OSPF Network Design Solutions, 2nd Edition

The comprehensive reference for OSPF network design and deployment

• Understand the full dynamics of OSPF network components, how they interact with one another, and how to configure them
• Increase the efficiency of your OSPF network through a variety of performance tuning techniques
• Apply load balancing to enhance OSPF's capability to adapt to network topology changes
• Ensure seamless communication between OSPF and other Interior Gateway Protocols (IGPs) and OSPF and BGP through redistribution
• Optimize network stability and efficiency with OSPF summarization
• Maximize your ability to properly manage an ever-changing OSPF network landscape through Simple Network Management Protocol (SNMP) and Management Information Bases (MIBs)
• Develop a practiced, tested security plan to protect your OSPF network
• Optimize the efficiency and bandwidth of your OSPF network through the integration of MPLS
• Complete your basic OSPF knowledge gaps with a boiled down summary of the OSPF RFCs

One of the most prevalent Interior Gateway Protocols (IGPs), OSPF is in use in numerous networks across the globe. Open Shortest Path First (OSPF) is also one of the most widely tested protocols if you choose to pursue a networking certification. From a technical perspective, the overwhelming presence of OSPF ensures that you will encounter it at some point in your career. As a result, every networking professional should understand how OSPF operates, how to configure and troubleshoot this important protocol, and most importantly how to design a network that uses OSPF.

OSPF Network Design Solutions, Second Edition provides comprehensive coverage of OSPF network design, deployment, management, and troubleshooting. The book begins in Part I by providing you with a common-sense understanding of the primary building blocks of internetworking, and follows up with a detailed examination of how OSPF fits into the big picture. You will also learn how OSPF neighboring routers communicate with one another via link-state advertisements (LSAs) and how to optimize this communication for network efficiency. Part II begins with a detailed explanation of how to apply the "golden rules of design" to create an optimal OSPF network and follows up with a logical approach to configuring OSPF routers and areas. Part II concludes with hard-to-find information about how to redistribute RIP into OSPF and OSPF into BGP as well as how to make your OSPF network more efficient through summarization. Part III provides you with detailed information about how to keep pace with network growth through tested network management tools and techniques. Furthermore, you will learn how to secure your OSPF network from inside and outside attackers and how to troubleshoot your network should problems arise. Part III concludes with timely information about how to accommodate BGP and MPLS in an OSPF network.

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Table of Contents

I. OSPF FUNDAMENTALS AND COMMUNICATION.

Foundations of Networking. Why Was the OSI Reference Model Needed? Characteristics of the OSI Layers. Understanding the Seven Layers of the OSI Reference Model. Upper Layers. Layer 7—Application. Layer 6—Presentation. Layer 5—Session. Lower Layers. Layer 4—Transport. Layer 3—Network. Layer 2—Data Link. Layer 1—Physical. OSI Reference Model Layers and Information Exchange. Headers, Trailers, and Data. TCP/IP Protocol Suite. TCP/IP Functions. TCP Overview. IP Overview. Types of Network Topologies. Local-Area Networks. Wide-Area Networks. IP Addressing. Class A Addresses. Class B Addresses. Class C Addresses. Class D Addresses. Class E Addresses. How IP Addresses Are Used. Role of IP Addresses. How IP Addresses Are Read. IP Subnet Addressing. Subnet Masking. Subnetting Restrictions. Explaining the Need for VLSM and CIDR. Route Summarization. Classful Routing. Impact of Classful Routing. Classless Routing. VLSMs. VLSM Design Guidelines and Techniques. CIDR. Validating a CIDRized Network. What Do Those Slashes Mean? Important CIDR Terms. IP Classless. CIDR Translation Table. Manually Computing the Value of a CIDR IP Prefix. Case Study: VLSMs. Route Aggregation. Summary.

