Transit AS Routing

1-2 Semester 8 Internetwork Troubleshooting v1.0 - Lab 14.3.3.2 Copyright  2001, Cisco Systems, Inc.
Lab 14.3.3.2: Transit AS Routing
AS200
Fa0/0
10.1.1.2/24
S0/0
DCE
.1
.2 S0/0
Fa0/0
192.168.0.1/24
AS100
ISP1A
SanJose1
10.0.0.0/30
ISP1B
Fa0/0
10.1.1.1/24
IBGP
EBGP

Objective
Successful propagation of customer routes through IBGP.
Scenario
You are a network administrator for an ISP with autonomous system
number 200. Your autonomous system is multi-homed to various
customers including AS 100 for the International Travel Agency (ITA).
Routers running IBGP within AS 200 cannot reach AS 100.
Step 1
Cable the lab as shown in the diagram.

Load the configuration files into your routers.

2-2 Semester 8 Internetwork Troubleshooting v1.0 - Lab 14.3.3.2 Copyright  2001, Cisco Systems, Inc.
Step 2
Start the investigation on router ISP1B with show ip bgp, show ip
route and show ip bgp 10.1.1.2; record results below:



Step 3
Based on the output and your knowledge of BGP, what are some possible
causes for routers from other autonomous systems cannot reach AS 100?



Step 4
What is your action plan for allowing traffic originating in or transiting AS 200
to reach AS 100?



Step 5
Implement your action plan and observe results with show ip bgp, show
ip route and show ip bgp 10.1.1.2. Also, ensure connectivity with
a ping from router ISP1B to the remote LAN in AS 100.

Step 6
Document summary of problem, troubleshooting methods and resolution.