CertificationZone Page 1 of 3 http://www.certificationzone.com/studyguides /?Issue=38&IssueDate=06-01-2001&CP= 11/06/01 Date of Issue: 06-01-2001 OSPF Lab Scenario 1 - Classless and Discontiguous Networks by Howard Berkowitz Setup Initial Configuration OSPF Configuration Requirement Solution Example Configurations Ginger Oregano Soy Garlic Sesame Setup Configure a set of five routers as shown above. All routers are to be in area 0.0.0.1. The yellow/solid medium needs to be broadcast multiaccess. While it is shown as Ethernet, you may use any LAN technology available on your routers. The blue/dotted networks are point-to-point, so they can use any medium available on your routers. The red/parallel line network is intended to be a stub network, so it can be defined on any medium or on a loopback. If you define it on a loopback, be sure to use the specified prefix length. Are there discontiguous networks or overlapping network ranges? Are they a problem? Why or why not? Fix them if they are a problem. Initial Configuration Establish unique router IDs for each router, putting them on loopback interfaces. Do not yet configure OSPF. Verify addresses and the formation of loopback addresses. CertificationZone Page 2 of 3 http://www.certificationzone.com/studyguides /?Issue=38&IssueDate=06-01-2001&CP= 11/06/01 OSPF Configuration Requirement On each router, create an OSPF process that puts each interface into area 0.0.0.1. I strongly recommend that you have one network statement for each interface, but you can experiment with wildcards that put more than one interface into OSPF. It is your choice whether to advertise the loopback subnets. You may choose to enable OSPF debugging and watch the activity as OSPF initializes. With increasing numbers of routers, you will have more and more debug traffic you have been warned! Simply record the traffic for later analysis; it will go by too fast to review on the screen. Troubleshoot any connectivity problems. Observe the routing table that is built. Compare its entries to the general information shown in show ip ospf database, and then to the more detailed information shown with the net and router keywords added to this command. Experiment with the other OSPF display commands, remembering that many of them apply only to multi- area domains. Solution You should have no problem with either discontiguous networks or overlapping ranges. OSPF isn't even aware of classful networks, so discontiguous networks are a non-issue. As long as you configure ip subnet-zero and follow strict CIDR/VLSM-style guidelines for "subnetting a subnet," you should have no problem with overlapping ranges as long as the same host address is not configured in more than one subnet. The overlapping subnets will be distinguished in the routing table by their different masks. Example Configurations Ginger hostname ginger int loop 0 ip addr 192.168.255.1 255.255.255.0 int loop 1 ip addr 10.99.99.101 255.255.0.0 int e0 ip addr 172.17.1.1 255.255.255.0 router ospf 1 network 192.168.255.1 0.0.0.0 area 0.0.0.1 network 10.99.99.101 0.0.0.0 area 0.0.0.1 network 172.17.1.1 0.0.0.0 area 0.0.0.1 Oregano hostname oregano int loop 0 ip addr 192.168.254.1 255.255.255.0 int e0 ip addr 172.17.1.2 255.255.255.0 int s0 ip addr 172.16.1.1 255.255.255.252 router ospf 1 network 192.168.254.1 0.0.0.0 area 0.0.0.1 network 172.17.1.2 0.0.0.0 area 0.0.0.1 network 172.16.1.1 0.0.0.0 area 0.0.0.1 Soy CertificationZone Page 3 of 3 http://www.certificationzone.com/studyguides /?Issue=38&IssueDate=06-01-2001&CP= 11/06/01 hostname soy int loop 0 ip addr 192.168.253.1 255.255.255.0 int e0 ip addr 172.17.1.3 255.255.255.0 int loop 1 ip addr 172.16.2.1 255.255.255.0 router ospf 1 network 192.168.253.1 0.0.0.0 area 0.0.0.1 network 172.17.1.3 0.0.0.0 area 0.0.0.1 network 172.16.2.1 0.0.0.0 area 0.0.0.1 Garlic hostname garlic int loop 0 ip addr 192.168.252.1 255.255.255.0 int e0 ip addr 172.17.1.17 255.255.255.240 int s0 ip addr 172.16.1.2 255.255.255.252 router ospf 1 network 192.168.252.1 0.0.0.0 area 0.0.0.1 network 172.17.1.17 0.0.0.0 area 0.0.0.1 network 172.16.1.2 0.0.0.0 area 0.0.0.1 Sesame hostname sesame int loop 0 ip addr 192.168.251.1 255.255.255.0 int e0 ip addr 172.17.1.4 255.255.255.0 int e1 ip addr 172.17.1.18 255.255.255.240 router ospf 1 network 192.168.251.1 0.0.0.0 area 0.0.0.1 network 172.17.1.4 0.0.0.0 area 0.0.0.1 network 172.17.1.18 0.0.0.0 area 0.0.0.1 [IE-OSPF1-LS1-F03] [2001-05-30-02] Copyright © 2001 Genium Publishing Corporation . area 0.0.0 .1 network 17 2 .17 .1. 4 0.0.0.0 area 0.0.0 .1 network 17 2 .17 .1. 18 0.0.0.0 area 0.0.0 .1 [IE -OSPF1 -LS1-F03] [20 0 1- 0 5-3 0-0 2] Copyright © 20 01 Genium. addr 19 2 .16 8.2 51. 1 255.255.255.0 int e0 ip addr 17 2 .17 .1. 4 255.255.255.0 int e1 ip addr 17 2 .17 .1. 18 255.255.255.240 router ospf 1 network 19 2 .16 8.2 51. 1 0.0.0.0