What Is a Routing Protocol? Basic Routing Protocol Operation. Link-State Versus Distance Vector Routing Protocols. Link-State Routing Protocols. OSPF Characteristics. Integrated Intermediate System-to-Intermediate System. Distance Vector Routing Protocols. Routing Information Protocol Characteristics. Conclusion. Selecting a Routing Protocol. Operational Considerations. Protocols Supported. Routing Hierarchies. IP Address Management. IP Encapsulation Support. Available Resources. Technical Considerations. Fast Convergence. Routing Updates. VLSM and CIDR Support. Load Sharing. Metrics. Scalability. Physical Media Support. Extensibility. Business Considerations. Standards. Multivendor Environments. Proven Technology. SPF Overview. SPF in Operation. SPF Functions. Full and Partial SPF Calculations. Verifying SPF Operation. OSPF Routing Hierarchy. Hierarchical Network Design Techniques. Routing Types Within an OSPF Network. Intra-Area Routing. Inter-Area Routing. External Routes. OSPF Areas. Characteristics of a Standard OSPF Area. Standard Area Design Rules. Area 0: The OSPF Backbone Area. Stub Areas. Not-So-Stubby Areas. OSPF Operational Environment. Types of OSPF Routers. Internal Routers. Area Border Routers. Autonomous System Boundary Routers. Backbone Routers. OSPF Network Types. Router Identification. Neighbors. Adjacencies. Neighbor Versus Adjacent OSPF Routers. Designated Routers. Case Study: Adding a New OSPF Router to a Network. Case Study: Developing the Link-State Database. Case Study: OSPF Network Evolution and Convergence. Configuring Loopback Interfaces. Enabling OSPF. Verifying OSPF Operation. Summary.

Link-State Advertisements. Types of LSAs. Type 1: Router LSAs. Type 2: Network LSAs. Type 3: ABR Summary LSAs. Type 4: ASBR Summary LSAs. Type 5: Autonomous System External LSAs. Type 7: Not-So-Stubby Area LSAs. Type 9: Opaque LSA: Link-Local Scope. Type 10: Opaque LSA: Area-Local Scope. Type 11: Opaque LSA: Autonomous System Scope. LSA Operation Example. Link-State Database Synchronization. Speaking OSPF. Types of OSPF Packets. Hello Process/Protocol. Hello Protocol Operational Variations. Hello Protocol Packet Format. Exchange Process/Protocol. Flooding Process/Protocol. Manipulating LSAs. Understanding LSA Group Pacing. How to Configure LSA Group Pacing. Understanding OSPF Packet Pacing. Blocking LSA Flooding. Ignoring MOSPF LSA Packets. Altering LSA Retransmissions. Altering LSA Transmission Delay. Detailed Neighbor Establishment. Hello Protocol State Changes. Database Exchange State Changes. Case Study: OSPF Initialization. Case Study: Troubleshooting Neighbor Problems. Neighbor Stuck in Init STATE. Neighbor Stuck in Exstart/Exchange State. Whats the Solution? Neighbor Stuck in 2-Way State. Summary.

