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by Peter Lundqvist, Miguel Barreiros
QOS-Enabled Networks, 2nd Edition
Cover
Title Page
About the Authors
Foreword
Preface
History of This Project
Who Should Read This Book?
Structure of the Book
Acknowledgments
Abbreviations
Part I: The QOS Realm
1 The QOS World
1.1 Operation and Signaling
1.2 Standards and Per-Hop Behavior
1.3 Traffic Characterization
1.4 A Router without QOS
1.5 Conclusion
References
Further Reading
2 The QOS Tools
2.1 Classifiers and Classes of Service
2.2 Metering and Coloring—CIR/PIR Model
2.3 The Policer Tool
2.4 The Shaper Function
2.5 Comparing Policing and Shaping
2.6 Queue
2.7 The Scheduler
2.8 The Rewrite Tool
2.9 Example of Combining Tools
2.10 Delay and Jitter Insertion
2.11 Packet Loss
2.12 Conclusion
Reference
3 Challenges
3.1 Defining the Classes of Service
3.2 Classes of Service and Queues Mapping
3.3 Inherent Delay Factors
3.4 Congestion Points
3.5 Trust Borders
3.6 Granularity Levels
3.7 Control Traffic
3.8 Trust, Granularity, and Control Traffic
3.9 Conclusion
Further Reading
4 Special Traffic Types and Networks
4.1 Layer 4 Transport Protocols: UDP and TCP
4.2 Data Center
4.3 Real-Time Traffic
Reference
Further Reading
Part II: Tools
5 Classifiers
5.1 Packet QOS Markings
5.2 Inbound Interface Information
5.3 Deep Packet Inspection
5.4 Selecting Classifiers
5.5 The QOS Network Perspective
5.6 MPLS DiffServ-TE
5.7 Mixing Different QOS Realms
5.8 Conclusion
References
6 Policing and Shaping
6.1 Token Buckets
6.2 Traffic Bursts
6.3 Dual-Rate Token Buckets
6.4 Shapers and Leaky Buckets
6.5 Excess Traffic and Oversubscription
6.6 Comparing and Applying Policer and Shaper Tools
6.7 Conclusion
Reference
7 Queuing and Scheduling
7.1 Queuing and Scheduling Concepts
7.2 Packets and Cellification
7.3 Different Types of Queuing Disciplines
7.4 FIFO
7.5 FQ
7.6 PQ
7.7 WFQ
7.8 WRR
7.9 DWRR
7.10 PB-DWRR
7.11 Conclusions about the Best Queuing Discipline
Further Reading
8 Advanced Queuing Topics
8.1 Hierarchical Scheduling
8.2 Queue Lengths and Buffer Size
8.3 Dynamically Sized versus Fixed-Size Queue Buffers
8.4 RED
8.5 Using RED with TCP Sessions
8.6 Differentiating Traffic inside a Queue with WRED
8.7 Head versus Tail RED
8.8 Segmented and Interpolated RED Profiles
8.9 Conclusion
Reference
Further Reading
Part III: Case Studies
9 The VPLS Case Study
9.1 High-Level Case Study Overview
9.2 Virtual Private Networks
9.3 Service Overview
9.4 Service Technical Implementation
9.5 Network Internals
9.6 Classes of Service and Queue Mapping
9.7 Classification and Trust Borders
9.8 Admission Control
9.9 Rewrite Rules
9.10 Absorbing Traffic Bursts at the Egress
9.11 Queues and Scheduling at Core-Facing Interfaces
9.12 Queues and Scheduling at Customer-Facing Interfaces
9.13 Tracing a Packet through the Network
9.14 Adding More Services
9.15 Multicast Traffic
9.16 Using Bandwidth Reservations
9.17 Conclusion
Further Reading
10 Case Study QOS in the Data Center
10.1 The New Traffic Model for Modern Data Centers
10.2 The Industry Consensus about Data Center Design
10.3 What Causes Congestion in the Data Center?
10.4 Conclusions
Further Reading
11 Case Study IP RAN and Mobile Backhaul QOS
11.1 Evolution from 2G to 4G
11.2 2G Network Components
11.3 Traffic on 2G Networks
11.4 3G Network Components
11.5 Traffic on 3G Networks
11.6 LTE Network Components
11.7 LTE Traffic Types
11.8 LTE Traffic Classes
11.9 Conclusion
References
Further Reading
12 Conclusion
Index
End User License Agreement
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QOS-ENABLED NETWORKS
Table of Contents
Cover
Title Page
About the Authors
Foreword
Preface
History of This Project
Who Should Read This Book?
