Ascolta

The Configuring BGP on Cisco Routers (BGP) v3.2 course provides students with in-depth knowledge of BGP, the routing protocol that is one of the underlying foundations of the Internet and new-world technologies such as Multiprotocol Label Switching (MPLS). This curriculum covers the theory of BGP, configuration of BGP on Cisco IOS routers, detailed troubleshooting information and exercises that provide students with the skills needed to configure and troubleshoot BGP networks in customer environments. Different service solutions in the curriculum cover BGP network design issues and usage rules for various BGP features preparing students to design and implement efficient, optimal and trouble free BGP networks.

Ascolta Advantage

We have included these extras at no additional cost for a full 14-days after the completion of your BGP course in order to help you succeed beyond the classroom:

• Test Preps: Assess your skills and knowledge for the big day when you take your exam!
• 24/7 Online Mentoring: Access to certified experts to help you study day and night via our "Mentored Chat Rooms" and our "Email My Mentor" services. It's like having your own personal instructor whenever and wherever you need help!
• Reference Materials and Labs: Get the complete online version of your course materials for on-the-go reference with simulated labs available 24/7!

Prerequisites

• Completion of Interconnecting Cisco Networking Devices (ICND) or Cisco Certified Networking Associate (CCNA)
• Completion of Building Scalable Cisco Internetworks (BSCI) or equivalent

Target Audience

• System Engineers, Channel Partners/Resellers, Customers

Course Objectives

After completing this course the student should be able to:

• Given a network scenario with multiple domains, configure, monitor and troubleshoot basic BGP to enable interdomain routing
• Given a network scenario where connections to multiple ISPs must be supported, use BGP policy controls to influence the route selection process with minimal impact on BGP route processing
• Given a network scenario where multiple connections must be supported, use BGP attributes to influence the route selection process
• Given customer connectivity requirements, implement the correct BGP configuration to successfully connect the customer's network to the Internet
• Given a typical service provider network with multiple BGP connections to other autonomous systems, enable the provider network to behave as a transit autonomous system
• Given a typical service provider network, identify common BGP scaling issues and enable route reflection and confederations as possible solutions to these issues
• Given a typical BGP network, use available BGP tools and features to optimize the scalability of the BGP routing protocol

Course Outline

The Course Outline is as follows:

Volume 1 

Course Introduction 1

• Cisco Certifications
• Learner Skills and Knowledge
• Learner Responsibilities
• General Administration
• Course Flow Diagram
• Icons and Symbols
• Learner Introductions 

BGP Overview 1-1 

Introducing BGP 1-3 

• Interdomain Routing 1-5
• Example 1-7
• BGP Characteristics 1-9
• Single-Homed Customers 1-13
• Multihomed Customers 1-15
• Transit Autonomous Systems 1-17
• BGP Limitations 1-18
• Summary 1-19

References 1-20
Establishing BGP Sessions 1-21

• BGP Neighbor Discovery 1-23
• Example 1-24
• Establishing a BGP Session 1-26
• BGP Keepalives 1-29 
• Example 1-30
• MD5 Authentication 1-31
• Summary 1-32
• References 1-32

Understanding BGP Path Attributes 1-33

• BGP Path Attributes 1-35 
• Well-Known BGP Attributes 1-36 
• Optional BGP Attributes 1-39 
• AS-Path Attribute 1-41 
• Example 1-42
• Next-Hop Attribute 1-43 
• Example 1-44 
• Summary 1-47 
• References 1-47 

Processing BGP Routes 1-49 

• Receiving Routing Updates 1-51
• Building the BGP Table 1-53 
• BGP Route Selection Criteria 1-54 
•  Example 1-56 
• BGP Route Propagation 1-57 
• Building the IP Routing Table 1-58 
• Advertising Local Networks 1-59 
• Example 1-60 
• Automatic Summarization 1-62 
• Example 1-63 
• Summary 1-65 
• References 1-65 

Configuring Basic BGP 1-67 

• BGP Routing Process 1-69 
• Configuring External Neighbors 1-71 
• Configuring BGP Timers 1-74 
• Configuring MD5 Authentication 1-76 
• Announcing Networks in BGP 1-77 
• Example 1-80 
• Redistributing Routes into BGP 1-81 
• Configuring Classless BGP 1-86 
• Example 1-89 
• Aggregating BGP Networks 1-90 
• Example 1-93 
• Multihomed Customer Problem 1-96 
• Summary 1-98 
• References 1-99 
• Next Steps 1-99 