II. OSPF ROUTING AND NETWORK DESIGN.

OSPF Design Guidelines. OSPF Design Goals. Functionality. Scalability. Adaptability. Manageability. Cost Effectiveness. OSPF Network Design Methodology. Step 1: Analyze the Requirements. OSPF Deployment. Load Balancing with OSPF. OSPF Convergence. Step 2: Develop the Network Topology. Fully Meshed Topology. Hierarchical Topology. OSPF Backbone Design in the Hierarchical Model. Area Design in the Hierarchical Model. Using a Stub Area. Example of an OSPF Network with a Hierarchical Structure. Step 3: Determine the Addressing and Naming Conventions. Public or Private Address Space. Plan Now for OSPF Summarization. Bit Splitting (Borrowing Bits). Map OSPF Addresses for VLSM. Discontiguous Subnets. Naming Schemes. Step 4: Provision the Hardware. Step 5: Deploy Protocol and Cisco IOS Software Features. OSPF Features. Cisco IOS Software Features. Step 6: Implement, Monitor, and Manage the Network. OSPF Network Scalability. OSPF Network Topology. Area Sizing. Determining the Number of Areas per ABR. Determining the Number of Areas per Router. Determining the Number of Neighbors per Router. Selecting the Designated Router. Fully Meshed Versus Partially Meshed Network Topology. Link-State Database Size Considerations. Determining Router Memory Requirements. Router CPU Requirements. Bandwidth Usage. OSPF Security. Area Design Considerations. Area Design Overview. Considering Physical Proximity. Reducing the Area Size if Links Are Unstable . Ensuring Contiguous Areas. Using Tunable OSPF Parameters. Naming an Area. Standard Area Design. Golden Rules of Standard Area Design. Backbone Area Design. Backbone Design Golden Rules. Stub Area Design. Stub Area Design Golden Rules. Stub Area Configuration. Totally Stubby Areas. Not-So-Stubby Areas. NSSA Implementation Considerations. OSPF Virtual Links: Bane or Benefit? Mending a Partitioned Area 0. Ensuring a Connection to Area 0. Golden Rules of Virtual Link Design. Virtual Link Configuration Example. OSPF Design Tools. Altering Neighbor Cost. Configuring a Neighbors Cost on Point-to-Multipoint Broadcast Networks. Configuring an Interface as Point-to-Multipoint Nonbroadcast. Configuring Route Calculation Timers. Suppressing OSPF Updates. Summary. Case Studies. Case Study: Understanding Subinterfaces. Point-to-Point Subinterfaces. Multipoint Subinterfaces. Case Study: Point-to-Multipoint Link Networks. Router Configuration Examples. Case Study Conclusion. Case Study: Designing an OSPF Network. New WAN Requirements. Determining the Frame Relay PVC Architecture. Determining Multiprotocol Support. Determining the Traffic Flow. Determining the Number of Routers. Determining the IP Addressing Scheme. Determining Internet Connectivity. Determining Enterprise Routing Policies. Establishing Security Concerns. Implementing Your Design. IP Addressing. OSPF Area Organization. Specifying the OSPF Network Type. Implementing Authentication. Configuring Link Cost. Tuning OSPF Timers. Strategizing Route Redistribution.

OSPF Routing Concepts. OSPF Cost. ip cost Interface Command. Changing the Reference Bandwidth. Altering OSPF Convergence. Hello Timers. Dead Timers. SPF Timers. Setting the Router ID. Loopback Interfaces. Configuring a Loopback Interface. Routing Loopback Interfaces. Configuring the Designated Router. Route Types. Which Is Better—E1 or E2 Routes? Controlling Inter-Area Traffic. Configuring OSPF. Activating OSPF. network Command. OSPF Router Considerations. ABR Considerations. ASBR Considerations. Backbone Router Considerations. Different Network Types and OSPF. Configuring the Network Type. Broadcast Networks. Nonbroadcast Networks. Point-to-Multipoint Networks. Point-to-Point Networks. Area Configuration. Normal Area Configuration. Stub Area Configuration. Totally Stubby Area Configuration. Not-So-Stubby-Area (NSSA) Configuration. area default-cost Command. Area Range. Tuning OSPF Operation. Altering OSPF Administrative Distance. Load Balancing. Default Routes. Passive Interfaces. On-Demand Circuits. Implementation Considerations. On-Demand Configuration Examples. On-Demand Circuits Summary. Summary. Case Study: Assigning Unique Network Numbers to Each OSPF Area. Case Study: OSPF with Multiple Areas. Case Study: OSPF with Stub and Totally Stubby Areas.