Structure of the Book
Acknowledgments
Abbreviations
Part I: The QOS Realm
1 The QOS World
1.1 Operation and Signaling
1.2 Standards and Per-Hop Behavior
1.3 Traffic Characterization
1.4 A Router without QOS
1.5 Conclusion
References
Further Reading
2 The QOS Tools
2.1 Classifiers and Classes of Service
2.2 Metering and Coloring—CIR/PIR Model
2.3 The Policer Tool
2.4 The Shaper Function
2.5 Comparing Policing and Shaping
2.6 Queue
2.7 The Scheduler
2.8 The Rewrite Tool
2.9 Example of Combining Tools
2.10 Delay and Jitter Insertion
2.11 Packet Loss
2.12 Conclusion
Reference
3 Challenges
3.1 Defining the Classes of Service
3.2 Classes of Service and Queues Mapping
3.3 Inherent Delay Factors
3.4 Congestion Points
3.5 Trust Borders
3.6 Granularity Levels
3.7 Control Traffic
3.8 Trust, Granularity, and Control Traffic
3.9 Conclusion
Further Reading
4 Special Traffic Types and Networks
4.1 Layer 4 Transport Protocols: UDP and TCP
4.2 Data Center
4.3 Real-Time Traffic
Reference
Further Reading
Part II: Tools
5 Classifiers
5.1 Packet QOS Markings
5.2 Inbound Interface Information
5.3 Deep Packet Inspection
5.4 Selecting Classifiers
5.5 The QOS Network Perspective
5.6 MPLS DiffServ-TE
5.7 Mixing Different QOS Realms
5.8 Conclusion
References
6 Policing and Shaping
6.1 Token Buckets
6.2 Traffic Bursts
6.3 Dual-Rate Token Buckets
6.4 Shapers and Leaky Buckets
6.5 Excess Traffic and Oversubscription
6.6 Comparing and Applying Policer and Shaper Tools
6.7 Conclusion
Reference
7 Queuing and Scheduling
7.1 Queuing and Scheduling Concepts
7.2 Packets and Cellification
7.3 Different Types of Queuing Disciplines
7.4 FIFO
7.5 FQ
7.6 PQ
7.7 WFQ
7.8 WRR
7.9 DWRR
7.10 PB-DWRR
7.11 Conclusions about the Best Queuing Discipline
Further Reading
8 Advanced Queuing Topics
8.1 Hierarchical Scheduling
8.2 Queue Lengths and Buffer Size
8.3 Dynamically Sized versus Fixed-Size Queue Buffers
8.4 RED
8.5 Using RED with TCP Sessions
8.6 Differentiating Traffic inside a Queue with WRED
8.7 Head versus Tail RED
8.8 Segmented and Interpolated RED Profiles
8.9 Conclusion
Reference
Further Reading
Part III: Case Studies
9 The VPLS Case Study
9.1 High-Level Case Study Overview
9.2 Virtual Private Networks
9.3 Service Overview
9.4 Service Technical Implementation
9.5 Network Internals
9.6 Classes of Service and Queue Mapping
9.7 Classification and Trust Borders
9.8 Admission Control
9.9 Rewrite Rules
9.10 Absorbing Traffic Bursts at the Egress
9.11 Queues and Scheduling at Core-Facing Interfaces
9.12 Queues and Scheduling at Customer-Facing Interfaces
9.13 Tracing a Packet through the Network
9.14 Adding More Services
9.15 Multicast Traffic
9.16 Using Bandwidth Reservations
9.17 Conclusion
Further Reading
10 Case Study QOS in the Data Center
10.1 The New Traffic Model for Modern Data Centers
10.2 The Industry Consensus about Data Center Design
10.3 What Causes Congestion in the Data Center?
10.4 Conclusions
Further Reading
11 Case Study IP RAN and Mobile Backhaul QOS
11.1 Evolution from 2G to 4G
11.2 2G Network Components
11.3 Traffic on 2G Networks
11.4 3G Network Components
11.5 Traffic on 3G Networks
11.6 LTE Network Components
11.7 LTE Traffic Types
11.8 LTE Traffic Classes
11.9 Conclusion
References
Further Reading
12 Conclusion
Index
End User License Agreement
List of Tables
Chapter 02
Table 2.1 PHB requirements
Chapter 05
