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Introduction to BGP

Chapter Description

In this sample chapter from Routing TCP/IP, Volume II: CCIE Professional Development, 2nd Edition, author Jeff Doyle covers the basic operation of BGP, including its message types, how the messages are used, and the format of the messages. You also learn about the various basic attributes BGP can associate with a route and how it uses these attributes to choose a best path. Finally, this chapter shows you how to configure and troubleshoot BGP peering sessions.

Configuration Exercises

Table 2-7 lists the autonomous systems, routers, interfaces, and addresses used in Exercises 1 through 4. All interfaces of the routers are shown; physical interfaces may be changed for your solutions to fit your available resources. For each exercise, if the table indicates that the router has a loopback interface, that interface should be the source of all IBGP connections. EBGP connections should always be between physical interface addresses, unless otherwise specified in an exercise. Neighbor descriptions will always be configured to be the router names.

Table 2-7 Details for Configuration Exercises 1–4

AS

Router

Interface

IP Address/Mask

1

R1

G2/0

10.0.0.1/30

G3/0

10.0.0.5/30

S1/0

172.16.0.1/30

Lo0

192.168.0.1/32

 

R2

G2/0

10.0.0.2/30

G3/0

10.0.0.9/30

S1/0

172.16.0.5/30

S1/1

172.16.0.9/30

Lo0

192.168.0.2/32

 

R3

G2/0

172.16.0.10/30

G3/0

172.16.0.6/30

S1/0

fc00::1/64

2

R4

Lo0

192.168.0.3/32

S1/0

172.16.0.2/30

Lo0

192.168.0.4/32

3

R5

Lo1

192.168.0.41/32

S1/0

fc00::2/64

4

R6

Lo0

192.168.0.5/32

S1/0

172.16.0.6/30

S1/1

172.16.0.10/30

Lo0

192.168.0.6/32

  1. Configure OSPF as the IGP for AS1. OSPF area 0 spans the whole AS. AS1 internal routes should not be advertised outside the AS. All point-to-point links over which EBGP is run should not be advertised into the AS. Then configure the IBGP full mesh for AS1. All IBGP connections will be MD5 authenticated using password Ch2_ExcerSizE1.

  2. Configure an EBGP peering between R1 in AS1 and R4 in AS2. Authenticate the EBGP peering using password Ch2_ExcerSizE2. Set the router-id of R4 manually to be the IP address of Loopback 1. In addition, make sure both routers are secured against remote attacks that are based on manipulating TTL values.

  3. Configure EBGP peering between R3 in AS1 and R5 in AS3 using the IPv6 point-to-point physical addresses configured on the routers. Make sure you configure both routers to log all neighbor state changes.

  4. Configure EBGP peering between R2 in AS1 and R6 in AS4 such that load balancing is achieved over both physical links. Do not use link aggregation. Use static routing on R2 and R6.

7. Troubleshooting Exercises | Next Section Previous Section

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