IP Routing on Cisco IOS, IOS XE, and IOS XR: An Essential Guide to Understanding and Implementing IP Routing Protocols

About This eBook
Title Page
Copyright Page
About the Authors
About the Technical Reviewers
Dedications
Acknowledgments
Contents at a Glance
Contents
Icons Used in This Book
Command Syntax Conventions
Foreword
Introduction
	Who Should Read This Book?
	How This Book Is Organized
Final Words
Part I: Network Fundamentals
	Chapter 1. Introduction to the Operating Systems
		IOS, IOS XE, and IOS XR Software Architecture
			IOS
				Kernel and OS Scheduling
				Memory Management
				Software Packaging
			IOS XE
				Kernel and OS Scheduling
				Memory Management
			IOS XR
				Kernel and OS Scheduling
				Memory Management
				Software Packaging
			Debugging
		CLI and Configuration
			IOS
				User Mode
				Privileged Mode
				Global Configuration Mode
				Configuration Archiving
				Configuration Replace
			IOS XR
				Viewing Changes in the SysDB
				Commit Label
				Commit Replace
				Failed Commits
				Configuration Rollback
				Commit Confirmed
				Multiple Commit Options
				Loading Files for Changes
				Hierarchical Configuration
				PWD
				Root
		Summary
		References in This Chapter
	Chapter 2. IPv4 Addressing
		IP Fundamentals
		Understanding Binary
		Address Classes
		Subnet Masks and Subnetting
			Subnet Mask Purpose
			Calculating Usable IP Addresses
			Network Prefix Notation
			Subnetting
				Subnet Field
				Subnet Math
			Subnet Design
		Classless Interdomain Routing
			Classful Versus Classless Routing
				Classful Routing
				Classless Routing
			Variable-Length Subnet Masks
			Summarization
		Private IP Addressing
		Special IP Addresses
		IPv4 Address Configuration
		Wildcard Subnet Masks
		Summary
		References in This Chapter
	Chapter 3. How a Router Works
		IP Routing
			Distance Vector Algorithms
			Enhanced Distance Vector Algorithm
			Link-State Algorithms
			Path Vector Algorithm
			Routing Table
				Prefix Length
				Administrative Distance
				Metrics
			Virtual Routing and Forwarding
		IP Packet Switching
			Process Switching
			Cisco Express Forwarding
				Software CEF
				Hardware CEF
		Planes of Operation
		Summary
		References in This Chapter
Part II: Routing Protocols
	Chapter 4. Static Routing
		Connected Networks
		Secondary Connected Networks
		Static Routing Fundamentals
			Point-to-Point Interfaces
			Broadcast Interfaces
			Default Route
			Floating Static Routing
			Recursive Lookup
			Multihop Routing
				Single Recursive Lookup
				Multiple Recursive Lookups
			Problems with Static Route Recursion
		Null Interface
		Static VRF Routes
		Summary
		References in This Chapter
	Chapter 5. EIGRP
		EIGRP Fundamentals
		EIGRP Neighbors
			Inter-Router Communication
			Forming EIGRP Neighbors
		Classic EIGRP Autonomous System Configuration
			IOS network Statement
			IOS XR
			Passive Interfaces
			Sample Topology and Configuration
			Confirmation of Interfaces
			Verification of EIGRP Neighbor Adjacencies
			Display of Installed EIGRP Routes
		Router ID
		EIGRP Terminology
		Topology Table
		Path Metric Calculation
			Custom K Values
			Interface Delay Settings
			Load Balancing
			EIGRP Wide Metrics
		Failure Detection and Timers
			Convergence
			Stuck in Active
		Stub
			Design Considerations with EIGRP Stubs
		Summarization
			Interface-Specific Summarization
			Summarization Metrics
			Advertising a Default Route
			Automatic Summarization
		Authentication
			Enabling Authentication on the interface
			Key Chain Configuration
			WAN Considerations
				IP Bandwidth Percent
			Split Horizon
			Next-Hop Self
		EIGRP Named Configuration
			Address Family Instance Configuration
			Address Family Interface Configuration
			Address Family Topology Configuration
		Summary
		References in This Chapter
	Chapter 6. OSPF
		OSPF Fundamentals
			Inter-Router Communication
			OSPF Hello Packets
			Router ID
			Neighbors
			Forming OSPF Neighbor Adjacencies
			Basic OSPF Configuration
				IOS network Statement
				IOS Interface Specific
				IOS XR
			Passive Interfaces
			Sample Topology and Configuration
			Confirmation of Interfaces
			Verification of OSPF Neighbor Adjacencies
