End-to-end QoS deployment techniques for Cisco Catalyst series switches
Examine various QoS components, including congestion management, congestion
avoidance, shaping, policing/admission control, signaling, link efficiency mechanisms, and classification and marking
Map specified class of service (CoS) values to various queues and maintain CoS values through the use of 802.1q tagging on the Cisco Catalyst 2900XL, 3500XL and Catalyst 4000 and 2948G/2980G CatOS Family of Switches
Learn about classification and rewrite capabilities and queue scheduling on the Cisco Catalyst 5000
Implement ACLs, ACPs, ACEs, and low-latency queuing on the Cisco Catalyst 2950 and 3550 Family of Switches
Understand classification, policying, and scheduling capabilities of the Catalyst 4000 and 4500 IOS Family of Switches
Configure QoS in both Hybrid and Native mode on the Catalyst 6500 Family of Switches Utilize Layer 3 QoS to classify varying levels of service with the Catalyst 6500 MSFC and Flexwan
Understand how to apply QoS in campus network designs by examining end-to-end case studies
Quality of service (QoS) is the set of techniques designed to manage network resources. QoS refers to the capability of a network to provide better service to selected network traffic over various LAN and WAN technologies. The primary goal of QoS is to provide flow priority, including dedicated bandwidth, controlled jitter and latency (required by some interactive and delay-sensitive traffic), and improved loss characteristics.
While QoS has become an essential technology for those organizations rolling out a new routers provide EF or AF treatment to implement these RFCs. Later chapters detail the
implementation specifics on the various Catalyst platforms, but it's important to first understand these RFCs as they are implemented on Cisco routers so that you can use the Catalyst
information provided later to develop an end-to-end QoS strategy for your network.
EF Treatment
First, the EF PHB recommends DSCP 46 (101110) be used to mark packets that should received EF treatment. The mechanism for performing this marking is beyond the scope of RFC 2598, but many mechanisms can be used to perform this task, as the list that follows demonstrates:
CAR
Policy-based routing Dial peers
Class-based marking Class-based policer
In almost every case, class-based marking and class-based policer are the recommended methods for performing packet marking in Cisco routers.
The mechanism in Cisco routers that actually provides the EF treatment to packets is called Low Latency Queuing (LLQ). A lengthy discussion of LLQ's operation is beyond the scope of this text, but the basic configuration defines a rate of departure for packets classified into the LLQ for EF treatment. This definition of the rate of departure activates a policer for the rate of arrival for packets into the LLQ. As such, a definition of 128 kbps of bandwidth with LLQ treatment means that, if 129 kbps of traffic is marked for EF, and offered to the LLQ, 1 kbps will be dropped. LLQ extends the CBWFQ model by introducing a single, strict priority queue.
AF Treatment
With regard to the same packet marking tools previously discussed, 12 codepoints are
recommended for use with AF. These 12 codepoints, listed earlier in the chapter, are divided into 4 classes, each with 3 codepoints.
Figure 1-8 shows a possible implementation of AF.
Figure 1-8. Possible Implementation of Assured Forwarding
• Table of Contents
• Index
Cisco Catalyst QoS: Quality of Service in Campus Networks By Mike Flannagan CCIE® No. 7651, Richard Froom CCIE No. 5102, Kevin Turek CCIE No. 7284
Publisher: Cisco Press Pub Date: June 06, 2003
ISBN: 1-58705-120-6 Pages: 432
End-to-end QoS deployment techniques for Cisco Catalyst series switches
Examine various QoS components, including congestion management, congestion
avoidance, shaping, policing/admission control, signaling, link efficiency mechanisms, and classification and marking
Map specified class of service (CoS) values to various queues and maintain CoS values through the use of 802.1q tagging on the Cisco Catalyst 2900XL, 3500XL and Catalyst 4000 and 2948G/2980G CatOS Family of Switches
Learn about classification and rewrite capabilities and queue scheduling on the Cisco Catalyst 5000
Implement ACLs, ACPs, ACEs, and low-latency queuing on the Cisco Catalyst 2950 and 3550 Family of Switches
Understand classification, policying, and scheduling capabilities of the Catalyst 4000 and 4500 IOS Family of Switches
Configure QoS in both Hybrid and Native mode on the Catalyst 6500 Family of Switches Utilize Layer 3 QoS to classify varying levels of service with the Catalyst 6500 MSFC and Flexwan
Understand how to apply QoS in campus network designs by examining end-to-end case studies
Quality of service (QoS) is the set of techniques designed to manage network resources. QoS refers to the capability of a network to provide better service to selected network traffic over various LAN and WAN technologies. The primary goal of QoS is to provide flow priority, including dedicated bandwidth, controlled jitter and latency (required by some interactive and delay-sensitive traffic), and improved loss characteristics.
