2.5.3 Packet Tracer - Propagate a Default Route in OSPFv2 (Instructor Version)
2.5.3 Packet Tracer – Propagate a Default Route in OSPFv2
Instructor Note: Red font color or gray highlights indicate text that appears in the instructor copy only.
Addressing Table
| Device | Interface | IPv4 Address | Subnet Mask | Default Gateway |
|---|---|---|---|---|
| R1 | G0/0 | 172.16.1.1 | 255.255.255.0 | N/A |
| S0/0/0 | 172.16.3.1 | 255.255.255.252 | ||
| S0/0/1 | 192.168.10.5 | 255.255.255.252 | ||
| R2 | G0/0 | 172.16.2.1 | 255.255.255.0 | N/A |
| S0/0/0 | 172.16.3.2 | 255.255.255.252 | ||
| S0/0/1 | 192.168.10.9 | 255.255.255.252 | ||
| S0/1/0 | 209.165.200.225 | 255.255.255.224 | ||
| R3 | G0/0 | 192.168.1.1 | 255.255.255.0 | N/A |
| S0/0/0 | 192.168.10.6 | 255.255.255.252 | ||
| S0/0/1 | 192.168.10.10 | 255.255.255.252 | ||
| PC1 | NIC | 172.16.1.2 | 255.255.255.0 | 172.16.1.1 |
| PC2 | NIC | 172.16.2.2 | 255.255.255.0 | 172.16.2.1 |
| PC3 | NIC | 192.168.1.2 | 255.255.255.0 | 192.168.1.1 |
| Web Server | NIC | 64.100.1.2 | 255.255.255.0 | 64.100.1.1 |
Objectives
- Part 1: Propagate a Default Route
- Part 2: Verify Connectivity
Background
In this activity, you will configure an IPv4 default route to the Internet and propagate that default route to other OSPF routers. You will then verify the default route is in downstream routing tables and that hosts can now access a web server on the Internet.
Instructions
Part 1: Propagate a Default Route
Step 1: Test connectivity to the Web Server
a. From PC1, PC2, and PC3, attempt to ping the Web Server IP address, 64.100.1.2.
Were any of the pings successful?
No.
What message did you receive, and which device issued the message?
Destination unreachable from R2.
b. Examine the routing tables on routers R1, R2, and R3.
What statement is present in the routing tables that indicates that the pings to the Web Server will fail?
Gateway of last resort is not set
Step 2: Configure a default route on R2.
Configure R2 with a directly attached default route to the Internet.
R2(config)# ip route 0.0.0.0 0.0.0.0 Serial0/1/0
Note: Router will give a warning that if this interface is not a point-to-point connection, it may impact performance. You can ignore this warning because it is a point-to-point connection.
Step 3: Propagate the route in OSPF.
Configure OSPF to propagate the default route in OSPF routing updates.
R2(config)# router ospf 1 R2(config-router)# default-information originate
Step 4: Examine the routing tables on R1 and R3.
Examine the routing tables of R1 and R3 to verify that the route has been propagated.
R1> show ip route <output omitted> Gateway of last resort is 172.16.3.2 to network 0.0.0.0 <output omitted> O*E2 0.0.0.0/0 [110/1] via 172.16.3.2, 00:00:08, Serial0/0/0 !------------------- R3> show ip route <output omitted> Gateway of last resort is 192.168.10.9 to network 0.0.0.0 <output omitted> O*E2 0.0.0.0/0 [110/1] via 192.168.10.9, 00:08:15, Serial0/0/1
Part 2: Verify Connectivity
Verify that PC1, PC2, and PC3 can ping the web server.
Device Configs - Final
Router R2
! ============================================================== !--- 2.5.3 Packet Tracer - Propagate a Default Route in OSPFv2 !--- ANSWER SCRIPT FOR ROUTER R2 !--- Usage: from the console (or a Telnet/SSH session, if already reachable) on R2, enter privileged EXEC mode with "enable", then paste this whole file. Every line beginning with "!" is a comment; IOS ignores it, so pasting a comment by accident is harmless. !--- OSPF (process 1) is already configured and converged on R1/R2/R3; only R2 touches the Internet cloud via S0/1/0. This script adds a static default route out that interface, then redistributes it into OSPF as an external (E2) route so R1 and R3 learn it automatically - no changes are needed on R1 or R3. ! ============================================================== enable configure terminal ! -------------------------------------------------------------- !--- Part 1, Step 2: Configure a default route toward the Internet ! -------------------------------------------------------------- !--- Points at the interface rather than a next-hop IP since this is a point-to-point serial link to the Internet cloud; IOS will warn about this on a non-point-to-point interface, but that warning does not apply here. ip route 0.0.0.0 0.0.0.0 Serial0/1/0 ! -------------------------------------------------------------- !--- Part 1, Step 3: Propagate the default route into OSPF ! -------------------------------------------------------------- !--- Without this, the static default route above stays local to R2 and never reaches R1/R3's routing tables. router ospf 1 default-information originate end ! ============================================================== !--- Verification (from R1, R3, and the PCs): !--- R1> show ip route -> "Gateway of last resort is 172.16.3.2 to network 0.0.0.0", O*E2 0.0.0.0/0 via Serial0/0/0 !--- R3> show ip route -> "Gateway of last resort is 192.168.10.9 to network 0.0.0.0", O*E2 0.0.0.0/0 via Serial0/0/1 !--- PC1, PC2, PC3 -> ping 64.100.1.2 (Web Server) should now succeed ! ==============================================================