Table 5.1 Classification rules in the IP realms A and B with four classes of service
Table 5.2 Classification rules in the MPLS realm
Table 5.3 Classification rules in the IP realms A and B with 10 classes of service
Table 5.4 Classification rules using the EXP field and interface
Chapter 06
Table 6.1 Differences between policing and shaping
Chapter 09
Table 9.1 Classes of service requirements
Table 9.2 Classes of service-to-queue mapping
Table 9.3 Classification rules
List of Illustrations
Chapter 01
Figure 1.1 End-to-end consistency
Figure 1.2 Signaling information between neighbors
Figure 1.3 MPLS-TE bandwidth reservations
Figure 1.4 Delay, jitter, and packet loss across the network
Figure 1.5 Jitter reduction by using a buffer at the destination application
Figure 1.6 Traffic flow across a router without QOS
Figure 1.7 Router with QOS enables packet prioritization
Chapter 02
Figure 2.1 The classifier operation
Figure 2.2 The CIR/PIR model
Figure 2.3 The metering tool
Figure 2.4 The policer tool
Figure 2.5 Combining the policer and the metering tools
Figure 2.6 The shaper tool
Figure 2.7 Comparing the policer and the shaper tools
Figure 2.8 The queue operation
Figure 2.9 The scheduler operation
Figure 2.10 The rewrite operation
Figure 2.11 Information propagation
Figure 2.12 Rewrite tool applicability
Figure 2.13 Traffic flow across the router
Figure 2.14 Tools combination scenario
Figure 2.15 Adding a downstream neighbor
Figure 2.16 Bidirectional traffic
Figure 2.17 Two queues and a round-robin scheduler
Figure 2.18 Packet X standing at the queue B head
Figure 2.19 Worst-case delay scenario with a full queue
Figure 2.20 Two equal queues
Figure 2.21 Uneven scheduler operation
Figure 2.22 Best-case and worst-case scenarios in terms of jitter insertion
Figure 2.23 Jitter insertion due to scheduler jumps
Figure 2.24 Traffic dropped due to the lack of queuing resources
Chapter 03
Figure 3.1 Prioritizing one class of service
Figure 3.2 Mapping between services and classes of service
Figure 3.3 Each queue associated with the scheduling policy provides a specific behavior
Figure 3.4 Green and yellow traffic in the same queue
Figure 3.5 Different dropper behaviors applied to green and yellow traffic
Figure 3.6 Using a different queue for yellow traffic
Figure 3.7 Maximum number of queues and maximum length
Figure 3.8 Delay incurred at each hop
Figure 3.9 One queue with 1500-byte and 64-byte packets
Figure 3.10 Link fragmentation and interleaving operation
Figure 3.11 Multiple possible paths with different delay values
Figure 3.12 Queuing and scheduling delay as the only variable
Figure 3.13 Using MPLS-TE to control which traffic is subject to which delay
Figure 3.14 Congestion point because the traffic rate is higher than the physical interface bandwidth. P, physical interface bandwidth
Figure 3.15 Congestion point artificially created. C, contracted bandwidth; P, physical interface bandwidth
Figure 3.16 Congestion point in a hub-and-spoke topology
Figure 3.17 Congestion point due to a failure scenario
Figure 3.18 The border between trust zones
Figure 3.19 Customer- and core-facing interfaces
Figure 3.20 Control traffic in the network
Figure 3.21 Traffic flow across two network routers
Figure 3.22 Queuing on a core-facing interface
Chapter 04
Figure 4.1 Proactive packet drop
Figure 4.2 TCP segmentation
