642-661 BGP

Border gateway protocol

Exam Description

The 642-661 Configuring BGP on Cisco Routers (BGP) exam is a qualifying exam for the Cisco Certified Internetwork Professional certification. The 642-661 BGP exam tests material covered under the Configuring BGP on Cisco Routers (BGP) v 3.1 courses. The BGP exam assesses a candidate's understanding of the theory of BGP, ability to configure BGP on Cisco IOS routers, and skills with troubleshooting on BGP. As a routing protocol, BGP is one of the underlying foundations of the Internet and new-world technologies.

Exam Topics

The following information provides general guidelines for the content likely to be included on the BGP exam. However, other related topics may also appear on any specific delivery of the exam.

I. BGP Overview

Introduction to BGP

• Given a network scenario, identify appropriate BGP usage and its limitations
• Given a typical BGP network scenario, describe the concept of BGP neighbors and the neighbor session establishment procedures 
• Given a diagram of an operational BGP network, describe interdomain route processing, route propagation and BGP path selection 
• Given a network consisting of multiple domains, successfully configure BGP
• Given a configured BGP network, verify proper operation and perform the steps necessary to correct basic BGP configuration errors

II. Route Selection Using Policy Controls

Multi-Homed BGP Networks

• Given a customer scenario where connections to multiple ISPs must be supported, describe the need for influencing BGP route selection

AS-Path Filters

Prefix-List Filters

Outbound Route Filtering

Route-Maps as BGP Filters 

Implementing Changes in BGP Policy

III. Route Selection Using Attributes

BGP Path Attributes

• List BGP path attributes and functionality of each attribute Influencing BGP Route Selection with Weights
• Given a customer scenario where multiple connections must be supported, successfully configure BGP to influence route selection using the weight attribute

BGP Local Preference

• Given a customer scenario where multiple connections must be supported, successfully configure BGP to influence route selection using the local preference attribute

BGP Multi-Exit-Discriminator (MED)

• Given a customer scenario where multiple connections must be supported, successfully configure BGP to influence route selection using the Multi-Exit-Discriminator (MED) attribute

BGP Communities

• Given a customer scenario where multiple connections must be supported, successfully configure BGP to influence route selection using BGP community attributes

IV. Customer-to-Provider Connectivity with BGP

• Describe the requirements to connect customer networks to the Internet in a service provider environment
• Given a service provider network, implement customer connectivity using static routing
• Given a customer scenario where multiple connections to a single ISP must be supported, implement customer connectivity with BGP
• Given a customer scenario where connections to multiple ISPs must be supported, implement customer connectivity with BGP

V. BGP Transit Autonomous System

• Describe the function of a transit autonomous system and the need for IBGP IBGP and EBGP Interaction in a Transit AS
• Given a transit autonomous system, describe the interaction between EBGP and IBGP in relation to relevant BGP attributes
• Describe the function of an IGP in forwarding packets through an autonomous system
• Given a BGP network scenario, successfully configure an autonomous system to act as a transit backbone
• Given a configured BGP transit network, verify proper operation and perform the steps necessary to correct basic IBGP configuration errors

VI. BGP Route Reflectors

Introduction to Route Reflectors

• Describe the function and operation of route reflectors in a BGP environment
• Based upon established route reflector design rules, describe the concept of hierarchial route reflectors and their requirements
• Given an existing IBGP network, configure and verify proper operation of route reflectors to modify IBGGP split-horizon rules

VII. Advanced BGP Configuration

• Given a typical BGP network, successfully configure BGP to limit the number of prefixes received from a neighbor
• Given a typical service provider network with connections to multiple autonomous systems, use AS-Path prepending to influence the return path selected by the neighboring autonomous systems
• Given a typical BGP network, use BGP peer groups to share common configuration parameters between multiple BGP peers
• Given a properly configured BGP network, use route flap dampening to minimize the impact of unstable routes

VIII. Scaling IGP and BGP in Service Provider Networks

• Describe common routing concerns of service provider networks
• Describe the scalability issues of using OSPF and IS-IS as interior gateway protocols in a service provider network and list solutions for each
• Describe common scalability issues when using BGP in a service provider network and list solutions for each