwidth is available to reach its peers in the sites.

All this information can be collected into one building block that is the network topology.

Creating networks is simple. They consist of:

• Public network - This setting tells the SteelHead if the network is a public or a private network. (The public network option only takes effect if you configure secure transport using the SCC.)

Sites have more characteristics. They have uplinks to networks and the bandwidth for those uplinks. There are three types of sites:

• Local site - This site is the SteelHead you're configuring. For QoS you only need to configure the subnets and uplinks that the SteelHead is connected to. You can ignore the other site attributes.

• Remote sites - These sites are defined in the Subnets field by their IP addresses, their assigned QoS profile, and their uplinks to the networks.

• Default site - This site is the catch-all site for all remaining traffic that isn't destined in a configured site. This site only exists in the SteelHead; it is not present in the SCC. In the SCC the default site is not visible and the default behavior of traffic is determined through the internet traffic setting in a site.

Uplinks connect a site to a network. A site can have single or multiple uplinks to the same network and can connect to multiple networks. You must specify, per uplink, the bandwidth available for uploading and downloading data. The bandwidth values are used by RiOS to calculate the bandwidth available for traffic for inbound and outbound QoS configurations. In combination with the bandwidth configuration of the local sites uplink, the SteelHead automatically calculates the oversubscription factor in case the sum of the bandwidths of the remote sites to a network is greater than the bandwidth of the local site to the same network.

To configure QoS you need to complete these tasks:

1. Check for application definitions - Check if the applications you want to apply to QoS are defined in the Application Flow Engine (AFE). If they aren’t already defined, you must configure them and assign them to an application. For details, see Defining applications.

2. Configure the default QoS classes or add new profiles - QoS profiles are the classes and rules that prioritize and shape the applications. QoS profiles are assigned to sites so you must configure QoS profiles before you configure networks and sites. For details, see Creating QoS profiles.

3. Configure the topology (networks, sites, and uplinks) - Define the network and set up the local and remote sites for QoS. Configure the bandwidth to and from the sites. For details, see Configuring the topology.

4. Assign the profiles to the sites - Select an inbound or outbound QoS profile for the sites. For details, see Configuring the topology.

5. Enable QoS on the SteelHead. Finally, enable QoS on the SteelHead and make sure the wan0_0 interface has inbound and outbound QoS enabled. For details, see Enabling QoS on the SteelHead.

If you plan to configure more than three SteelHeads, we strongly recommend that you use the SteelCentral Controller for SteelHead (SCC) 9.0 or later to configure QoS. The SCC enables you to configure QoS once and then send it to multiple SteelHeads instead of connecting to each SteelHead and repeating the configuration steps for every SteelHead in your network.