Monitoring and Troubleshooting BGP 1-101

• Monitoring Overall BGP Routing 1-103 
• Monitoring BGP Neighbors 1-105 
• Monitoring the BGP Table 1-107 
• Debugging BGP 1-109 
• BGP Session Startup Problems 1-112 
• BGP Neighbor Not Reachable 1-113
• Example 1-115 
• BGP Neighbor Not Configured 1-116 
• Example 1-117 
• BGP AS Number Mismatch 1-118 
• Example 1-119 
• Summary 1-120 
• References 1-121 

BGP Transit Autonomous Systems 2-1
Working with a Transit AS 2-3

• Transit AS Tasks 2-5
• External Route Propagation 2-6 
• Internal Route Propagation 2-7 
• Packet Forwarding in an AS 2-8 
• Core Router IBGP Requirements in a Transit AS 2-9 
• Summary 2-10 
• References 2-10 

Interacting with IBGP and EBGP in a Transit AS 2-11

• AS-Path Processing in IBGP 2-13 
• BGP Split Horizon 2-14 
• IBGP Full Mesh 2-15 
• Example 2-16 
• IBGP Neighbors 2-17 
• IBGP Next-Hop Processing 2-19 
• Transit Network Using External Next Hops 2-21 
• Transit Network Using Edge Routers as Next Hops 2-23 
• Example 2-25 
• Differences Between EBGP and IBGP Sessions 2-27 
• Example 2-29 
• Summary 2-30 
• References 2-31 

Forwarding Packets in a Transit AS 2-33

• Packet Forwarding in a Transit AS 2-35 
• Recursive Lookup in Cisco IOS Software 2-37 
• Routing Protocols in a Transit AS 2-39 
• BGP and IGP Interaction 2-41 
• Problems with BGP and IGP Interaction 2-43 
• Summary 2-44 
• References 2-44 

Configuring a Transit AS 2-45

• Configuring IBGP Neighbors 2-47
• Configuring IBGP Sessions Between Loopback Interfaces 2-49
• Configuring BGP Synchronization 2-51 
• Changing the Administrative Distance of BGP Routes 2-52 
• Scalability Limitations of IBGP-Based Transit Backbones 2-54 
• Summary 2-55
• References 2-55
• Next Steps 2-55 

Monitoring and Troubleshooting IBGP in a Transit AS 2-57

• Monitoring IBGP 2-59
• Example 2-61 
• Common IBGP Problems 2-63 
• Troubleshooting IBGP Session Startup Issues 2-64 
• Troubleshooting IBGP Route Selection Issues 2-67 
• Troubleshooting IBGP Synchronization Issues 2-68 
• Summary 2-69 
• References 2-69 

Route Selection Using Policy Controls 3-1 
Using Multihomed BGP Networks 3-3

• Business Requirements of Multihomed BGP Networks 3-5 
• Technical Requirements of Multihomed BGP Networks 3-6 
• BGP Route Selection Without Policies 3-7 
• Example 3-8 
• Multihomed Customer Routing Policies 3-9 
• Influencing BGP Route Selection 3-10 
• BGP Filters 3-12 
• Summary 3-15 
• References 3-16 
• Next Steps 3-16 

Employing AS-Path Filters 3-17

• AS-Path Filtering Scenarios 3-19
• AS-Path Regular Expressions 3-21 
• String Matching 3-22
• Example 3-29 
• Applying AS-Path Filters 3-31 
• Configuring BGP AS-Path Filters 3-32 
• Monitoring AS-Path Filters 3-35
• Summary 3-39 
• References 3-40 
• Next Steps 3-40 

Filtering with Prefix-Lists 3-41

• Requirements for Prefix-Based Filters 3-43 
• Prefix-Lists vs. IP Access-Lists 3-44 
• Configuring Prefix-Lists 3-47
• Example 3-51 
• BGP Filters Implementation 3-52 
• Implementing Prefix-Lists in the BGP Process 3-53 
• Example 3-56 
• Example 3-57 
• Modifying Prefix-Lists 3-58 
• Monitoring Prefix-Lists 3-59 
• Summary 3-62 
• References 3-63 
• Next Steps 3-63 

Using Outbound Route Filtering 3-65

• Outbound Route Filtering 3-67 
• Example 3-68
• Outbound Route Filter Message 3-69 
• Configuring Outbound Route Filtering 3-72 
• Using Outbound Route Filtering 3-75 
• Monitoring Outbound Route Filtering 3-76 
• Summary 3-77 
• References 3-77

Applying Route-Maps as BGP Filters 3-79

• Why Use Route-Maps as BGP Filters? 3-81 
• Route-Map Overview 3-82 
• Prefix-List Use in Route-Maps 3-86 
• BGP Filters 3-87 
• Using Route-Maps as BGP Filters 3-88 
• Monitoring Route-Maps 3-90 
• Summary 3-94 
• References 3-95

