Copyright © 2000, Cisco Systems, Inc. 1 © 2000, Cisco Systems, Inc. Introduction to Quality of Service Introduction to Quality of Service Copyright © 2000, Cisco Systems, Inc. 2 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Objectives Objectives Upon completion of this module, you will be able to perform the following tasks: • Explain the significance of Quality of Service (QoS) • Describe new Quality of Service (QoS) features in Cisco IOS 12.1 • Explain which problems QoS solves The purpose of this module is to quickly survey the new Quality of Service (QoS) features in Cisco IOS 12.1 and to describe the problems they solve Copyright © 2000, Cisco Systems, Inc. 3 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Topics Topics QoS overview New QoS features Quick look at Diff Serv framework Copyright © 2000, Cisco Systems, Inc. 4 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Why Is QoS So Important? Why Is QoS So Important? QoS: • Allows the integration of data, voice, and video over the network • Mission-critical traffic can be prioritized over non-critical traffic –Certain business applications –Voice, SNA traffic • Can prioritize different groups of users , such as finance, sales, or suppliers The Cisco IOS QoS features enable networks to control and predictably service a variety of networked applications and traffic types. Implementing Cisco IOS QoS in your network promotes the following: • Control over resources—You control which resources (bandwidth, equipment, wide-area facilities, and so on) are being used. For example, you can limit bandwidth consumed over a backbone link by File Transfer Protocol (FTP) transfers or give priority to an important database access. • Tailored services—If you are an Internet Service Provider (ISP), the control and visibility provided by QoS enables you to offer carefully tailored grades of service differentiation to your customers. • Coexistence of mission-critical applications. Cisco QoS features make certain of the following: • That your WAN is used efficiently by mission-critical applications that are most important to your business. • That bandwidth and minimum delays required by time-sensitive multimedia and voice applications are available. • That other applications using the link get their fair service without interfering with mission-critical traffic. Moreover, in implementing QoS features in your network, you put in place the foundation for a future fully integrated network. http://cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/qos_c/qcdintro.htm Copyright © 2000, Cisco Systems, Inc. 5 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Where Do We Use QoS? Where Do We Use QoS? Low bandwidth links Managing bandwidth Application service levels • Voice • Mission-critical applications IP network replacing ATM infrastructure Differentiated levels of service Internet The slide lists some of the places where QoS is being applied today. QoS is important to those using low bandwidth links, to protect voice or mission-critical traffic on those links, especially in the event of congestion. Control and protection of voice and mission-critical traffic can also be important to the customer over higher speed links. Sometimes QoS is desired because IP networking is replacing ATM, and QoS is something valuable that ATM has to offer, and the customer wishes to also have comparable capabilities with IP networking. Copyright © 2000, Cisco Systems, Inc. 6 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box What Is QoS? What Is QoS? QoS: • Allows a network to provide better service to selected traffic • Enables the network to handle both mission-critical and non-critical traffic on the same infrastructure • Is not a magic solution to every problem QoS refers to the ability of a network to provide better service to selected network traffic over various underlying technologies including Frame Relay, ATM, Ethernet and 802.1 networks, Synchronous Optical Network (SONET), and IP-routed networks. In particular, QoS features provide better and more predictable network service by: • Supporting dedicated bandwidth • Reducing loss • Avoiding and managing network congestion • Shaping network traffic • Setting traffic priorities across the network The slide also reminds us that QoS is not necessarily a solution to every problem. With low bandwidth links, there comes a point where you just simply need more bandwidth, and nothing else will really work. If your network is poorly designed, it may have high latency, many hops, or be unstable — and QoS is not going to fix that or work in spite of that. Think of QoS as taking a well-tuned network and making it work even better, not as a quick fix to all sorts of problems. Applications can sometimes be changed to vastly improve performance. On the other hand, commercial applications generally cannot be changed, in which case we do what we can to improve things on the network side. Some performance issues are server sizing or tuning issues. QoS cannot do much in such