Figure 4.3 TCP acknowledge of segments
Figure 4.4 TCP duplicate ACK
Figure 4.5 The TCP three-way handshake process
Figure 4.6 Double push
Figure 4.7 Big TCP push
Figure 4.8 TCP throughput and congestion avoidance
Figure 4.9 Retransmission delay
Figure 4.10 PAUSE frames
Figure 4.11 PAUSE frames per QOS marking
Figure 4.12 Priority Flow Control
Figure 4.13 West–East traffic flows in a Data Center
Figure 4.14 The RTP data packets and RCTP control packet rates
Figure 4.15 SIP register process, the classical 200 OK messages
Chapter 05
Figure 5.1 TOS field in IPv4 packets
Figure 5.2 Classification based on the packets’ QOS markings and input interface
Figure 5.3 Classification occurs at each hop
Figure 5.4 Possible values of the IP Precedence field
Figure 5.5 Classifier granularity and limit to the number of classes of service
Figure 5.6 One EXP marking per class of service
Figure 5.7 Two EXP markings per class of service
Figure 5.8 Classification in the MPLS DiffServ-TE realm
Figure 5.9 Connecting two IP networks via MPLS
Figure 5.10 Packet traversing different realms
Figure 5.11 Exhaustion of the MPLS classifiers’ granularity
Figure 5.12 Mapping traffic to different tunnels according to the QOS marking
Figure 5.13 MPLS classifiers based on the EXP and tunnel from which traffic is received
Chapter 06
Figure 6.1 High-level view of the policing operation
Figure 6.2 Token bucket structure
Figure 6.3 Two packets arriving at the token bucket
Figure 6.4 Packet discarded by the token bucket
Figure 6.5 Packet transmitted by the token bucket
Figure 6.6 Starting point for a token bucket with credit refill
Figure 6.7 Packet 1 is transmitted
Figure 6.8 Packet 2 is discarded
Figure 6.9 Traffic burst
Figure 6.10 Ingress policer and output queue
Figure 6.11 Different types of traffic with different policing requirements
Figure 6.12 Interconnection between the credit rates of two token buckets
Figure 6.13 Leaky bucket operation
Figure 6.14 Oversubscription scenario. P, physical interface bandwidth; L, logical interface bandwidth
Figure 6.15 Scenario for policing and shaping applicability
Chapter 07
Figure 7.1 Queuing and scheduling applying different behaviors
Figure 7.2 Bandwidth parameter in queuing and scheduling. I, interface bandwidth; S, shaping rate
Figure 7.3 Tail and head aging drops in a queue
Figure 7.4 Cellification of a packet
Figure 7.5 FIFO scheduling
Figure 7.6 Fairness algorithm
Figure 7.7 PQ scheduling
Figure 7.8 WFQ scheduling
Figure 7.9 WRR scheduling
Figure 7.10 Comparing WRR with large and small packets
Figure 7.11 DWRR scheduling configuration
Figure 7.12 DWRR scheduling, turn 1, Q0
Figure 7.13 DWRR scheduling, turn 1, Q1
Figure 7.14 DWRR scheduling, turn 1, Q2
Figure 7.15 DWRR scheduling, turn 2, Q0
Figure 7.16 DWRR scheduling, turn 2, Q1
Figure 7.17 DWRR scheduling, turn 2, Q2
Figure 7.18 DWRR scheduling, turn 3, Q1
Figure 7.19 DWRR scheduling, turn 3, leftover bandwidth
Figure 7.20 DWRR scheduling, turn 1, Q2 with negative credits
Figure 7.21 PB-DWRR scheduling, with one strict-high priority queue
Figure 7.22 PB-DWRR scheduling, policed priority-high queue
Figure 7.23 PB-DWRR scheduling with two priority-high queues
Figure 7.24 PB-DWRR scheduling, turn 1, Q2 and Q3
Figure 7.25 PB-DWRR scheduling, turn 2, Q2 and Q3
Figure 7.26 PB-DWRR scheduling, turn 2, Q0 and Q1
Chapter 08
