Designing Switch/Routers. Fundamental Concepts and Design Methods

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Cover Half Title Title Page Copyright Page Table of Contents Preface Author Chapter 1: The Era of High-Performance Networks 1.1 Introduction 1.2 Introduction to IP Routing 1.3 Characteristics of Enterprise and Service Provider Networks 1.3.1 Characteristics of Enterprise Networks 1.3.2 Characteristics of Service Provider Networks 1.4 Understanding the Evolution to High-Performance Networks 1.5 Introduction to Multilayer Switching and the Switch/Router 1.5.1 The Switch/Router as Merging the Best of Layer 2 Switching and IP Routing 1.5.2 The Switch/Router as Reducing the Complexity of Three-Tier Networking 1.5.3 Layer 2/Layer 3 Convergence on a Single Platform Review Questions References Chapter 2: Introducing Multilayer Switching and the Switch/Router 2.1 Introduction 2.2 Key Terminology and Definitions 2.3 Routing Metric and Administrative Distance (or Route Preference) 2.4 Evolution of the Switch/Router 2.5 First-Generation Routing Devices 2.6 Second-Generation Routing Devices 2.7 Third-Generation Routing Devices 2.8 Fourth (Current) Generation Routing Devices Review Questions References Chapter 3: OSI and TCP/IP Reference Models 3.1 Introduction 3.2 Development of Network Reference Models 3.3 OSI Reference Model 3.3.1 OSI Physical Layer 3.3.2 OSI Data Link Layer 3.3.3 OSI Network Layer 3.3.4 OSI Transport Layer 3.3.5 OSI Session Layer 3.3.6 OSI Presentation Layer 3.3.7 OSI Application Layer 3.4 TCP/IP Reference Model 3.4.1 TCP/IP Link Layer 3.4.2 TCP/IP Network Layer 3.4.3 TCP/IP Transport Layer 3.4.4 TCP/IP Application Layer Review Questions References Chapter 4: Mapping Network Device Functions to the OSI Reference Model 4.1 Introduction 4.2 Repeater and the OSI Model 4.3 Bridge (or Switch) and the OSI Model 4.3.1 Bridge Logical Reference Model 4.3.2 MAC Relay Entity 4.3.3 Filtering Database (MAC Address Table or Layer 2 Forwarding Table) 4.3.3.1 Contents of the Filtering Database 4.3.3.1.1 Static Filtering Information 4.3.3.1.2 Dynamic Filtering Information 4.3.3.1.3 Filtering Entry Parameters 4.3.3.2 Using a Content Addressable Memory for the Filtering Database 4.3.3.3 Aging Out Dynamic Filtering Entries 4.3.4 Overview of IEEE 802.1D Transparent Bridging Algorithm 4.3.5 Special Focus: Ethernet MAC Address Format 4.3.5.1 Organizational Unique Identifier and NIC-Specific Identifier 4.3.5.2 Individual/Group Address Bit 4.3.5.3 Universally/Locally Administered Address Bit 4.3.6 VLANs – A Mechanism for Limiting Broadcast Traffic 4.4 Router and the OSI Model 4.5 Multilayer Switching and the OSI Model: Integrated Layer 2 Switching and Layer 3 Routing 4.6 Layer 4-7 Switching – Going beyond Multilayer Switching (Layer 2/3) 4.6.1 Benefits of Layer 4+ Switching – Higher Infrastructure Return-on-Investment 4.6.2 Architecture and Configuration of Layer 4+ Switching 4.6.3 Capabilities and Applications of Layer 4+ Switching 4.7 Generic IP Host Architecture 4.7.1 Types of NICs 4.7.2 High-Level NIC Architecture 4.8 Configuring MAC Addresses in Ethernet NICs Review Questions References