While QoS has become an essential technology for those organizations rolling out a new In this example
A class called Customer-A will get AF11, AF12, and AF13 traffic.
A class called Customer-B will get AF21, AF22, and AF23 traffic.
A class called Customer-C will get AF31, AF32, and AF33 traffic.
A class called Customer-D will get AF41, AF42, and AF43 traffic.
For each customer, an ingress policer marks the traffic based on the rate of the traffic. Up to 256 kbps is marked AFx1, above 256 kbps but below 768 kbps is marked AFx2, and above 768 kbps is marked AFx3. During periods of congestion, this traffic is placed into the classes described earlier as it egresses the aggregation router toward other regions. Because each class of traffic is independently forwarded, and each class is guaranteed a certain amount of bandwidth (using CBWFQ), the classes do not interfere with each other in any way.
Assume congestion and that Customers A, B, and C are all sending traffic at their CIR, but Customer D is sending traffic at 1.5 Mbps. It wouldn't be fair to punish the other customers because Customer D is not "behaving," so traffic is queued in the class called Customer-D and, when that queue begins to fill, WRED begins to discard packets. Per the RFC that defines AF, packets marked AF43 (those that were over 768 kbps) are discarded first, then packets marked AF42 (those that were between 256 kbps and 768 kbps), and packets marked AF41 are
discarded only if no packets are marked AF43 or AF42.
It's not difficult to see how this could provide a service similar to Frame Relay where there is a CIR with burst and extended burst capabilities. However, no hard rule mandates the purpose for which AF must be used in your network.
• Table of Contents
• Index
Cisco Catalyst QoS: Quality of Service in Campus Networks By Mike Flannagan CCIE® No. 7651, Richard Froom CCIE No. 5102, Kevin Turek CCIE No. 7284
Publisher: Cisco Press Pub Date: June 06, 2003
ISBN: 1-58705-120-6 Pages: 432
End-to-end QoS deployment techniques for Cisco Catalyst series switches
Examine various QoS components, including congestion management, congestion
avoidance, shaping, policing/admission control, signaling, link efficiency mechanisms, and classification and marking
Map specified class of service (CoS) values to various queues and maintain CoS values through the use of 802.1q tagging on the Cisco Catalyst 2900XL, 3500XL and Catalyst 4000 and 2948G/2980G CatOS Family of Switches
Learn about classification and rewrite capabilities and queue scheduling on the Cisco Catalyst 5000
Implement ACLs, ACPs, ACEs, and low-latency queuing on the Cisco Catalyst 2950 and 3550 Family of Switches
Understand classification, policying, and scheduling capabilities of the Catalyst 4000 and 4500 IOS Family of Switches
Configure QoS in both Hybrid and Native mode on the Catalyst 6500 Family of Switches Utilize Layer 3 QoS to classify varying levels of service with the Catalyst 6500 MSFC and Flexwan
Understand how to apply QoS in campus network designs by examining end-to-end case studies
Quality of service (QoS) is the set of techniques designed to manage network resources. QoS refers to the capability of a network to provide better service to selected network traffic over various LAN and WAN technologies. The primary goal of QoS is to provide flow priority, including dedicated bandwidth, controlled jitter and latency (required by some interactive and delay-sensitive traffic), and improved loss characteristics.
While QoS has become an essential technology for those organizations rolling out a new
Summary
This chapter defined QoS as the ability to create predictable service levels for various traffic types in the network, and also as "managed unfairness" (that is, the ability to provide different traffic types with unequal treatment while giving each type the treatment that it requires).
Integrated services and differentiated services have been discussed in detail, and you should now understand where you might find each of these useful in your network. The thorough discussion of some of the key DiffServ RFCs has provided the background information that you need in future chapters, which discuss Cisco's specific implementations of these standards. As these mechanisms are discussed, you should be able to relate their behavior to the standardized behaviors explained by the various RFCs that have been discussed in this chapter.