circumstances. http://cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/qos_c/qcdintro.htm Copyright © 2000, Cisco Systems, Inc. 7 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Applying QoS Applying QoS Mobile User Home User Hunt Group Network Management FR, xDSL Small Office Hosting PSTN Internet AAA Backbone Access Customer Premises Equipment Distribution Layer or PoP Determine policy and service levels implementation: • Classifying • Marking • Policing / Shaping • Queuing / Scheduling • Congestion Avoidance The slide shows a large network, with access, distribution, and core layers. This could be a view of a large Enterprise network or a view of a Service Provider network. This graphic introduces some of the basic terminology and concepts of QoS in the next slides. Copyright © 2000, Cisco Systems, Inc. 8 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Topics Topics QoS overview New QoS features • New features covered in this section’s modules • Other related new features Quick look at Diff Serv framework Copyright © 2000, Cisco Systems, Inc. 9 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box Class-Based Weighted Fair Queuing (CBWFQ) Class-Based Weighted Fair Queuing (CBWFQ) Capabilities: • User-defined traffic classes based on match criteria • Classes assigned bandwidth, queue limits or drop policy Benefits: • Bandwidth allocation • Finer granularity and scalability • Modular QoS Command Line Interface (CLI) is easier to use Class-Based Weighted Fair Queuing (CBWFQ) allows the user to define traffic classes based on customer-defined match criteria such as access control lists (ACLs), input interfaces, protocol, and QoS label. For example, a class might consist of a team working on a certain project or a class can be created for the important mission-critical applications, for example, enterprise resources planning (ERP). When the traffic classes have been defined, they can be assigned a bandwidth, queue limit, or drop policy such as Weighted Random Early Detection (WRED). • Bandwidth allocation —CBWFQ allows you to specify the exact amount of bandwidth to be allocated for a specific class of traffic. Accounting for available bandwidth on the interface, you can configure up to 64 classes. • Finer granularity and scalability—CBWFQ allows you total flexibility to define a class based on ACLs and protocols or input interfaces, thereby providing finer granularity. • Support in the modular command-line interface (CLI) framework—CBWFQ is supported in the new modular CLI framework, which is a new, template-based CLI. This new modular CLI eases the configuration of CBWFQ by introducing the class-map, service-map and policy-map approach. This “virtual template” eases the constant configuration of policies per interface, and reduces the configuration by allowing the service maps to be assigned to each interface – without reconfiguring the match criteria/ACLs and policies. • WRED supported as a drop policy—CBWFQ supports WRED as a drop policy per class, thus allowing you to provide differentiated service within a class. This feature is supported on all platforms that WFQ is supported on, in other words, the Cisco 7200, 4700, 4500, 3600, and 2600 series, and so on. First appearance in a Cisco IOS software T release: 12.0(5)T. http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/cbwfq.htm Copyright © 2000, Cisco Systems, Inc. 10 © 2000, Cisco Systems, Inc. www.cisco.com Econ_0385_02_010.ppt Keep All Graphics Inside This Box IP Real-Time Transport Protocol (RTP) Priority IP Real-Time Transport Protocol (RTP) Priority Capabilities: • Provides strict priority to time-sensitive traffic • Extends functionality of the former IP RTP Reserve feature • Especially useful for voice traffic • Also called PQ-WFQ The IP RTP Priority feature provides a strict priority queue for delay-sensitive packets such as those in Voice over IP. Voice traffic can be identified by the RTP port numbers and classified into a priority queue set up by the IP RTP Priority mechanism. This feature can be turned on in conjunction with either Weighted Fair Queuing (WFQ), or Class-Based Weighted Fair Queuing (CBWFQ), on the same outgoing interface. When used in conjunction with CBWFQ, the “ip rtp priority” command provides strict priority to Voice. Additionally, CBWFQ can also be used to set up classes (for example, gold/silver/bronze) for other types of traffic (for example, SNA or PeopleSoft) that require dedicated bandwidth and better servicing than “best- effort”, but not as strict as Priority Queuing. CBWFQ can also support flow-based WFQ within the “Default CBWFQ Class”, if so configured. IP RTP Priority extends, and will obsolete, the functionality offered by the feature IP RTP Reserve. By specifying a range of UDP RTP ports, the user ensures that voice traffic is guaranteed strict priority service over any other queues or classes using the same output interface. Strict priority means that if packets exist in the priority queue, they are de-queued and sent first—before packets in other queues are dequeued. Because voice packets are small in size and the interface may have larger data packets requiring servicing simultaneously, the Link Fragmentation and Interleaving (LFI) feature, also known as Multi-link PPP Fragmentation, is recommended to be configured for lower-speed interfaces. LFI will fragment the larger data packets (for example, FTP at 1500 bytes) so the smaller voice packets can be interleaved among the data fragments, thus ensuring that voice traffic is serviced with minimal delay. http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/iprtp.htm [...]