			Verification of OSPF Routes
		Designated Router and Backup Designated Router
			Designated Router Elections
			DR and BDR Placement
		Failure Detection
			Hello Timer
			Dead Interval Timer
			Verifying OSPF Timers
			OSPF Fast Packet Hellos
		OSPF Network Types
			Broadcast
			Non-Broadcast
			Point-to-Point Networks
			Point-to-Multipoint Networks
			Loopback Networks
			Review of OSPF Network Types
			OSPF Adjacency with Different OSPF Network Types
		Link Costs
		Authentication
			IOS Support for OSPF Authentication
			IOS XR Support for OSPF Authentication
		Summary
		References in This Chapter
	Chapter 7. Advanced OSPF
		Areas
			Area ID
			OSPF Route Types
				External OSPF Routes
		Link-State Announcements
			LSA Age and Flooding
			LSA Types
				LSA Type 1: Router Link
				LSA Type 2: Network Link
				LSA Type 3: Summary Link
				LSA Type 5: External Routes
				LSA Type 4: ASBR Summary
				LSA Type 7: NSSA External Summary
				LSA Type Summary
		OSPF Path Selection
			Intra-Area Routes
			Interarea Routes
			External Route Selection
			E1 and N1 External Routes
			E2 and N2 External Routes
			Equal Cost Multi-Path
		Summarization of Routes
			Interarea Summarization
			External Summarization
			Default Route
		OSPF Stubby Areas
			Stub Areas
			Totally Stubby Areas
			Not-So-Stubby Areas
			Totally NSSA Areas
		Virtual Links
		Discontiguous Network
		Multi-Area Adjacency
		Prefix Suppression
		Summary
		References in This Chapter
	Chapter 8. IS-IS
		IS-IS Fundamentals
			Areas
			OSI Addressing
				Inter-Domain Part
				Domain Specific Part
				NET Addressing
		Inter-Router Communication
			IS Protocol Header
			TLVs
			IS PDU Addressing
			Hello Packets
			Link-State Packets
				LSP Lifetime
				LSP ID
				LSP Sequence
				Attribute Fields
				LSP Packet and TLVs
			IS-IS Neighbor
				Ethernet
				Point-to-Point
		Basic IS-IS Configuration
			IOS
			IOS XR
			Sample Topology and Configuration
			Confirmation of IS-IS Interfaces
			Verification of IS-IS Neighbor Adjacencies
			Verification of IS-IS Routes
		Designated Intermediate System
			DIS Elections
			DIS Placement
		Point-to-Point Adjacency on Broadcast Media
		Link State Packet Database
			Viewing the LSPDB
				Non-Pseudonode LSPs
				Pseudonode LSPs
			Building the Topology
			Viewing the Topology
			SPF Calculations
		Passive Interfaces
		Removal of Hello Padding
		Failure Detection
			Hello Timer
			Hello Multiplier and Holding Timer
		Authentication
			IS-IS Hello Authentication
			IS-IS LSP Authentication
		Summary
		References in This Chapter
	Chapter 9. Advanced IS-IS
		Advanced IS-IS Routing
			Route Leaking
			Backbone Continuity
			Loop Prevention
			Router-Specific IS-IS Levels
			Interface Specific IS-IS Levels
		Path Selection
			Equal Cost Multi-Path
			Interface Metrics
			Overload Bit
		Summarization
		Default Routes
		Prefix Suppression
		Summary
		References in This Chapter
	Chapter 10. Border Gateway Protocol
		BGP Fundamentals
			Autonomous System Numbers
			Path Attributes
			Loop Prevention
			Address Families
		Inter-Router Communication
			Open Messages
				Hold Time
				BGP Identifier
			Keepalive Messages
			Update Messages
			Notification Messages
			BGP Sessions
		BGP Neighbor States
			Idle State
			Connect State
			Active State
			OpenSent State
			OpenConfirm State
			Established State
		Basic BGP Configuration
			IOS
			IOS XR
			Verification of BGP Sessions
			Prefix Advertisement
			Receiving and Viewing Routes
		iBGP
			iBGP Full-Mesh Requirement
			Peering via Loopback Addresses
		eBGP
			eBGP and iBGP Topologies
			Next-Hop Manipulation
		iBGP Scalability
			Route Reflectors
				Loop Prevention in Route Reflectors
				Out-of-Band Route Reflectors
			Confederations
		Failure Detection
		Security
			eBGP Multihop
			TTL Security
		Summary
		References in This Chapter
Part III: Advanced Routing Techniques
	Chapter 11. Route Maps and Route Policy
		Access Control Lists
			Standard ACLs
			Extended ACLs
				IGP Network Selection
				BGP Network Selection
		Prefix Matching
			Prefix Lists
			Prefix Sets
			Regular Expressions
				_
			^
			$
			[ ]
			-
			[^]
				
			.