Implementing Changes in BGP Policy 3-97

• Traditional Filtering Limitations 3-99 
• BGP Soft Reconfiguration 3-101 o Example 3-102 
• Cisco IOS Commands for Soft Reconfiguration 3-103 
• Monitoring Soft Reconfiguration 3-106 
• Route Refresh 3-107 
• Example 3-110 
• Using Route Refresh 3-111 
• Monitoring Route Refresh 3-112 
• Summary 3-114 
• References 3-115 
• Next Steps 3-115

Volume 2
Route Selection Using Attributes 4-1
Influencing BGP Route Selection with Weights 4-3

• BGP Route Selection Criteria 4-5
• Influencing BGP Route Selection 4-6
• Configuring Per-Neighbor Weights 4-8 
• Example 4-9 
• Changing Weights with Route-Maps 4-11 
• Example 4-12 
• Monitoring BGP Route Selection and Weights 4-14 
• Example 4-15 
• BGP Route Selection and Filtering Tools Summary 4-17 
• Summary 4-18 
• References 4-19 
• Next Steps 4-19

Setting BGP Local Preference 4-21

• Consistent Route Selection Within the AS 4-23
• Example 4-26
• BGP Local Preference 4-27
• Configuring Default Local Preference 4-30 
• Example 4-31 
• Configuring Local Preference with Route-Maps 4-32 
• Example 4-33 
• Monitoring Local Preference 4-34 
• Example 4-35 
• Summary 4-39 
• References 4-39 
• Next Steps 4-39 

Using AS-Path Prepending 4-41 

• Return Path Selection in a Multihomed AS 4-43 
• AS-Path Prepending 4-47 
• Example 4-48 
• AS-Path Prepending Design Considerations 4-50 
• Configuring AS-Path Prepending 4-52 
• Example 4-54 
• Monitoring AS-Path Prepending 4-55 
• AS-Path Filtering Concerns with AS-Path Prepending 4-57 
• Summary 4-60 
• References 4-61

Understanding the BGP Multi-Exit Discriminator 4-63

• Selecting the Proper Return Path 4-65
• MED Propagation in a BGP Network 4-67 
• Changing the Default MED 4-68 
• Changing the MED with Route-Maps 4-69 
• Example 4-70 
• Advanced MED Configuration 4-71 
• Example 4-73 
• Monitoring the MED 4-74 
• Example 4-75 
• Troubleshooting the MED 4-78 
• Summary 4-81 
• References 4-82 
• Next Steps 4-82 

Addressing BGP Communities 4-83

• Selecting the Proper Return Path 4-85 
• BGP Communities Overview 4-86 
• Using Communities 4-89
• Example 4-90 
• Configuring BGP Communities 4-91 
• Configuring Route Tagging with BGP Communities 4-92 
• Example 4-94 
• Configuring Community Propagation 4-95 
• Example 4-96 
• Defining BGP Community-Lists 4-97 
• Example 4-99 
• Matching BGP Communities with Route-Maps 4-100 
• Example 4-102 
• Monitoring Communities 4-103 
• Summary 4-107 
• References 4-108 
• Next Steps 4-108 

Customer-to-Provider Connectivity with BGP 5-1 
Understanding Customer-to-Provider Connectivity Requirements 5-3

• Customer Connectivity Types 5-5 
• Redundancy in Customer Connections 5-6 
• Customer-to-Provider Routing Schemes 5-10 
• Customer Routing 5-11 
• Addressing Requirements 5-14 
• Example 5-16 
• AS Number Allocation 5-17 
• Summary 5-19 
• References 5-20 

Implementing Customer Connectivity Using Static Routing 5-21

• Why Use Static Routing? 5-23
• Characteristics of Static Routing 5-24 
• Example 5-26 
• Designing Static Route Propagation in a Service Provider Network 5-27 
• Static Route Propagation Case Study Parameters 5-29 
• BGP Backup with Static Routes 5-33 
• Floating Static Routes with BGP 5-38 
• Load Sharing with Static Routes 5-41 
• Example 5-44 
• Summary 5-45 
• References 5-46 