Chapter 5: Review of Layer 2 and Layer 3 Forwarding 5.1 Introduction 5.2 Deciding When to Use Layer 2 or Layer 3 Forwarding for an Arriving Packet 5.3 Layer 2 Forwarding 5.3.1 Layer 2 Forwarding Basics 5.3.2 Lookup Tables Used in Layer 2 Forwarding Operations 5.4 Internetworking Basics 5.4.1 Bridging (Switching) in Internetworks 5.4.2 Routing in Internetworks 5.4.3 Switching within a Subnet 5.4.4 Routing between Subnets 5.5 Control Plane and Data Plane in the Router or Switch/Router 5.5.1 Control Plane 5.5.1.1 Basic Control Plane Operations 5.5.1.2 Routing Table or Routing Information Base 5.5.1.2.1 Routing Table Structure and Representation of Information 5.5.1.2.2 Routing Information Sources and the Routing Table 5.5.1.2.3 Routing Information Sources and Route Selection 5.5.1.2.4 Understanding Route Resolvability 5.5.1.2.5 Routes in the Routing Table, and Their Interfaces and Intermediate IP Addresses 5.5.1.2.6 Routing Table Maintenance 5.5.1.2.7 Recursive Route Lookup in an IP Routing Table 5.5.1.2.8 Resolving Recursive Routes before Installation in the IP Forwarding Table 5.5.1.3 Forwarding Table or Forwarding Information Base 5.5.2 Data Plane 5.5.2.1 Basic Data Plane Operations 5.5.2.1.1 Adjacency Information 5.5.2.1.1.1 Creating Adjacency Information 5.5.2.1.1.2 Network Types and Adjacency Information 5.5.2.1.1.3 Controlling and Maintaining Adjacency Information 5.5.2.1.2 Implications of Classless Inter-Domain Routing on IP Address Lookups 5.5.2.1.3 Handling Local Packet Delivery during IP Packet Forwarding 5.5.2.1.3.1 Performing Lookups for the Local Router IP Addresses 5.5.2.1.3.2 IP Time-to-Live and Local Delivery 5.5.2.1.4 Benefits of Packet Forwarding via the IP Forwarding Table (or FIB) Rather than the Routing Table (or RIB) 5.5.2.1.4.1 Limitations of Route Cache-Based Forwarding 5.5.2.1.4.2 Characteristics of FIB-Based Forwarding 5.5.2.1.4.3 Generating the FIB from the Routing Table 5.5.2.1.4.4 Special Adjacencies 5.5.2.1.5 Reasons for Dropping Packet in Routing Devices 5.5.2.1.6 Why Data Plane Operations Are Amenable to Hardware Processing that Control Plane Operations 5.5.2.2 Unicast Reverse Path Forwarding 5.5.2.3 Multicast Reverse Path Forwarding 5.5.3 Examining the Benefits of Control Plane and Data Plane Separation 5.5.3.1 Scalability and Distributed Forwarding Architectures 5.5.3.1.1 Facilitates the Design of Distributed Forwarding Architectures 5.5.3.1.2 Scaling the Packet Forwarding Capacity of a Routing Device 5.5.3.2 Control Plane Redundancy and Fault Tolerance 5.5.4 Lookup Tables Used in Layer 3/4 Forwarding Operations, QoS, and Security ACLs 5.6 Special Focus: Control Plane Management Subsystems 5.6.1 Simple Network Management Protocol 5.6.2 Remote Network Monitoring 5.6.3 Device GUIs and MIB Browsers Review Questions References Chapter 6: Packet Forwarding in the Switch/Router: Layer 3 Forwarding Architectures 6.1 Introduction 6.2 Packet Forwarding in the Router or Switch/Router 6.3 Packet Forwarding Architectures 6.3.1 Traditional Centralized CPU-Based Forwarding Architectures: Software-Based Forwarding Using the IP Routing Table 6.3.1.1 Packet Forwarding in the Traditional