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IP Routing

Book Description

This concise guide offers the basic concepts of IP routing, free of hype and jargon. It begins with the simplest routing protocol, RIP, and then proceeds, in order of complexity, to IGRP, EIGRP, RIP2, OSPF, and finally to BGP. New concepts are presented one at a time in successive chapters. By the end, you will have mastered not only the fundamentals of all the major routing protocols, but also the underlying principles on which they are based. The basic information in IP Routing is designed to help you begin configuring protocols for Cisco routers. Although author Ravi Malhotra assumes that readers have a basic understanding of TCP/IP and are somewhat familiar with Cisco router configurations, he also assumes that you find some or all of these protocols difficult to work with. His book presents concepts simply, as nuts and bolts. Malhotra's use of plain language, analogy, and the recurring example of an imaginary network, which grows in complexity as the book progresses, will help you understand fundamental concepts behind each protocol. Once you master these concepts, you will benefit from the detailed information contained in Cisco manuals and web pages (such as bug lists, new features, design guides, etc). Depending on your skill level, you can either read IP Routing from cover to cover or use it as a reference for any of the protocols presented. The book describes administrative tools available to all the routing protocols, including those that block the advertisement of routing updates, and those that set up preferences for one routing protocol over another. Honed by years of teaching Data Communications at major universities and managing IP networks in production environments, Ravi Malhotra's knowledge of this subject makes IP Routing is the ideal primer to Internet routing protocols.