Figure 8.1 Aggregated hierarchical rate provisioning model
Figure 8.2 Hierarchical scheduling model
Figure 8.3 Propagation of priority queues
Figure 8.4 The PIR/CIR model
Figure 8.5 Every router stands on its own regarding QOS
Figure 8.6 End-to-end QOS policy for certain traffic classes
Figure 8.7 Dynamic buffer allocation example
Figure 8.8 Tail-drop behavior
Figure 8.9 RED drops
Figure 8.10 TCP congestion mechanism
Figure 8.11 Multiple RED drop levels in the same queue
Figure 8.12 Aggressive RED drop levels for out-of-contract traffic
Figure 8.13 Head-based RED
Figure 8.14 Tail-based RED
Figure 8.15 Bad news should travel fast
Figure 8.16 Interpolated and segmented RED profiles
Figure 8.17 Interpolated RED drop curve example 1
Figure 8.18 Interpolated RED drop curve example 2
Chapter 09
Figure 9.1 MPLS tunnels used to forward the customer traffic
Figure 9.2 Customer traffic
Figure 9.3 Delay assurance across a service provider network
Figure 9.4 Hub-and-spoke VLAN
Figure 9.5 DSL scenario for the hub-and-spoke VLAN
Figure 9.6 Packet forwarding inside the hub-and-spoke VLAN
Figure 9.7 VPLS mesh groups
Figure 9.8 Network internal routing with MPLS-TE ERO
Figure 9.9 Classification at customer-facing interfaces
Figure 9.10 Classification at core-facing interfaces
Figure 9.11 Applicability of EXP rewrite rules
Figure 9.12 Customer traffic with QOS markings outside the specified range
Figure 9.13 Bleaching the QOS markings of customer traffic
Figure 9.14 Hierarchical shaper
Figure 9.15 Interface bandwidth and buffer division across the classes of service
Figure 9.16 Queuing and scheduling at core-facing interfaces
Figure 9.17 Tracing a packet across the network
Figure 9.18 Packet walkthrough across the ingress PE router
Figure 9.19 Packet walkthrough across the P router
Figure 9.20 WRED operation
Figure 9.21 Packet passage through the egress PE router
Figure 9.22 Adding a new L3VPN service
Figure 9.23 Delivery of multicast traffic using P2MP LSPs
Figure 9.24 Using LSPs with bandwidth reservations and ERO
Chapter 10
Figure 10.1 North–South versus East–West traffic
Figure 10.2 North–South traffic model
Figure 10.3 East–West traffic model
Figure 10.4 Applications run where resources are available
Figure 10.5 Data replication
Figure 10.6 ECMP mesh
Figure 10.7 Functions and compute on the Leaf only
Figure 10.8 Leaf switch oversubscription by design
Figure 10.9 Speed conversion
Figure 10.10 Bit rate difference needs buffering
Figure 10.11 Serialization difference interface speed 100 byte
Figure 10.12 Bit rate consistency
Figure 10.13 TCP Incast
Chapter 11
Figure 11.1 Key elements of a GSM network
Figure 11.2 Transport elements of the 2G network
Figure 11.3 3G GPRS architecture
Figure 11.4 3G radio interface
Figure 11.5 GTP tunneling
Figure 11.6 The GTP header
Figure 11.7 PDP context activation flow
Figure 11.8 GTP QOS vs. IP QOS
Figure 11.9 LTE architecture
Figure 11.10 Encapsulations of LTE packets sent between NodeB and S-GW
Figure 11.11 Bearer services
Figure 11.12 UMTS traffic classes in TS 23.107
Figure 11.13 LTE traffic classes in TS 23.203 [4]
Figure 11.14 Example of mapping traffic classes between the IETF and 3GPP
Figure 11.15 Example of traffic class mapping IETF<->3GPP
Figure 11.16 Classification and rewriting on the eNodeB
Guide
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