CPU-Based Forwarding Architectures Using the IP Routing Table 6.3.1.1.1 Understanding Process Switching/Forwarding 6.3.1.1.2 Process Switching/Forwarding Steps 6.3.1.2 Limitations of the Traditional CPU-Based Forwarding Architectures 6.3.1.3 Types of Centralized Forwarding Architectures Using the IP Routing Table 6.3.1.3.1 Centralized Processor or CPU-Based Architectures 6.3.1.3.1.1 Typical Components 6.3.1.3.1.2 Cisco Router Buffers and Queues 6.3.1.3.1.3 Device Drivers 6.3.1.3.1.4 Elements of Execution in Some Cisco Routers 6.3.1.3.1.5 Cisco Router Startup Process: Boot Sequence 6.3.1.3.1.6 General Layer 3 Packet Processing in a Router with Centralized Forwarding 6.3.1.3.1.7 Special Focus: IP Packet Processing in a Cisco Router with Centralized Forwarding (Cisco Process Switching) 6.3.1.3.2 Centralized ASIC-Based Architectures 6.3.2 Forwarding Architectures Using Route Caches 6.3.2.1 Temporal and Spatial Locality of IP Traffic Flows 6.3.2.2 Handling Exception Packets 6.3.2.3 Route Cache Performance 6.3.2.3.1 Limitations of Route Caching in Core Networks 6.3.2.3.2 Double IP Address Lookups 6.3.2.3.3 BGP-Learned Routes and Recursive Lookups 6.3.2.4 Implementing Architectures with Route Caches 6.3.2.4.1 Centralized Processor-Based Architectures with Route Caches 6.3.2.4.2 Architectures with a Single Dedicated and Centralized Processor or ASIC-Based Route Cache Lookup Engine 6.3.2.4.3 Distributed Processor or ASIC-Based Architectures with Route Caches 6.3.2.4.3.1 Example Architecture: Forwarding via the Route Cache in the Cisco 7500 Series Routers with Versatile Interface Processors (VIPs) 6.3.2.5 Route Cache Maintenance and Timers 6.3.2.6 Exact Matching in IP Route Caches 6.3.3 Architectures Using Topology-Based Forwarding Tables 6.3.3.1 Implementing Architectures with Topology-Derived Forwarding Tables 6.3.3.1.1 The FIB and Resolved Routes 6.3.3.1.2 Centralized Processor-Based Architectures with Topology-Derived Forwarding Tables 6.3.3.1.3 Centralized ASIC-Based Architectures with Topology-Derived Forwarding Tables 6.3.3.1.4 Distributed Processor or ASIC-Based Architectures with Topology-Derived Forwarding Tables 6.3.3.1.4.1 Device Scalability 6.3.3.1.4.2 Decoupling the Forwarding Table from the Routing Table 6.3.3.1.4.3 Equal-Cost Multi-Path and Load Balancing 6.3.3.1.4.4 Eliminating Route Cache Churn 6.3.3.1.4.5 Maintaining Layer 2 Adjacency Information 6.3.3.1.4.6 Operations in a Generic Distributed Forwarding Architecture 6.3.3.1.4.7 Route Processor Redundancy 6.3.3.1.5 FIB Consistency Checker 6.3.3.1.5.1 Passive and Active Consistency Checkers 6.3.3.1.5.2 Types of Cisco Consistency Checkers 6.3.3.1.5.3 Consistency Checking Process 6.4 Routing between VLANs 6.4.1 What Is a VLAN? 6.4.2 IEEE 801.1Q 6.4.3 Inter-VLAN Routing 6.4.4 Implementing Inter-VLAN Routing 6.4.4.1 Using an External Router 6.4.4.2 Using a One-Armed Router 6.4.4.3 Using a Switch/Router Review Questions References Chapter 7: Review of Multilayer Switching Methods: Switch/Router Internals 7.1 Introduction 7.2 Multilayer Switching Methods 7.3 Understanding the Front-End Processor Approach with Flow-Based Multilayer Switching 