			+
			?
			*
			Looking Glass and Route Servers
		AS_Path Access List
		IOS XR AS_Path Selection Options
			is-local
			length
			unique-length
			passes-through
			neighbor-is
			originates-from
			AS Path Set
		Route Maps
			Conditional Matching
				Multiple Conditional Match Conditions
				Complex Matching
			Optional Actions
			Continue
			Route Map Examples
		Routing Policy Language
			Route Policy Structure
			Match Statements
			Attribute Modification
			Common Route Policy Structure
			Boolean Operators
				Negation
				Conjunction
				Disjunction
				Order of Processing
			Comparing Prefix Sets to Prefix Lists
			Parameterization
			Route Policy Nesting
			Original Value
			Editors
			RPL Examples
			RPL Verification
				Redistribution RPL Verification
				BGP RPL Verification
		Summary
		References in This Chapter
	Chapter 12. Advanced Route Manipulation
		Conditional Routing of Packets
			Policy-Based Routing Configuration
			Access-List-Based Forwarding Configuration
			Local PBR
		Administrative Distance
			Modifying EIGRP AD
			Modifying OSPF AD
			Modifying IS-IS AD
			Modifying BGP AD
		Route Filtering and Manipulation
			EIGRP Filtering by Prefix
			EIGRP Filtering by Hop Count
			EIGRP Offset Lists
			OSPF Filtering
			OSPF Filtering
			IS-IS Filtering
			BGP Filtering
			Clearing BGP Connections
		Summary
		References in This Chapter
	Chapter 13. Route Redistribution
		Redistribution Basics
			Redistribution Is Not Transitive
			Sequential Protocol Redistribution
			Routes Must Exist in the RIB
			Metrics
		Protocol-Specific Configuration
			Source-Specific Behaviors
				Connected Networks
				IS-IS
				BGP
			Destination-Specific Behaviors
				EIGRP
				OSPF
				IS-IS
				BGP
		Challenges with Redistribution
			Route Feedback
			Suboptimal Routing
			Invalid Routing Tables
			Routing Loops
			Methods to Avoid Routing Loops
				Prefix Filtering
				Tagging
				Increase Seed Metrics
				Administrative Distance
				Summarization on Redistributing Router
			Solutions to Redistribution Challenges
		Summary
		References in This Chapter
Part IV: Advanced BGP
	Chapter 14. Advanced BGP
		BGP Communities
			Enabling BGP Community Support
			Well-Known Communities
				Internet
				No_Export
				No_Advertise
				No_Export_SubConfed
			Conditionally Matching BGP Communities
				Community Set
				Inline
				Setting Private BGP Communities
		Route Summarization
			Aggregate Address
			Flexible Route Suppression
				Selective Prefix Suppression
				Leaking Suppressed Routes
			Atomic Aggregate
			Route Aggregation with AS_SET
			Route Aggregation with Selective Advertisement of AS_Set
		Default Route Advertisement
		Default Route Advertisement Per Neighbor
		Conditional Route Advertisement
		Outbound Route Filtering
		Backdoor Networks
		Maximum Autonomous System
		Maximum Prefix
		Remove Private Autonomous System
		Allow Autonomous System
		Local Autonomous System
		Configuration Scalability
			IOS Peer Groups
			IOS Peer Templates
			IOS XR Configuration Templates
		Summary
		References in This Chapter
