© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-1 Implementing a Scalable Multiarea Network OSPF- Based Solution Lab 3-2 Debrief

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-2 Lab Topology

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-3 Lab Review: What Did You Accomplish?  Task 1: Configuring OSPF backbone area –What steps did you take to configure the OSPF routing protocol on a router belonging to the backbone area?  Task 2: Configuring OSPF nonbackbone areas –What steps did you take to configure the OSPF routing protocol on routers belonging to different nonbackbone areas?  Task 3: Tuning an OSPF operation –How can the default cost calculation be changed? –How can the router ID be changed? –How can you preserve CPU cycles on router R3 by eliminating the unnecessary OSPF traffic on a LAN segment?

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-4 Verification  Did you have enough information to create an implementation plan?  Is adjacency in area 0 between routers R1 and BBR2 established?  Is the IP routing table populated with correct OSPF routes?  Is adjacency established between the routers of nonbackbone areas?  Is the IP routing table populated with the correct OSPF routes?  How is a change in cost calculation done?  What is the router ID of router R1?  Is the IP routing table populated with the correct OSPF routes?  Did router R3 stop trying to set up an OSPF adjacency via the LAN segment?

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-5 Checkpoints  Configure OSPF in area 0.  Check for adjacencies in area 0 between routers R1 and BBR2.  Check the IP routing table for the proper OSPF routes.  Configure OSPF in nonbackbone areas  Check if an adjacency is established between the routers of nonbackbone areas.  Check the IP routing table for proper OSPF routes.  Change the cost calculation.  Manipulate the OSPF router ID of router R1.  Check the IP routing table for the proper OSPF routes.  Check that router R3 stopped trying to set up an OSPF adjacency via the LAN segment.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-6 Sample Solution  Configure OSPF for backbone and nonbackbone areas.  Select the correct OSPF network type for each WAN segment.  Change the default cost calculation to manipulate the path selection and change the router ID to manipulate DR and BDR selection.  Configure the passive interface to suppress routing traffic and preserve CPU cycles on router R3.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-7 Alternative Solutions  You can design different backbone and nonbackbone areas, for which nonbackbone areas can be non-standard in order to reduce the number of routing updates.  You can configure a different IP adress on the loopback interface to manipulate the router ID.  Because changing the routing protocol is not a realistic solution, you can configure static and default routes.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-8 Q and A  What is the purpose of backbone and nonbackbone areas?  How can a default cost calculation be changed?  Why is the router ID important?  How does a passive interface work in an OSPF routing protocol?

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-9 Summary  Configure OSPF for a backbone area.  Configure OSPF for a nonbackbone area.  Tune OSPF operation by changing how default cost calculation is performed; you can change the cost calculation by changing the router ID and configuring a passive interface. Doing this preserves CPU cycles by eliminating unnecessary OSPF traffic on the LAN segment.

© 2009 Cisco Systems, Inc. All rights reserved. ROUTE v1.0—3-10