Table of Contents

  1. IP Routing
    1. Preface
      1. Audience
      2. Organization
      3. Conventions Used in This Book
      4. How to Contact Us
      5. Acknowledgments
    2. 1. Starting Simple
      1. What Is IP Routing?
      2. Directly Connected Networks
      3. Static Routing
      4. Dynamic Routing
      5. The Routing Table
      6. Underlying Processes
      7. Summing Up
    3. 2. Routing Information Protocol (RIP)
      1. Getting RIP Running
      2. How RIP Finds Shortest Paths
        1. RIP Update
        2. RIP Metric
        3. Processing RIP Updates
        4. Steady State
        5. Parallel Paths
        6. Process Switching
        7. Fast Switching
      3. Convergence
        1. Speeding Up Convergence
          1. Split horizon
          2. Counting to infinity
          3. Triggered updates
          4. Poison reverse
          5. Setting timers
      4. Subnet Masks
      5. Route Summarization
      6. Default Route
        1. Routes to hosts
      7. Fine-Tuning RIP
      8. Summing Up
    4. 3. Interior Gateway Routing Protocol (IGRP)
      1. Getting IGRP Running
      2. How IGRP Works
        1. IGRP Autonomous System Number
        2. IGRP Metric
          1. Interface bandwidth, delay, reliability, load, and MTU
          2. Modifying interface bandwidth, delay, and MTU
          3. IGRP routing update
          4. Path bandwidth, delay, reliability, load, and MTU
          5. IGRP composite metric
          6. Modifying IGRP metrics
          7. Processing IGRP updates
        3. Parallel Paths
          1. Unequal metric (cost) load balancing
        4. Steady State
      3. Speeding Up Convergence
        1. Setting Timers
        2. Disabling IGRP Hold-Downs
      4. Route Summarization
      5. Default Routes
        1. Multiple Default Routes
      6. Classful Route Lookups
      7. Summing Up
    5. 4. Enhanced Interior Gateway Routing Protocol (EIGRP)
      1. Getting EIGRP Running
      2. EIGRP Metric
      3. How EIGRP Works
        1. Neighbor Relationship
        2. Reliable Transport Protocol
        3. Diffusing Update Algorithm (DUAL)
          1. Reported distance
          2. Feasible distance and successor
          3. Feasibility condition and feasible successor
          4. Loop freedom
          5. Topology table
          6. Convergence in DUAL -- local computation
          7. Convergence in DUAL -- diffusing computation
        4. Protocol-Dependent Module
        5. EIGRP Packet Format
          1. Internal routes
          2. External routes
      4. Variable Length Subnet Masks
      5. Route Summarization
        1. Automatic Summarization
        2. Manual Summarization
      6. Default Routes
      7. Troubleshooting EIGRP
        1. Verifying Neighbor Relationships
        2. Stuck-in-Active
          1. Increase active timer
        3. EIGRP Bandwidth on Low-Speed Links
        4. Network Logs
        5. IOS Version Check, Bug Lists
        6. Debug Commands
      8. Summing Up
    6. 5. Routing Information Protocol Version 2 (RIP-2)
      1. Getting RIP-2 Running
      2. RIP-2 Packet Format
      3. RIP-1/RIP-2 Compatibility
        1. RIP-1/RIP-2 Interworking
      4. Classful Versus Classless Routing Protocols
        1. VLSM
        2. Use of Subnet Zero
        3. Classless Inter-Domain Routing (CIDR)
      5. Classful Versus Classless Route Lookup
      6. Authentication
      7. Route Summarization
      8. Summing Up
    7. 6. Open Shortest Path First (OSPF)
      1. Getting OSPF Running
      2. OSPF Metric
      3. Definitions and Concepts
        1. Backbone Area
        2. Backbone Router
        3. Area or Regular Area
        4. Internal Router
        5. Area Border Router (ABR)
        6. Autonomous System Boundary Router (ASBR)
        7. Stub Area
        8. Totally Stubby Area
        9. Not So Stubby Area (NSSA)
        10. OSPF Topological Database
        11. OSPF Route Types
      4. How OSPF Works
        1. Neighbor Discovery: The Hello Protocol
          1. Router ID
          2. Area ID
          3. Checksum
          4. Authentication
          5. Network mask
          6. Hello-interval
          7. Options
          8. Router priority
          9. Router dead-interval
          10. Designated router (DR)
          11. Backup designated router
          12. Neighbor router ID list
        2. DR/BDR Election
        3. Interface State
        4. Neighbor Relationship
        5. Database Exchange
          1. Router LSA (type 1)
          2. Network LSA (type 2)
          3. Summary LSA (type 3)
          4. ASBR summary LSA (type 4)
          5. External LSA (type 5)
          6. NSSA external LSA (type 7)
          7. Flooding of LSAs
      5. Route Summarization
        1. Summarizing at the ABR (Inter-Area Summarization)
        2. Summarizing at the ASBR (or External Route Summarization)
      6. Default Routes
      7. Virtual Links
      8. Demand Circuits
      9. Stub, Totally Stubby, and Not So Stubby Areas
        1. Stub Areas
        2. Totally Stubby Areas
        3. NSSAs
      10. NBMA Networks
      11. OSPF Design Heuristics
        1. OSPF Hierarchy
        2. IP Addressing
        3. Router ID
        4. DR/BDR
        5. Backbone Area
        6. Number of Routers in an Area
        7. Number of Neighbors
        8. Route Summarization
        9. VLSM
        10. Stub Areas
        11. Virtual Links
        12. OSPF Timers
      12. Troubleshooting OSPF
        1. OSPF Area IDs
        2. OSPF Does Not Start
        3. Verifying Neighbor Relationships
        4. Route Summarization
        5. Overloaded Routers
        6. SPF Overrun
        7. Using the LS Database
        8. Network Logs
        9. Debug Commands
      13. Summing Up
    8. 7. Border Gateway Protocol 4 (BGP-4)
      1. Background
        1. AS Types
        2. Gluing AS to AS... Physical Connectivity in the Internet
        3. Internet Registries: IP Addresses and AS Numbers
        4. Classless Inter-Domain Routing (CIDR)
        5. Acquiring an IP Address
        6. Acquiring an AS Number
      2. Getting BGP Running
      3. How BGP Works
        1. Starting BGP
        2. Neighbor Relationship
        3. BGP Message Types
          1. Open
          2. Update
          3. Notification
          4. Keepalive
        4. Originating Routes
        5. E-BGP Versus I-BGP
        6. Synchronization
        7. The BGP Table
        8. Attributes
          1. ORIGIN (type code 1)
          2. AS-PATH (type code 2)
          3. NEXT-HOP (type code 3)
          4. MED (type code 4)
          5. Weight
          6. LOCAL-PREF (type code 5)
          7. Atomic Aggregate (type code 6)
          8. Aggregator (type code 7)
          9. Community
        9. Path Selection
      4. Load Balancing
      5. Route Filtering
        1. Filtering by Prefix (Address/Mask) Information
        2. Filtering by AS-PATH Information
      6. Connecting to the Internet
        1. Design Alternatives
        2. A Case Study
      7. Choosing an ISP
        1. Services
        2. Network Architecture
        3. Addressing/Routing
        4. Operations
        5. Price
      8. Troubleshooting BGP
      9. Summing Up
    9. 8. Administrative Controls
      1. Filter Routing Information
        1. Block All Updates on an Interface
        2. Filter the Routes Sent out in Updates
        3. Filter the Routes Received in Updates
        4. Apply an Offset to a Routing Metric
      2. Rate the Trustworthiness of a Routing Information Source
      3. Redistribute Routes
        1. How to Redistribute
        2. Many Pitfalls...
        3. ... and a Couple of Strategies
      4. Maximum Number of Paths
      5. Summing Up
    10. Index
    11. Colophon