... and measurement of enterprise and service provider networks With the increasing importance of mission-critical applications and networks that link global enterprises, customers are demanding SLAs that guarantee minimumacceptable levels of service The SA Agent provides a reliable mechanism to accurately monitor and measure the key metrics in SLAs The SA Agent allows you to measure and monitor the following:... can also be used to trigger additional collection of time delay statistics Capabilities of RTR include: • User Datagram Protocol (UDP) response time operation • TCP connect time operation • Type -of- service support for the Internet Control Message Protocol (ICMP) operations • Loose source routing (LSR) in the ICMP path operation The Service Assurance Agent (SAA) is both an enhancement to and a new name... CoS with MPLS requires no configuration of end -to- end VCs for each class of service This advantage is especially beneficial when MPLS CoS support is integrated in conjunction with an MPLS Virtual Private Network (VPN) service Traditional methods of configuring IP CoS with ATM would require configuring and provisioning a separate end -to- end VC for each class of service for each VPN • Flexibility without... http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/ 120newft/120t/120t5/saaoper.htm#xtocid203251 Copyright © 2000, Cisco Systems, Inc 16 Subnetwork Bandwidth Manager (SBM) Capability: • SBM maps Layer 3 QoS protocol such as Resource Reservation Protocol (RSVP) to MAC layer in Ethernet 802.1P/Q LANs • Router automatically a client, optionally can participate in bidding to be DSBM Benefit: • SBM completes the Layer 3 end -to- end... protocol for Resource Reservation Protocol (RSVP)-based admission control for LANs It provides a method for mapping a Layer 3 protocol such as RSVP to Ethernet LANs It describes the operation and mapping of an RSVP-enabled host requesting bandwidth with link-layer devices such as switches and bridges to support reservation of LAN resources for RSVP-enabled data flows RSVP is a Layer 3 signaling protocol... • Not limited to UDP port numbers—Because you can configure the priority status for a class within CBWFQ, you are no longer limited to UDP port numbers to stipulate priority flows Instead, all of the valid match criteria used to specify traffic for a class now apply to priority traffic • Admission control—By configuring the maximum amount of bandwidth allocated for packets belonging to a class, you... assigned for each service class per destination Tag Distribution Protocol/Label Distribution Protocol (TDP/LDP) is used to set up the hop-by-hop VCs and to manage which class-based queue corresponds to which VC WFQ is used to define the amount of link bandwidth available to each service class and thus differentiate between classes based on delay The edge LSRs then schedule packets by class using WFQ... on a backbone built purely of routers The following benefits are realized when IP CoS is implemented on a backbone of ATM switches using MPLS • Efficient resource allocation—WFQ is used to allocate bandwidth on a per-class and per-link basis Classes of traffic are guaranteed a percentage of link bandwidth, thereby maximizing the transport of paid traffic • No connections to configure for CoS – Implementing... between classes based on drop probability at the edge and core of an MPLS network, and WFQ is used to differentiate between classes based on delay at the edge and core of an MPLS network In the case where LSRs reside in the core of the MPLS backbone, the LSRs are either Cisco 7200 or 7500 routers running MPLS software IP packets come into the edge of the MPLS network and the edge LSRs classify the IP packets... allows each precedence level to be associated with its own ATM PVC This is useful for DSL Platforms/Considerations: • Operates on Cisco 7500 and 7200 series • Requires ATM PA-A3 • Phase I of the IP to ATM CoS appeared in Cisco IOS software Release 11.1(22)CC • First appearance in a Cisco IOS software T release: 12.0(3)T http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t3/ipatmcs2.htm . Systems, Inc. 1 © 2000, Cisco Systems, Inc. Introduction to Quality of Service Introduction to Quality of Service Copyright © 2000, Cisco Systems, Inc completion of this module, you will be able to perform the following tasks: • Explain the significance of Quality of Service (QoS) • Describe new Quality of Service