	Chapter 15. BGP Best Path Selection
		BGP Best Path Overview
			Weight
			Local Preference
			Locally Originated via Network or Aggregate Advertisement
			Accumulated Interior Gateway Protocol
			Shortest AS_Path
			Origin Type
			Multi-Exit Discriminator
				Missing MED behavior
				Always Compare Med
				BGP Deterministic MED
			eBGP over iBGP
			Lowest IGP Metric
			Prefer the Oldest EBGP Path
			Router ID
			Minimum Cluster List Length
			Lowest Neighbor Address
		BGP ECMP
			eBGP and iBGP Multipath
			eiBGP Multipath
				R1
				R2
				XR3
				XR4
				XR5
			AS_Path Relax
		Suboptimal Routing with Route Reflectors
			Additional Route Reflector
			Shadow Route Reflector
			Shadow Session Route Reflector
			BGP Add-Path
		Summary
		Further Reading
		References in This Chapter
Part V: Multicast
	Chapter 16. IPv4 Multicast Routing
		Multicast Fundamentals
		Multicast Addressing
			Layer 2 Multicast Addresses
		Internet Group Management Protocol
			IGMP Snooping
			IGMPv2
			IGMPv3
		Multicast Distribution Trees
			Source Trees
			Shared Trees
		Protocol Independent Multicast
			PIM Dense Mode
			PIM Sparse Mode
				PIM Shared and Source Path Trees
				Shared Tree Join
				Source Registration
				PIM SPT Switchover
				Designated Routers
		Rendezvous Points
			Static RP
			Auto-RP
				Candidate RPs
				RP Mapping Agents
			PIM Bootstrap Router
				Candidate RPs
		Reverse Path Forwarding
		PIM Forwarder
		Basic Multicast Configuration
			Configure Rendezvous Points
				Static RP
				Auto-RP
				BSR
		Multicast Verification
		Bidirectional PIM
			Bidir-PIM Designated Forwarder
		Summary
		References in This Chapter
	Chapter 17. Advanced IPv4 Multicast Routing
		Interdomain Multicast Routing
			Multiprotocol BGP
			Multicast Source Discovery Protocol
				MSDP Source Active Message Types
				SA Messages
				Keepalive Messages
				MSDP Peers
				MSDP Verification
				MSDP Stub Networks
		Rendezvous Point Redundancy
			Auto-RP with Multiple RPs
				Auto-RP Group Filtering
			BSR with Multiple RPs
				BSR Group Filtering
				BSR RP Hash Algorithm
			Static RP with Multiple RPs
			Anycast RP
		Source Specific Multicast
			SSM Mapping
				DNS SSM Mapping
				Static SSM Mapping
		Multicast Security
			Auto-RP Scoping
			Multicast Boundaries
				Administratively Scoped Boundaries
				Auto-RP Multicast Boundaries
				BSR Multicast Boundaries
			Auto-RP Cisco-RP-Announce Message Filtering
			PIM-SM Source Registration Filtering
			PIM-SM Accept RP
			PIM Neighbor Control
			PIM Register Rate Limit
		Multicast Traffic Engineering
			RPF Rules
			Static Mroutes
			MBGP
			Static IGMP Joins
		Multicast Troubleshooting
			Mtrace
		Summary
		References in This Chapter
Part VI: IPv6
	Chapter 18. IPv6 Addressing
		IPv6 Address Structure
			Text Representation Address Abbreviation
			IPv6 Hexadecimal to Binary Conversion
		IPv6 Address Types
			Unicast
			Global Unicast
			Unique Local Unicast
			Link-Local Unicast
			Anycast
			Multicast
			Special IPv6 Addresses
		Neighbor Discovery Protocol
			Router, Prefix, and Parameter Discovery.