7.3.1 Basic Architecture 7.3.2 Flow-Based Multilayer Switching Packet Processing Steps 7.3.3 Multilayer Switching Using a Route Cache and Access Control Lists 7.3.4 Multilayer Switching Cache Timers 7.3.5 MLS-RP to MLS-SE Communications 7.4 IP Multicast Multilayer Switching 7.4.1 Unicast Multilayer Switching in Cisco Catalyst 5000, 6000, and 6500 Series Switches 7.4.2 Understanding IP Multicast Multilayer Switching 7.4.2.1 IP Multicast Multilayer Switching Network Topology 7.4.2.2 Cisco IP Multicast MLS Components 7.4.2.3 Layer 3 Multicast Multilayer Switching Cache 7.4.2.4 Layer 3-Switched Multicast Packet Rewrite 7.5 The FIB, Fast-Path Forwarding, and Distributed Forwarding Architectures 7.5.1 Benefits of Distributed Forwarding 7.5.2 Distributed Forwarding Architecture 7.5.3 Distributed Forwarding with Integrated Hardware Processing 7.5.4 Benefits of Multilayer Switching with Integrated Hardware Processing Review Questions References Chapter 8: Quality of Service in Switch/Routers 8.1 Introduction 8.2 Network Requirements for Real-Time Traffic Transport 8.2.1 Adequate Bandwidth 8.2.2 Network Elements with Non-blocking and Improved Switching and Forwarding Performance 8.2.3 End-to-End QoS 8.2.4 High Telecom Grade Network Availability 8.2.5 Remark on Network QoS for Real-Time Applications 8.3 Elements of QoS in Switch/Routers 8.4 Traffic Classes 8.4.1 IEEE 802.1p/Q 8.4.2 IETF Type-of-Service 8.4.3 IETF Differentiated Services 8.4.4 Traffic Filtering and Deep Packet Pattern Matching 8.4.5 Real-World Implementations of Classes of Service 8.4.6 Example Applications of Packet Classification at Layer 2 8.5 Traffic Management 8.5.1 Setting the Scenario for Congestion in Internetworks 8.5.2 Output Queue Drops 8.5.3 Buffer Sizing 8.5.4 Packet Discard 8.5.4.1 TCP Slow Start and TCP Window Sizes 8.5.4.2 Random Early Detection 8.5.5 Handling Congestion with Multiple QoS Queues 8.6 Packet Marking and Remarking (Rewriting) 8.6.1 IP Precedence Marking 8.6.2 Differentiated Services Code Point Marking 8.6.3 Class of Service Marking Using IEEE 802.1p 8.6.4 MPLS Traffic Class (or EXP) Marking 8.6.4.1 MPLS QoS Services 8.6.4.2 MPLS Tunneling Modes 8.6.5 Tunnel Header Marking 8.7 The Need for QoS Mechanisms in the Switch/Router 8.7.1 Important QoS Features Review Questions References Chapter 9: Rate Management Mechanisms in Switch/Routers 9.1 Introduction 9.2 Traffic Policing 9.2.1 Metering and Marking with a Policer 9.3 Traffic Shaping 9.3.1 Leaky Bucket Algorithm as a Queue 9.4 Traffic Policing and Traffic Shaping Using the Token Bucket Algorithm 9.5 Traffic Coloring and Marking 9.5.1 Two-Color-Marking Policer 9.5.2 Three-Color-Marking Policer 9.6 Implementing Traffic Policing 9.6.1 Single-Rate Two-Color Marker – The Token Bucket Algorithm 9.6.2 Single-Rate Three-Color Marker 9.6.3 Two-Rate Three-Color Marker 9.6.4 Color-Blind versus Color-Aware Policing 9.7 Congestion Management Using Rate Limiters 9.8 Input and Output Tagging – Packet Reclassification and Rewriting 9.9 Traffic Management and QoS Features in Crossbar Switch Fabrics 9.10 Advanced QoS Features in Switch/routers Review Questions References Index