OSPF Redistribution. Administrative Distance and Metrics. Redistribution Golden Rules. Redistribution Configuration. External Routes. Default Routes. default-information originate Command. Assigning Metrics for Redistributed Protocols. Using the redistribute Command to Assign a Metric. Using the default-metric Command to Assign a Metric. Configuration Example 1: Setting the Default Metric for Redistributed Routes. Route Tagging. Mutual Redistribution. Distribute List Concerns. Avoiding Redistribution Loops. Route Maps. Configuration Example 2: RIP and OSPF. Configuring the RIP Network. Adding OSPF to the Center of a RIP Network. Adding OSPF Areas. What If Mutual Redistribution Were Required? Configuration Example 3: Redistributing Connected and Loopback Interfaces. Configuration Example 4: Redistributing OSPF and EIGRP. OSPF and EIGRP Mutual Redistribution. Using Route Maps to Protect Against Routing Loops. Using Route Tagging to Protect Against Routing Loops. Configuration Example 5: Redistributing OSPF and RIP and Tagging Routes. OSPF and RIP Mutual Redistribution. Redistributing into OSPF with Route Tagging. Configuration Example 6: Controlling Redistribution. Altering Link Cost. Altering Routes. Filtering Routes. Distribute Lists and OSPF. Chapter Summary.

Summarization with OSPF. Benefits of Summarization. Summarization Golden Rules. Troubleshooting Summarization. Types of OSPF Summarization. Summarize Area Routes. Summarize External Routes. Summarizations Effect on the Routing Table. Configuration Example 3: Subnetting with Summarization. Alternative Area Summarization Example. Using Private Addressing to Summarize? Configuration Example4: Using VLSM with Summarization. Summary. Final Router Example Configurations.

III. OSPF IMPLEMENTATION, TROUBLESHOOTING, AND MANAGEMENT.

Network Management. Network Management Tools. CiscoView. CiscoWorks. Cisco ConfigMaker. Simple Network Management Protocol. Introduction to SNMP. Network Management System. Agents. Managed Devices. Management Information Base Overview. SNMP Operation. SNMP Operation Definitions. Network Management System Operation. Agent Response to NMS Request. Ciscos MIB Extensions+. Access Lists for SNMP. Multiple Community Strings. OSPF MIBs. Network Security. Assessing the Need for Security. Golden Rules for Designing a Secure Network. Document Your Security Plan. Know Your Enemy. Count the Cost. Identify Your Assumptions. Control and Limit Your Secrets. Remember Human Factors. Know Your Weaknesses. Limit the Scope of Access. Understand Your Environment. Limit Your Trust. Remember Physical Security. Security Is Pervasive. Additional Resources on Network Security. Securing Your OSPF Network. OSPF and Network Devices. Cisco IOS Password Encryption. Network Impact: User Passwords (vty and Enable). Increasing SNMP Security. Network Data Encryption. OSPF Authentication. Benefits of OSPF Neighbor Authentication. When to Deploy OSPF Neighbor Authentication. How OSPF Authentication Works. Configuring OSPF Authentication in an Area. Configuring OSPF Authentication on a Virtual Link. Changing the Virtual Link Password. Restricting Access to Network Devices. Controlling Access to Network Equipment. Terminal Access Controller Access Control System. Nonprivileged Access. Privileged Access. Privilege Level Security. Access Lists to Restrict Access. User Authentication to Restrict Access. Summary. Case Study: IOS Secure Template. Case Study: Router and Firewall Deployment. Defending Against Attacks Directly to Network Devices. Controlling Traffic Flow. Configuring the Firewall Router. Defining Firewall Access Lists. Applying Access Lists to Interfaces. Configuring the Communication Server. Defining the Communication Servers Access Lists. Applying Access Lists to Lines. Spoofing and Inbound Access Lists. Additional Firewall Security Considerations. File Transfer Protocol Port.