• Table of Contents
• Index
Cisco Catalyst QoS: Quality of Service in Campus Networks By Mike Flannagan CCIE® No. 7651, Richard Froom CCIE No. 5102, Kevin Turek CCIE No. 7284
Publisher: Cisco Press Pub Date: June 06, 2003
ISBN: 1-58705-120-6 Pages: 432
End-to-end QoS deployment techniques for Cisco Catalyst series switches
Examine various QoS components, including congestion management, congestion
avoidance, shaping, policing/admission control, signaling, link efficiency mechanisms, and classification and marking
Map specified class of service (CoS) values to various queues and maintain CoS values through the use of 802.1q tagging on the Cisco Catalyst 2900XL, 3500XL and Catalyst 4000 and 2948G/2980G CatOS Family of Switches
Learn about classification and rewrite capabilities and queue scheduling on the Cisco Catalyst 5000
Implement ACLs, ACPs, ACEs, and low-latency queuing on the Cisco Catalyst 2950 and 3550 Family of Switches
Understand classification, policying, and scheduling capabilities of the Catalyst 4000 and 4500 IOS Family of Switches
Configure QoS in both Hybrid and Native mode on the Catalyst 6500 Family of Switches Utilize Layer 3 QoS to classify varying levels of service with the Catalyst 6500 MSFC and Flexwan
Understand how to apply QoS in campus network designs by examining end-to-end case studies
Quality of service (QoS) is the set of techniques designed to manage network resources. QoS refers to the capability of a network to provide better service to selected network traffic over various LAN and WAN technologies. The primary goal of QoS is to provide flow priority, including dedicated bandwidth, controlled jitter and latency (required by some interactive and delay-sensitive traffic), and improved loss characteristics.
While QoS has become an essential technology for those organizations rolling out a new
Chapter 2. End-to-End QoS: Quality of Service at Layer 3 and Layer 2
Chapter 1, "Quality of Service: An Overview," introduced several of the fundamental concepts of quality of service (QoS), various key RFCs, and explained various parts of the differentiated services (DiffServ) architecture. This chapter builds upon Chapter 1 by continuing to explore some DiffServ components and looking at mechanisms for traffic conditioning, link efficiency, and classification at Layer 3. This chapter also introduces the concept of Layer 2 packet marking for QoS and explains how Layer 2 markings relate to Layer 3 markings to facilitate end-to-end QoS. Although this chapter doesn't focus specifically on QoS for IP telephony applications, you will find examples of how Layer 2 QoS is used to allow voice traffic to traverse a switched
infrastructure with limited delay and jitter. This chapter also looks at various traffic-conditioning components of QoS.
This chapter primarily focuses on QoS from a Cisco IOS router perspective. In addition, all the examples of this chapter were demonstrated on a Cisco IOS router. The last two sections of this chapter introduce QoS on the Catalyst platforms.
• Table of Contents
• Index
Cisco Catalyst QoS: Quality of Service in Campus Networks By Mike Flannagan CCIE® No. 7651, Richard Froom CCIE No. 5102, Kevin Turek CCIE No. 7284
Publisher: Cisco Press Pub Date: June 06, 2003
ISBN: 1-58705-120-6 Pages: 432
End-to-end QoS deployment techniques for Cisco Catalyst series switches
Examine various QoS components, including congestion management, congestion
avoidance, shaping, policing/admission control, signaling, link efficiency mechanisms, and classification and marking
Map specified class of service (CoS) values to various queues and maintain CoS values through the use of 802.1q tagging on the Cisco Catalyst 2900XL, 3500XL and Catalyst 4000 and 2948G/2980G CatOS Family of Switches
Learn about classification and rewrite capabilities and queue scheduling on the Cisco Catalyst 5000
Implement ACLs, ACPs, ACEs, and low-latency queuing on the Cisco Catalyst 2950 and 3550 Family of Switches
Understand classification, policying, and scheduling capabilities of the Catalyst 4000 and 4500 IOS Family of Switches
Configure QoS in both Hybrid and Native mode on the Catalyst 6500 Family of Switches Utilize Layer 3 QoS to classify varying levels of service with the Catalyst 6500 MSFC and Flexwan
Understand how to apply QoS in campus network designs by examining end-to-end case studies
Quality of service (QoS) is the set of techniques designed to manage network resources. QoS refers to the capability of a network to provide better service to selected network traffic over various LAN and WAN technologies. The primary goal of QoS is to provide flow priority, including dedicated bandwidth, controlled jitter and latency (required by some interactive and delay-sensitive traffic), and improved loss characteristics.
While QoS has become an essential technology for those organizations rolling out a new