Maipu Administration Guide

Configure OSPF External Route Summary

Network Requirements

Run OSPF between Device1 and Device2, and run RIPv2 between Device2 and Device3.
Device2 redistributes RIP routes to OSPF. To decrease the number of routes on Device1, summarize the redistributed RIP routes into summary route 20.0.0.0/16.

Network Topology

Networking for Configuring OSPF External Route Summary

Figure 7-5 Networking for Configuring OSPF External Route Summary

Configuration Steps

Step 1: Create VLANs, and add ports to the required VLANs. (Omitted)

Step 2: Configure IP addresses for the ports. (Omitted)

Step 3: Configure OSPF and RIPv2.

#Configure OSPF for Device1.

Device1#configure terminal
Device1(config)#router ospf 100
Device1(config-ospf)#router-id 1.1.1.1
Device1(config-ospf)#network 10.0.0.0 0.0.0.255 area 0
Device1(config-ospf)#exit

#Configure OSPF and RIPv2 for Device2.

Device2#configure terminal
Device2(config)#router ospf 100
Device2(config-ospf)#router-id 2.2.2.2
Device2(config-ospf)#network 10.0.0.0 0.0.0.255 area 0
Device2(config-ospf)#exit
Device2(config)#router rip
Device2(config-rip)#version 2
Device2(config-rip)#network 20.0.0.0
Device2(config-rip)#exit

#Configure RIPv2 for Device3.

Device3#configure terminal
Device3(config)#router rip
Device3(config-rip)#version 2
Device3(config-rip)#network 20.0.0.0
Device3(config-rip)#exit

#Query the routing table of Device2.

Device2#show ip route  
Codes: C - connected, S - static, R - RIP, O - OSPF, OE-OSPF External, M - Management 
       D - Redirect, E - IRMP, EX - IRMP external, o - SNSP, B - BGP, i-ISIS  
 
Gateway of last resort is not set 
 
C 10.0.0.0/24 is directly connected, 00:15:46, vlan2 
C 20.0.1.0/24 is directly connected, 00:15:23, vlan3
R 20.0.2.0/24 [120/1] via 20.0.1.2, 00:12:17, vlan3
R 20.0.3.0/24 [120/1] via 20.0.1.2, 00:12:06, vlan3
C 127.0.0.0/8 is directly connected, 03:34:27, lo0

Step 4: Configure OSPF to redistribute RIP routes.

#Configure Device2.

Device2(config)#router ospf 100
Device2(config-ospf)#redistribute rip
Device2(config-ospf)#exit

#Query OSPF LSDB of Device2.

Device2#show ip ospf database  
 
            OSPF Router with ID (2.2.2.2) (Process ID 100) 
 
                Router Link States (Area 0) 
 
Link ID    ADV Router   Age   Seq#        CkSum   Link count
1.1.1.1	   1.1.1.1      1071  0x80000003  0x729f  1  
2.2.2.2    2.2.2.2      873   0x80000004  0x38cd  1  
 
                Net Link States (Area 0) 
 
Link ID    ADV Router   Age   Seq#        CkSum
10.0.0.2   2.2.2.2      1070  0x80000001  0x43d6  
 
                AS External Link States  
 
Link ID    ADV Router   Age   Seq#        CkSum    Route 
20.0.1.0   2.2.2.2      365   0x80000001  0x7d04   E2 20.0.1.0/24 [0x0]  
20.0.2.0   2.2.2.2      365   0x80000001  0x720e   E2 20.0.2.0/24 [0x0]  
20.0.3.0   2.2.2.2      365   0x80000001  0x6718   E2 20.0.3.0/24 [0x0]

According to the OSPF database, three external LSA have been generated, indicating that the RIP routes have been redistributed to OSPF.

#Query the routing table of Device1.

Device1#show ip route  
Codes: C - connected, S - static, R - RIP, O - OSPF, OE-OSPF External, M Management 
       D - Redirect, E - IRMP, EX - IRMP external, o - SNSP, B BGP, i-ISIS  
 
Gateway of last resort is not set 
 
C  10.0.0.0/24 is directly connected, 00:56:40, vlan2
OE 20.0.1.0/24 [150/20] via 10.0.0.2, 00:02:40, vlan2
OE 20.0.2.0/24 [150/20] via 10.0.0.2, 00:02:40, vlan2
OE 20.0.3.0/24 [150/20] via 10.0.0.2, 00:02:40, vlan2
C  127.0.0.0/8 is directly connected, 115:12:28, lo0

Device1 has learnt redistributed RIP routes.

Step 5: On the ASBR, configure OSPF external route summary. Now Device2 is the ASBR.

#Configure Device2 and summarize the redistributed RIP routes into 20.0.0.0/16.

Device2(config)#router ospf 100
Device2(config-ospf)#summary-address 20.0.0.0 255.255.0.0
Device2(config-ospf)#exit

Step 6: Check the result.