The Mechanics of Troubleshooting OSPF. Preparing for Network Failure. Troubleshooting Methodology. Step 1: Clearly Define the Problem. Step 2: Gather Facts. Step 3: Consider Possible Problems. Step 4: Create an Action Plan. Step 5: Implement the Action Plan. Step 6: Gather Results. Step 7: Reiterate the Process. Determining That OSPF Is Operating Properly. Monitoring the Operation of OSPF. Configuring Lookup of DNS Names. System Logging (SYSLOG). Configuring SYSLOG. Logging OSPF Neighbor Changes. OSPF Troubleshooting Commands. show ip ospf Command. show ip ospf process-id Command. show ip ospf interface Command. show ip ospf border-routers Command. show ip ospf database Command. show ip ospf database asbr-summary Command. show ip ospf database database-summary Command. show ip ospf database external Command. show ip ospf database network Command. show ip ospf database router Command. show ip ospf database summary Command. show ip ospf delete Command (Hidden). show ip ospf events Command (Hidden). show ip ospf flood-list Command. show ip ospf maxage-list Command (Hidden). show ip ospf neighbor Command. show ip ospf neighbor ip address Command. show ip ospf neighbor int ip-address Command. show ip ospf neighbor detail Command. show ip ospf virtual-links Command. show ip ospf stat Command (Hidden). show ip ospf summary-address Command. clear ip ospf Command. clear ip ospf counters Command. clear ip ospf process Command. clear ip ospf redistribution Command. OSPF debug Commands. When to Use debug Commands. How to Use debug Commands. Timestamping debug Output. Complete OSPF debug Commands. debug ip ospf adjacency Command. debug ip ospf events Command. debug ip ospf flood Command. debug ip ospf hello Command. debug ip ospf lsa-generation Command. debug ip ospf monitor Command (Hidden). debug ip ospf packet Command. debug ip ospf retransmission Command. debug ip ospf spf Command. debug ip routing Command. Summary. Case Study: In the Trenches with OSPF. Problem No. 1. Step 1: Define the Problem. Step 2: Gather Facts. Step 3: Consider Possible Problems. Step 4: Create an Action Plan. Step 5: Implement the Action Plan. Step 6: Gather Results. Step 7: Reiterate the Process, If Needed, in Steps 47. Step 4: Create a New Action Plan. Step 5: Implement the New Action Plan. Step 6 Revisited: Gather Results. Step 7: Reiterate Steps 46. Step 6 Visited Again: Gather Results. Problem #2: Performance Issues. Step 1: Define the Problem. Step 2: Gather Facts. Step 4: Create an Action Plan. Step 5: Implement the Action Plan. Step 6: Gather Results. Case Study Conclusion and Design Tips. Case Study: OSPF Issues and Teasers. OSPF Error Messages. What Do %OSPF-4-ERRRCV Error Messages Mean? What Does the Adv router not-reachable Error Message Mean? OSPF Is Having Neighbor and Adjacency Problems. OSPF Stuck in INIT. OSPF Stuck in EXSTART/EXCHANGE. OSPF Stuck in LOADING. OSPF Stuck in TWO-WAY. OSPF Routes Missing from Routing Table. OSPF Routes Are in the Database but Not in the Routing Table. Miscellaneous Known OSPF Issues. Why Doesnt My Cisco 1600 Router Recognize the OSPF Protocol? Why Doesnt My Cisco 800 Router Run OSPF. Why Is the ip ospf interface-retry 0 Configuration Command Added to All Interfaces? How Do I Produce a Stable OSPF Network with Serial Links Flapping? OSPF Routing Issues.

Review of Interior Gateway Protocols and Exterior Gateway Protocols. Role of IGPs and EGPs in a Network. Introduction to BGP. Characteristic Overview of BGP. Operational Overview of BGP. Preventing Routing Loops. Types of BGP. BGP and OSPF Interaction. Routing Dependencies and Synchronization. Synchronization Is Good. Synchronization Is Bad. Next-Hop Reachability. Redistributing OSPF into BGP. Redistributing OSPF Internal (Intra- and Inter-Area) Routes into BGP. Redistributing OSPF External (Type 1 and 2) Routes into BGP. Redistributing Both Internal and External Routes into BGP. Redistributing OSPF NSSA-External Routes into BGP. Conclusions About BGP. Case Study: BGP. Problem Description. MPLS and OSPF. Background of MPLS. What Is the Benefit of MPLS? Why Not IP Routing or ATM Switching? Conventional Best Effort Routing. MPLS Overview. Label Structure. Label Placement. MPLS Addresses Traffic Engineering. Looking up the Label Path. Configuring OSPF and MPLS. Configuring MPLS. Verifying OSPF and MPLS Operation. Summary.

IV. ADDITIONAL OSPF RESOURCES.

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