《IP路由技术基础 英文版》

Chapter 1 Topology and Router Configurations1

Understanding the Role of Routers in Networks1

The Router Interface2

Network Layer Addresses2

Datagrams3

MAC Addresses4

IP Address Formats5

Network Reference Models6

Understanding Topology and Router Configurations9

RouterA s Configuration10

RouterB s Configuration11

RouterC s Configuration12

Understanding What a Router Does13

Sample Network13

How a Router Knows What to Do15

Choosing Your Routing Protocol16

Understanding How Forwarding Decisions Are Made18

Performing Longest Match Lookups18

Forwarding Decisions for Multipoint Interfaces21

End Systems Sending Packets to Other Subnets23

Summary25

Chapter2 Routing Metrics and Distances27

Primary Activities of Convergence27

Viewing the Invalid Timers in a Routing Table29

Viewing an Expired Invalid Timer in a Routing Table30

Router Still Uses a Path33

Understanding Convergence37

Parallel Paths38

The Effect of Parallel Paths on Convergence38

Looking at Parallel Paths in a Routing Table39

Convergence in Action40

The Routing Table After Convergence41

Step-by-Step Review of Convergence43

Debug Messages and Reality46

When Holddown Is Initiated46

Understanding Parallel Paths and Their Effect on Packet Forwarding47

Process Switching Versus Fast Switching50

Configuring Process Switching51

Configuring Fast Switching52

Understanding the Role of Split Horizon54

Routing Advertisements with Split Horizon Enabled56

Routing Advertisements with Split Horizon Disabled57

Routing Loops Caused by Disabling Split Horizon60

Loss of a Connected Route Versus a Dynamic Route64

Split Horizon s Effect on Multipoint WAN Interfaces65

Using Subinterfaces to Avoid Problems Caused by Split Horizon68

Poison Reverse and Triggered Updates70

IGRP Routing Metrics (Variables) and Cisco Administrative Distances72

IGRP Metrics (Variables)73

Administrative Distances74

Running Multiple Routing Protocols Concurrently76

Altering IGRP S Bandwidth and Delay Variables79

Problems with Manipulating the Delay Variable83

Understanding the Effects of Manipulating the Delay Variable84

Understanding the Effects of Manipulating the Bandwidth Variable87

Calculating IGRP Metrics90

Summary93

Chapter3 Discontiguous Networks, Summarization, and Subnet 095

Introduction to Terminology96

Discontiguous Networks Using RIP and IGRP98

Understanding How a Router Derives thd Correct Masks99

Understanding Summarization (Summarized Routes)103

Understanding Subnet 0104

Summarized Routes Versus Subnet 0105

Summarization Caused by Discontiguous Networks in Action106

RIP Cannot Reach Discontiguous Subnets107

Discontiguous Networks, Subnet 0, and Summarization Using IGRP109

Discontiguous Networks Using Two Routers111

Discontiguous Networks Using Three Routers112

When Connectivity Is Possible112

When Connectivity Is Not Possible120

Alternating Paths for the First Ping124

Using Other Routing Protocols126

Using Summarization as a Tool127

Summary129

Chapter4 Using IP Unnumbered and VLSM131

Understanding IP Unnumbered133

IP Unnumbered Causes Host Routes and Lost Connectivity133

Host Routes134

Hosts Routes Using DDR135

Configuring IP Unnumbered on Serial Interfaces138

RIP and IGRP Behave the Same139

RIP with IP Unnumbered Configured Properly140

Displaying the Routes140

Sending Routing Updates141

RIP with IP Unnumbered Configured Improperly142

Pinging the Interfaces142

Examples of Routing Updates144

Host Route Problem145

Lost Routes Problem146

Using a Different Subnet Mask and a Different Major Net147

Understanding VLSM153

VLSM Using RIP and IGRP153

VLSM Experiment Using Two Routers154

VLSM Experiment Using Three Routers157

Correctly Configuring VLSM Blocked Routes160

VLSM Summary162

Summary162

Introduction to Default Routing163

Chapter5 Default Routing163

Gateway of Last Resort165

Gateway of Last Resort for a Non-Local Domain168

Gateway of Last ResortFails for a Local Domain169

Gateway of Last Resort Still Works When Links Fail173

Using IP Classless174

In Review175

