Tài liệu Infrastructure Quality of Service pptx

Copyright © 2000, Cisco Systems, Inc. 1 © 2000, Cisco Systems, Inc. Infrastructure Quality of Service Infrastructure Quality of Service Copyright © 2000, Cisco Systems, Inc. 2 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Objectives Objectives Upon completion of this module, you will be able to perform the following tasks: • Describe the purpose of classification and marking • Explain IP Precedence and Diff-Serv • Describe Quality of Service policy using Modular QoS Command Line Interface (CLI) • Explain Network Based Application Recognition (NBAR) Copyright © 2000, Cisco Systems, Inc. 3 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Objectives Objectives • Describe forms of packet, frame, or cell marking • Describe the purpose and benefits of Resource Reservation Protocol (RSVP) and Common Open Policy Service (COPS) • Explain briefly how RSVP and COPS work • Describe each of the Cisco QoS management products • Identify the functions of each product • Recommend a full QoS management architecture Copyright © 2000, Cisco Systems, Inc. 4 Quality of Service Classification and Marking Quality of Service Classification and Marking © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_001.ppt Copyright © 2000, Cisco Systems, Inc. 5 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Objectives Objectives Upon completion of this module section, you will be able to perform the following tasks: • Describe the purpose of classification and marking • Explain IP Precedence and Diff-Serv • Describe QoS policy using Modular QoSCLI • Explain Network Based Application Recognition (NBAR) • Describe forms of packet, frame, or cell marking The purpose of the lesson is to quickly survey the new Classification and Marking features in Cisco IOS 12.1, and to describe the problems they solve. Copyright © 2000, Cisco Systems, Inc. 6 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Enterprise QoS Enterprise QoS 30 Kbps 300 Kbps • Remote site has a 350 Kbps CIR FR link • Bursty applications contending for bandwidth reduce collective throughput. Customer needs better throughput • What can we do to improve things? These are charts from Ganymede Chariot used in a lab based on FIFO (no queuing). TCP traffic was going all over the chart. With nothing controlling the traffic, throughput is horrible and completely unpredictable! With Traffic Shaping, Frame Relay DE bit setting, Class-Based Weighted Fair Queuing (CBWFQ), and Weighted Random Early Detection (WRED) enabled, the network is much more well behaved. We’ll discuss CBWFQ and WRED in the Queuing module. In this section we’ll look at techniques for Classification and Marking. These are the beginning of solving the example customer’s problem. Classification and Marking do not in themselves solve the customer problem. They do however allow us to apply queuing and shaping techniques, both in the edge router doing the classification and marking, and in the downstream routers in the network. Classification and Marking will be further defined in the following slides. Terminology: CIR Committed Information Rate Copyright © 2000, Cisco Systems, Inc. 7 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Internet Classification and marking of packets at the edge of the network makes the packets accessible to QoS handling within the network Classification and marking of packets at the edge of the network makes the packets accessible to QoS handling within the network Network Management Classifying and Marking Classifying and Marking In order for QoS methods to be used within the network, traffic must be classified into higher and lower priorities. Each classification must then be marked so the network knows which QoS methods to apply. This process is completed at the ingress points to the network. Queuing and shaping methods can then be applied throughout the network. The Classification and Marking work is usually done at the edge of the network where speeds are lower. This is because it can be more CPU and memory intense. In general, at the edge we can use relatively complex access lists, flows, and other techniques to recognize traffic. In the network core, where speeds are higher, we keep things simpler, by using marked packets (simpler lookups) and Classes of Service (several major categories of traffics rather than per-application or per-flow handling). Copyright © 2000, Cisco Systems, Inc. 8 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Classification What Is it? Classification What Is it? Classification is . • The QoS feature component that recognizes and distinguishes among different packet streams • The most fundamental QoS building block Without classification, all packets will be treated the same Classification entails using a traffic descriptor to categorize a packet within a specific group to define that packet and make it accessible for QoS handling on the network. Using packet classification, you can partition network traffic into multiple priority levels or classes of service. When traffic descriptors are used to classify traffic, the source agrees to adhere to the contracted terms and the network promises a quality of service. Traffic policers, such as Committed Access Rate's (CARs) rate-limiting feature, and traffic shapers, such as Frame Relay Traffic Shaping (FRTS) and Generic Traffic Shaping (GTS), use a packet's traffic descriptor—that is, its classification—to ensure adherence to the contract. Packet classification is pivotal to policy techniques that select packets traversing a network element or a particular interface for different types ofQoS service. For example, you can use classification to mark certain packets for IP Precedence and you can identify others as belonging to a Resource Reservation Protocol (RSVP) flow. Methods of classification were once limited to use of the contents of the packet header. Today's methods of marking a packet with its classification allow you to set