Lab Objective:
The focus of this lab is to understand BGP implementation and configuration in Cisco IOS routers. Additional technologies include summarization, route filtering and path control.
Lab Topology:
The lab network topology is illustrated below:
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IMPORTANT NOTE If you are using the www.howtonetwork.net racks, please bring up the LAN interfaces connected to the routers by issuing the no shutdown command on the connected switches. If you are using a home lab with no Switches, you can bring up the LAN interfaces using the following configurations on your routers: interface fastethernet 0/0 no keepalive loopback no shutdown Alternately, you can simply connect the interfaces to a hub or switch if you have one available in your own lab. |
Task 1
Configure hostnames and IP addressing on all routers as illustrated in the network topology. Additionally, configure a Loopback 0 interface on all routers using the router number and a host mask. For example, on R1, configure Loopback 0 with the IP address 1.1.1.1/32, on R2 configure interface Loopback 0 with the IP address 2.2.2.2/32 and so forth for R3 and also R4.
Task 2
Configure BGP as illustrated in the topology. Use the Loopback 0 addresses for peering. Do NOT configure any IGPs. Instead, use static routes only. R1 should peer with R2 and R4. R2 should peer with R1 and R3. R3 should peer with R2 and R4. R4 should peer with R1 and R3. On R3 and R4, ensure that packets are load balanced between the two WAN links. Do NOT configure PPP Multilink. Verify the configuration using the appropriate commands.
Task 3
Configure all routers to advertise their LAN subnet addresses via BGP. These should appear in the BGP RIBs of all other routers with an ORIGIN code of INCOMPLETE, by default. Verify the configuration using the appropriate commands.
Task 4
Configure BGP so that R4 prefers the path via R3 to reach any subnet. You are NOT allowed to implement any configuration on R4 itself. Verify your BGP configuration using the appropriate commands.
Task 5
Configure R4 so that it sends all updates to R3 with a MED of 4. Configure R2 so that it sends all updates to R3 with a MED of 2. Ensure that R3 prefers all routes with the better (lower) MED value. Do NOT modify any other BGP attributes or default administrative distance values when completing this task. Verify your configuration using the appropriate commands.
Task 6
Configure the following Loopback interfaces on R2:
Loopback 192: IP Address 192.1.1.1/24 Loopback 193: IP Address 193.1.1.1/24 Loopback 194: IP Address 194.1.1.1/24 Loopback 195: IP Address 195.1.1.1/24
The 192.1.1.1/24 subnet should appear to have originated in AS 192. The 193.1.1.1/24 subnet should appear to have originated in AS 193. The 194.1.1.1/24 subnet should appear to have originated in AS 194. And finally, the 195.1.1.1/24 subnet should appear to have originated in AS 195. These prefixes should be advertised using the network command. Verify your configuration using the appropriate commands.
Task 7
Configure R1 so that it only accepts prefixes originated in AS 192, 193, 194 and 195 from R4. It should never have any entries in its BGP RIB for any prefixes originating in these ASes directly from R2. Use an AS_PATH filter. This should only have TWO lines. Verify your configuration using the appropriate commands.