Using Default and Static Routes in Complicated Networks177

Using Static Routes177

Dealing with Too Much Default Routing Information179

Fixing a Default Gateway Loop185

RIP and 0.0.0.0187

The 0.0.0.0 Default Route187

Using 0.0.0.0 with IGRP198

What to Do Instead of Using 0.0.0.0 with IGRP198

Using End Systems with Multiple Local Gateways203

ICMP Router Discovery Protocol (IRDP) RFC 1256204

End Systems Using RIP205

Cisco s Hot Standby Router Protocol (HSRP)209

Using Floating Static Routes212

Summary215

Chapter 6 IP Troubleshooting Scenarios217

Developing a Troubleshooting Routine217

Using a Troubleshooting Scenario219

Tracing the Route220

Checking the Available Routes220

Using Extended Pings to Track Connectivity223

Other Possible Problems225

An ARP Problem225

Validating End System Routing Tables226

Summary230

Chapter7 Bridging IP Between Dissimilar Media233

Translational Bridging233

MSB Versus LSB234

Bit Swapping MAC Addresses235

ARP Explained237

Translating Bridges and ARP Frames239

ARP in Action240

Vendor-Specific Solutions to ARP243

Static ARPs245

Displaying the Parameters of the ARP.EXE Command245

Displaying the Current ARP Entries246

How to Create a Static ARP Entry and Display It246

Deleting Static ARP Entries246

Summary247

Chapter8 Hexadecimal and Binary Numbering and IP Addressing249

Binary Numbering Versus Decimal Numbering249

Hexadecimal Numbering Versus Decimal Numbering252

Introduction to the 32-B it IP Address255

Classes of Addresses256

Default Subnet Masks for Class A, B, C, and D Addresses257

Understanding Subnet Masks, Subnetting, and Supernetting258

Determining What Subnet Is Being Used263

The Shorthand Subnet Mask Indicator265

Introduction to Supernetting266

Calculating Subnet and Host Combinations267

Summary267

Appendix A RFCs269

How RFCs Work269

RFCs Recommended for Further Study270

RFC2235: HobbesInternet Timeline270

RFC2031: IETF-ISOC Relationship271

RFC2028: The Organizations Involved in the IETF Standards Process271

RFC2200: Internet Official Protocol Standards271

RFC2101: IPv4 Address Behavior Today271

RFC2151: A Primer on Internet and TCP/IP Tools and Utilities271

RFC2027: IAB and IESG Selection, Confirmation, and Recall Process: Operation of the Nominating and R272

RFC2026: The Internet Standards Process: Revision3272

RFC2008: Implications of Various Address Allocation Policies for Internet Routing272

RFC1935: What Is the Internet, Anyway?272

RFC1925: The Twelve Networking Truths272

RFC1812: Requirements for IP Version 4 Routers273

RFC1917: An Appeal to the Internet Community to Return Unused IP Networks (Prefixes) to the IANA273

RFC1878: Variable Length Subnet Table for IPv4273

RFC1923: RIPv1 Applicability Statement for Historic Status273

RFC1918: Address Allocation for Private Internets273

RFC1631: The IP Network Address Translator (NAT)274

RFC1601: Charter of the Internet Architecture Board (IAB)274

RFC1508: Guide to Network Resource Tools274

RFC1393: Traceroute Using an IP Option274

RFC1256: ICMP Router Discovery Messages274

RFC1058: Routing Information Protocol275

RFC826: An Ethernet Address Resolution Protocol275

RFC1700: Assigned Numbers275

RFC1149: A Standard for the Transmission of IP Datagrams on Avian Carriers275

RFC1178: Choosing a Name for Your Computer275

RFC1180: A TCP/IP Tutorial275

RFC1543: BOOTP276

RFC2283, RFC1966, RFC1965, RFC1774, RFC1773, RFC1772, RFC1771, RFC1745: Border Gateway Protocol V4 (276

RFC1817, RFC1520, RFC1519, RFC1518, RFC1517: Classless Interdomain Routing (CIDR)276

RFC2132, RFC2131, RFC1534: Dynamic Host Configuration Protocol (DHCP)277

RFC2308, RFC2230, RFC2219, RFC2182, RFC2181, RFC2136, RFC2052, RFC1996, RFC1995, RFC1912, RFC1794, R277

RFC2178, RFC1745, RFC1587, RFC1586, RFC1585, RFC1584, Open Shortest Path First (OSPF)278

RFC1931, RFC1293: Reverse Address Resolution Protocol (RARP) Inverse RARP278

RFC2092, RFC2091, RFC1723, RFC1722, RFC1721, RFC1582, RFC1581: RIP278

RFC2072, RFC2071: Router Renumbering279

RFC2001: TCP/IP (TCP) Slow Start279

RFC1470: TCP/IP Debugging Tools279

Summary280

Index281