			Redirect
			IPv6 Stateless Address Autoconfiguration
				Extended Unique Identifier
				SLAAC Router Configuration
				RA Options for DNS
			Stateless DHCPv6
				IOS Stateless DHCPv6 Configuration
				IOS XR Stateless DHCPv6 Configuration
				Stateless DHCPv6 Verification
			Stateful DHCPv6, Relay Agent, and Relay Proxy
				IOS Relay Agent Configuration
				IOS Relay Agent Verification
				IOS XR Proxy Agent Configuration
				IOS XR Proxy Agent Verification
				IOS Stateful DHCPv6 Server Configuration
				IOS XR Stateful DHCPv6 Server Configuration
				Stateful DHCPv6 Server Verification
			IPv6 Address Resolution and Neighbor Unreachability Detection
			Duplicate Address Detection
		Summary
		References in This Chapter
	Chapter 19. IPv6 Routing
		Static Routing
			Static Route Configuration
			Static Route Reference Chart for IPv6
		EIGRPv6
			EIGRPv6 Inter-Router Communication
			EIGRPv6 Configuration
				IOS EIGRPv6 Autonomous System Configuration
				IOS EIGRPv6 Hierarchical Configuration
				IOS XR EIGRPv6 Configuration
				EIGRPv6 Verification
			Summarization
			Default Route
			Route Filtering
			EIGRP Configuration Command Reference Chart for IPv6
		OSPFv3
			OSPFv3 Inter-Router Communication
			OSPFv3 Link-State Advertisement
			OSPFv3 LSA Flooding Scope
			OSPFv3 Configuration
				IOS OSPFv3 Configuration
				IOS XR OSPFv3 Configuration
				OSPFv3 Verification
			OSPFv3 Authentication
			OSPFv3 Multiple Instances
			OSPFv3 Configuration Command Reference Chart for IPv6
		Integrated IS-IS for IPv6
			IS-IS Inter-Router Communication
			IS-IS Type-Length-Value
			IS-IS Topology Modes
			IS-IS Configuration
				IOS Base Configuration
				IOS XR Base Configuration
				IOS Topology Mode Configuration
				IOS XR Topology Mode Configuration
				Verification
			IS-IS Configuration Reference Chart for IPv6
		Multiprotocol BGP for IPv6
			Inter-Router Communication
			BGP Configuration
				IOS Base Configuration
				IOS XR Base Configuration
			BGP Verification
			IPv6 over IPv4 BGP Sessions
			BGP Configuration Command Reference Chart for IPv6
		IPv6 Route Redistribution
		Summary
		References in This Chapter
	Chapter 20. IPv6 Multicast Routing
		IPv6 Multicast Routing Overview
			IPv6 Multicast Address Mapping into MAC Address
			Enabling Multicast Routing
			Multicast Listener Discovery
			Protocol Independent Multicast
			PIM Sparse Mode
				Static RP
				Bootstrap Router
				Embedded RP
			IPv6 Multicast Verification Commands
			Reverse Path Forwarding
			Multicast Boundary Scope
			PIM Source Specific Multicast
		Summary
		References in This Chapter
Index
Part VII: High Availability
	Chapter 21. High Availability
		Network Convergence Overview
		Continuous Forwarding
			Stateful Switchover
			Nonstop Forwarding and Graceful Restart
				OSPF
				IS-IS
				EIGRP
				BGP
			Nonstop Routing
				NSR for OSPF
				NSR for IS-IS
				NSR for BGP
			Nonstop Forwarding and Nonstop Routing Together
		Failure Avoidance
			Route Flap Dampening
				IP Event Dampening
				BGP Dampening
		Event-Driven Failure Detection
			Carrier Delay
			BFD
				Asynchronous Mode Without Echo
				Asynchronous Mode with Echo
				BFD Configuration for OSPF, IS-IS, and EIGRP
				BFD Configuration for BGP
				BFD Configuration for BGP Multihop
				BFD Configuration for Static Routes
		Fast Routing Convergence
			IS-IS Convergence Tuning
			OSPF Convergence Tuning
			SPF Prefix Prioritization
			BGP Convergence Tuning
				Next-Hop Tracking
				Minimum Route Advertisement Interval
				TCP Performance
		Fast Reroute
			Loop-Free Alternate Fast Reroute
				Loop-Free Condition Rules
				LFA Protection Modes
				OSPF LFA FRR
				IS-IS LFA FRR
				Shared Risk Link Group
			BGP Prefix-Independent Convergence
				BGP PIC Core
				BGP PIC Edge
				BGP PIC Edge Link and Node Protection
				BGP PIC Edge with Next-Hop-Self
				BGP Advertise Best External
				BGP Additional Path
		Summary
		References in This Chapter
Appendixes
	Appendix A. Decimal to Hex to Binary Tables
	Appendix B. BGP Attributes
Code Snippets