information in the Layer 2, 3, or 4 headers, or even to set information within the packet's payload. Criteria for classification of a group might be as broad as “traffic destined for subnetwork X” or as narrow as a single flow. Copyright © 2000, Cisco Systems, Inc. 9 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Marking What is it? Marking What is it? Marking is… • The QoS feature component that “colors” a packet so that it can be identified and distinguished among other packets in QoS treatment: –Differentiated Services Code Point (DSCP) –IP Precedence –QoS-Group –802.1p Packets entering the network may have been marked previously. If this marking is from a trusted source, then classification may be based on the previous mark. If the marking is not from a trusted source, then classification may be used to determine what the new marking should be. Marking can occur at Layer 2 or Layer 3, however many QoS features are based on the IP Precedence bit or DSCP settings. There are methods of marking that will map Layer 2 Class of Service (CoS) bits to Layer 3 IP Precedence or DSCP settings. A QoS-group is internal to a router. It allows us to virtually mark packets as they come into a router, then use that virtual marking for outbound policy. The biggest advantage to virtual marking is that it does not alter the traffic passing through the router. Copyright © 2000, Cisco Systems, Inc. 10 © 2000, Cisco Systems, Inc. www.cisco.com econ_0386_09_010.ppt Keep All Graphics Inside This Box Topics Topics Modular CLI for QoS Classification Marking [...]... class-map command, with one or more QoS policies The result of this association is called a service policy A service policy contains three elements: a name, a traffic class (specified with the class command), and the QoS policies The purpose of the service policy is to associate a traffic class with one or more QoS policies The name of a service policy is specified in the policy-map command-line interface... a service policy named gary) The service- policy command is used to attach the service policy, as specified with the policy-map command, to an interface Because the elements of the service policy can be applied to packets entering and leaving the interface, users are required to specify whether the service policy characteristics should be applied to incoming or outgoing packets For instance, the service- policy... the Cisco IOS software leaves the IP Precedence value untouched, preserving the precedence value set in the header, allowing all internal network devices to provide service based on the IP Precedence setting This policy follows the standard approach stipulating that network traffic should be sorted into various types of service at the basic perimeter of the network and that those types of service should... pt p IP is normally thought of as being a “best effort” only protocol But IP has always had a mechanism for supporting differentiated services The IP Type of Service (ToS) field, and the IP Precedence bits provide this capability Because the majority of applications today are IP-based, why not leverage IP for end-to-end QoS policy signaling? IP Precedence takes advantage of in-band signaling The ToS... header, with 3 IP Precedence bits in the Type of Service (ToS) field The newer Diff-Serv specification (DSCP) uses instead 6 of the ToS bits, plus the other two bits for flow control Although Layer 3 mechanisms provide end-to-end classification, they are not recognized by switches, hence the need for additional Layer 2 mechanisms to provide continuous quality of service into the LAN segments The Layer 2... econ_0386_09_010 pt p A per-hop behavior (PHB) is a description of the externally observable forwarding behavior of a DS node applied to a the set of packets with the same DSCP The PHB may be defined in terms of their resources priority relative to others PHBs or the observable traffic characteristics (delay, loss, …) PHBs are defined in term of behavior characteristics, the standard does NOT mandate particular... precedence bits in the IP header ToS field to specify class of service for each packet You can partition traffic in up to six classes of service using IP Precedence (two others are reserved for internal network use) The queuing technologies throughout the network can then use this signal to provide the appropriate expedited handling IP Precedence enables service classes to be established using existing network... pt p Using MQC, various match criteria may be used to define a class of service This is classification (continued) • match qos-group number: specifies the number of the QoS group index used as a match criterion against which packets are checked to determine if they belong to the class • match protocol protocol: specifies the name of the protocol used as a match criterion against which packets are checked... the source of the HTTP GET request Memory Management: NBAR uses approximately 150 bytes of DRAM for each flow that requires stateful inspection When NBAR is configured, it allocates 1 MB of DRAM to support up to 5000 concurrent flows NBAR determines if it needs more memory to handle additional concurrent stateful flows If such a need is detected, NBAR expands its memory usage in increments of 200 KB... as the Differentiated Services Code Point, DSCP The priority represented by a particular DSCP value is configurable DSCP values range from 0 to 63 The slide shows the breakout of the DSCP field Six bits are used for the Differentiated Service Code Point, and 2 bits are currently unused Layer 3 IP packets can carry either an IP Precedence value or a DSCP value MQC supports the use of either value in set . Cisco Systems, Inc. 1 © 2000, Cisco Systems, Inc. Infrastructure Quality of Service Infrastructure Quality of Service Copyright © 2000, Cisco Systems, Inc architecture Copyright © 2000, Cisco Systems, Inc. 4 Quality of Service Classification and Marking Quality of Service Classification and Marking © 2000, Cisco