BGP. Building Reliable Networks with the Border Gateway Protocol (e-book) Dąbrowa Górnicza

Border Gateway Protocol (BGP) is the routing protocol used to exchange routing information across the Internet. It makes it possible for ISPs to connect to each other and for end-users to connect to more than one ISP. BGP is the only protocol that is designed to deal with a network of the Internet's size, and the only protocol that can deal well with having multiple connections to unrelated routing domains.This book is a guide to all aspects of BGP: the protocol, its configuration and operation in an Internet environment, and how to troubleshooting it. The book also describes how to secure BGP, and how BGP can be used as a tool in combating Distributed Denial of Service (DDoS) attacks. Although the examples throughout this book are for Cisco routers, the techniques discussed can be applied to any BGP-capable router.The topics include:Requesting an AS number and IP addressesRoute filtering by remote ISPs and how to avoid thisConfiguring the initial BGP setupBalancing the available incoming or outgoing traffic over the available connectionsSecuring and troubleshooting BGPBGP in larger networks: interaction with internal routing protocols, scalability issuesBGP in Internet Service Provider networksThe book is filled with numerous configuration examples with more complex case studies at the end of the book to strengthen your understanding. BGP is for anyone interested in creating reliable connectivity to the Internet. Spis treści: BGP SPECIAL OFFER: Upgrade this ebook with OReilly Preface Intended Audience Whats in This Book? How to Read This Book Conventions Used in This Book How to Contact Us Acknowledgments 1. The Internet, Routing, and BGP Topology of the Internet The NSFNET Backbone Commercial Backbones and NAPs The Rest of the World Transit and Peering Classification of ISPs TCP/IP Design Philosophy The IP Protocol The Routing Table Routing Protocols Multihoming 2. IP Addressing and the BGP Protocol IP Addresses Subnetting and VLSM CIDR: Classless Inter-Domain Routing Interdomain Routing History The BGP Protocol Open Message Update Message Notification and Keepalive Messages BGP States Propagation of BGP Routes How BGP Selects Routes The route-selection algorithm BGP tie-breaking rules Multiprotocol BGP Routing Multicast IPv6 MBGP and MPLS VPNs Interior Routing Protocols RIP IGRP and EIGRP OSPF IS-IS Interaction Between Routing Protocols 3. Physical Design Considerations Availability Single points of failure Common sense Testing Selecting ISPs Bandwidth Minimum Bandwidth Required Burst Bandwidth and Queuing Delays Calculating Bandwidth, Step by Step Router Hardware Host-Based Routers Multilayer Switches Memory and the Routing Table Performance Anticipating Growth Failure Risks Water Power Failure Building a Wide Area Network The Likelihood of Concurrent Fiber Cuts Network Topology Design A Design Model The Topology 4. IP Address Space and AS Numbers The Different Types of Address Space Provider-Independent Address Space Your Own Provider Aggregatable Block Address Space From an ISP Requesting Address Space Renumbering IP Addresses The AS Number Routing Registries Routing Policy Specification Language 5. Getting Started with BGP Enabling BGP How to Announce an Address Block Configuring the Router Monitoring BGP Clearing BGP Sessions Soft Reconfiguration Inbound Route Refresh Filtering Routes Filter Lists Distribute Lists Prefix Lists Internal BGP Enabling iBGP Default Routes Next Hop Processing Synchronizing with the IGP The Internal Network Ciscos Hot Standby Routing Protocol Full BR2 Configuration RPSL Routing Policy Minimizing the Impact of Link Failures eBGP Multihop 6. Traffic Engineering Knowing Which Route Is Best Finding High- and Low-Quality Routes Is the Highest-Bandwidth Route Best? Route Maps Setting the Local Preference Manipulating Inbound AS Paths Inbound Communities RPSL Routing Policy BGP Load Balancing Traffic Engineering for Incoming Traffic Setting the MED Prepending Outbound AS Paths The Effect of AS Path Prepending Setting Outbound Communities Well-known communities Common community actions Influencing the Local Preference in Upstream ASes Prepending the AS Path Announcing More Specific Routes Queuing, Traffic Shaping, and Policing TCP Congestion Control Slow start Congestion avoidance Fast retransmit and fast recovery TCP Under Packet Loss and Delay Conditions Queuing First in, first out Weighted fair queuing Random early detect Priority queuing Custom queuing Traffic Shaping and Rate Limiting 7. Security and Integrity of the Network Passwords and Security Telnet Versus SSH Software Software Lifecycle Cisco IOS Versions Protecting BGP Avoiding Black Holes Denial-of-Service Attacks Identifying Attacking Packets Tracking Down and Stopping the Source Filtering DoS Traffic Rate-Limiting DoS Traffic Deflecting DoS Traffic Using BGP 8. Day-to-Day Operation of the Network The Network Operations Center The NOC and the Help Desk Contacting the NOC NOC Hardware Facilities SNMP Management Network-Management Suites Product-Specific Management Software Generic SNMP Tools MRTG BGP-4 Management Information Base Router Names General IP Network Management Logging Version Control The Network Time Protocol Scheduled Reloads 9. When Things Start to Go Down: Troubleshooting Keeping a Clear Head Managing the Troubleshooting Process Dealing with Service Providers Physical and Datalink Layer Problems Broken Cable or Circuit Link status and keepalives Last input and loops Line encoding and framing Power and Equipment Failure Poor Network Performance Too much traffic High CPU load Ethernet collisions, broadcasts, and loops Too many errors CRC errors on ATM Ethernet errors because of duplex or speed mismatch Routing and Reachability Problems BGP Session Is Down BGP Session Is Unstable Address Blocks Arent Announced Filters Further Upstream Outgoing Traffic Not Going Out Black Holes Is the Black Hole Incoming or Outgoing? Transit from Nontransit AS Traffic Is Filtered Broken Upstream AS Announcing Your RoutesWith a Vengeance DNS Problems 10. BGP in Larger Networks Peer Groups Using Loopback Addresses for iBGP iBGP Scaling Route Reflectors Confederations Dampening Route Flaps OSPF as the IGP Redistributing Routing Information Redistributing static and connected into OSPF Redistributing BGP into OSPF Redistributing OSPF into BGP Redistributing BGP into OSPF into BGP Redistributing static and connected routes into BGP Traffic Engineering in the Internal Network Network Partitions IP Tunnels and Path MTU Discovery 11. Providing Transit Services Route Filters Communities Setting the Local Preference Fine-Grained Path Prepending Setting Communities on Incoming Routes Community Overview In Routing Registry Anti-DoS Measures A Community for Black-Holing Preemptive Anti-DoS Measures Customers with Backup Connections Simple Backups More Complex Backups: BGP Providing IPv6 and Multicast IPv6 Multihoming Multicast 12. Interconnecting with Other Networks Peering Internet Exchanges, NAPs, and MAEs Connecting to an Internet Exchange The Business of Peering Where Does the Traffic Go? The Politics of Peering Multilateral Peering Connecting to the Exchange Connecting to More Exchange Points Rejecting Unwanted Traffic IX Subnet Problems Talking to Other Network Operators Exchange Point Future A. Cisco Configuration Basics IP Configuration Essentials Source Routing and Directed Broadcasts Antispoofing Filters CIDR and VLSM B. Binary Logic, Netmasks, and Prefixes C. Notes on the IPv4 Address Space Glossary Index About the Author Colophon SPECIAL OFFER: Upgrade this ebook with OReilly