Connecting a Multihomed Customer to a Single Service Provider 5-47

• Configuring BGP on Multihomed Customer Routers 5-50
• Example 5-51 
• Conditional Advertising in Multihomed Customer Networks 5-52 
• Example 5-53 
• Configuring BGP on Service Provider Routers 5-54 
• Example 5-56 
• Removing Private AS Numbers 5-57 
• Example 5-59 
• Backup Solutions with BGP 5-60 
• Example 5-61 
• Load Sharing with the Multihomed Customer 5-62 
• Load Sharing with BGP Multipath 5-63 
• Load Sharing with EBGP Multihop 5-65 
• Example 5-67 
• Summary 5-68 
• References 5-69 

Connecting a Multihomed Customer to Multiple Service Providers 5-71

• Configuring BGP for Multihomed Customers 5-73
• Multihomed Customer Address Space Selection 5-76 
• Multihomed Customer AS Number Selection 5-77 
• AS Number Translation 5-79 
• Primary/Backup Link Selection 5-81 
• BGP Incoming Link Selection 5-82 
• Load Sharing with Multiple Providers 5-86 
• Summary 5-88 
• References 5-89 

Scaling Service Provider Networks 6-1 
Scaling IGP and BGP in Service Provider Networks 6-3

• Common Service Provider Network 6-5 
• Route Propagation in Service Provider Networks 6-9 
• Scaling Service Provider Routing Protocols 6-13 
• Scaling Service Provider Addressing 6-16 
• Example 6-17 
• Summary 6-18 
• References 6-18 

Introducing Route Reflectors 6-19

• IBGP Scalability Issues in a Transit AS 6-21
• Route Reflector Split-Horizon Rules 6-23 
• Redundant Route Reflectors 6-26 
• Route Reflector Clusters 6-28 
• Example 6-30 
• Additional Route Reflector Loop Prevention Mechanisms 6-31 
• Summary 6-32 
• References 6-32 
• Next Steps 6-32 

Designing Networks with Route Reflectors 6-33

• Network Design with Route Reflectors 6-35 
• Example 6-37 
• Potential Network Issues 6-38 
• Hierarchical Route Reflectors 6-39 
• Example 6-40 
• Summary 6-41 
• References 6-41 

Configuring and Monitoring Route Reflectors 6-43

• Route Reflector Backbone Migration 6-45
• Configuring Route Reflectors 6-46
• Example 6-48 
• Monitoring Route Reflectors 6-49 
• Summary 6-51 
• References 6-51

Introducing Confederations 6-53 

• IBGP Transit AS Problems 6-55 
• Example 6-56 
• Splitting a Transit AS with BGP Confederations 6-57 
• AS-Path Propagation Within the BGP Confederation 6-58 
• Example 6-59 
• AS-Path Processing in BGP Confederations 6-61 
• Intra-Confederation EBGP Session Properties 6-62 
• Summary 6-64 
• References 6-64 

Configuring and Monitoring Confederations 6-65 

• BGP Confederation Design Rules 6-67 
• Planning BGP Confederations 6-69 
• Configuring BGP Confederations 6-70 
• Example 6-73 
• Monitoring BGP Confederations 6-75 
• Summary 6-79 
• References 6-79 
• Next Steps 6-79 

Optimizing BGP Scalability 7-1 
Improving BGP Convergence 7-3

• BGP Convergence 7-5 
• BGP Processes 7-6 
• CPU Effects of BGP Processes 7-7 
• Example 7-8 
• Improving BGP Convergence 7-9 
• Path MTU Discovery 7-12 
• Increasing Input Queue Depth 7-15 
• BGP Scan Time 7-18 
• BGP Advertisement Interval 7-21 • Summary 7-24 
• References 7-25 

Limiting the Number of Prefixes Received from a BGP Neighbor 7-27 

• Limiting the Number of Routes Received from a Neighbor 7-29 
• Configuring the BGP Maximum-Prefix Function 7-31 
• Monitoring the BGP Maximum-Prefix Function 7-33 
• Example 7-34 
• Summary 7-36 
• References 7-36 
• Next Steps 7-36 

Implementing BGP Peer Groups 7-37 

• Peer Groups as a BGP Performance Tool 7-43
• BGP Peer Group Limitations 7-44 
• BGP Peer Groups in Cisco IOS Software 7-46 
• Configuring Peer Groups 7-47 
• Example 7-49 
• Example 7-50 
• Example 7-51 
• Monitoring Peer Groups 7-52 
• Summary 7-57 
• References 7-58 
• Next Steps 7-58 

Using BGP Route Dampening 7-59 

• BGP Route Dampening 7-61 
• Route-Dampening Operation 7-63 
• Configuring BGP Route Dampening 7-65 
• Releasing Dampened Routes 7-68 
• Monitoring Route Dampening 7-70
• Example 7-71 
• Summary 7-78 
• References 7-78 
• Next Steps 7-78