CertificationZone Page 1 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 Date of Issue: 11-01-1999 Routing Principles and IOS Implementation Lab Scenario by Howard C. Berkowitz Objective A Reality Check Router Configurations PARSLEY's Configuration: THYME's Configuration: SAGE's Configuration: ROSEMARY's Configuration: First Pass Router Configurations PARSLEY's Configuration: THYME's Configuration: SAGE's Configuration: ROSEMARY's Configuration: Analysis TIP The Distance command Objective The existing configuration runs IGRP. Convert the network to run OSPF without using redistribution. Run OSPF and IGRP in parallel at first, continuing the use of IGRP as the active routing protocol, until you verify OSPF operation. Figure 1 shows the initial physical configuration and addressing of the routers. Figure 1 A Reality Check Can you ping and traceroute to all interfaces, including the loopbacks? Why? Why not? CertificationZone Page 2 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 Router Configurations These configurations work with IGRP. PARSLEY's Configuration: parsley#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname parsley ! enable password pass ! ip subnet-zero ! interface Loopback0 ip address 192.168.254.254 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.1 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 ip address 192.168.3.1 255.255.255.252 no fair-queue ! interface Serial1 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.1 255.255.255.0 ring-speed 16 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 network 192.168.3.0 ! ip host thyme 192.168.1.2 ip host sage 192.168.1.3 ip host rosemary 192.168.1.4 ! ! line con 0 exec-timeout 0 0 line aux 0 transport input all line vty 0 4 no login ! end parsley# THYME's Configuration: CertificationZone Page 3 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 thyme#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname thyme ! enable password pass ! ip subnet-zero ! interface Loopback0 ip address 192.168.253.253 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.2 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Ethernet2 no ip address shutdown ! interface Ethernet3 no ip address shutdown ! interface Serial0 ip address 192.168.3.2 255.255.255.252 no fair-queue ! interface Serial1 ip address 192.168.3.5 255.255.255.252 ! interface Serial2 no ip address shutdown ! interface Serial3 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.2 255.255.255.0 ring-speed 16 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 network 192.168.3.0 ! ip host parsley 192.168.1.1 ip host sage 192.168.1.3 ip host rosemary 192.168.1.4 ! ! line con 0 line aux 0 transport input all line vty 0 4 no login ! end thyme# CertificationZone Page 4 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 SAGE's Configuration: sage#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname sage ! enable password pass ! ! interface Loopback0 ip address 192.168.252.252 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.3 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 ip address 192.168.3.6 255.255.255.252 no fair-queue ! interface Serial1 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.3 255.255.255.0 ring-speed 16 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 ! ip host parsley 192.168.1.1 ip host thyme 192.168.1.2 ip host rosemary 192.168.1.4 ! ! line con 0 line aux 0 transport input all line vty 0 4 no login ! end sage# ROSEMARY's Configuration: rosemary#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname rosemary CertificationZone Page 5 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 ! enable password pass ! ! interface Loopback0 ip address 192.168.251.251 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.4 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 no ip address shutdown no fair-queue ! interface Serial1 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.4 255.255.255.0 ring-speed 16 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 ! ip host parsley 192.168.1.1 ip host thyme 192.168.1.2 ip host sage 192.168.1.3 ! ! line con 0 exec-timeout 0 0 line aux 0 transport input all line vty 0 4 no login ! end First Pass Here's a first attempt at the solution, improved by adding a more efficient addressing structure. Does it meet the requirements of the scenario? (see "First Pass Analysis" below.) Router Configurations PARSLEY's Configuration: parsley#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname parsley ! CertificationZone Page 6 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 enable password pass ! ip subnet-zero ! interface Loopback0 ip address 192.168.254.254 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.1 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 ip address 192.168.3.1 255.255.255.252 no fair-queue ! interface Serial1 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.1 255.255.255.0 ring-speed 16 ! router ospf 1 network 192.168.1.1 0.0.0.0 area 0.0.0.1 network 192.168.2.1 0.0.0.0 area 0.0.0.1 network 192.168.3.1 0.0.0.0 area 0.0.0.1 network 192.168.254.254 0.0.0.0 area 0.0.0.1 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 network 192.168.3.0 ! ip host thyme 192.168.1.2 ip host sage 192.168.1.3 ip host rosemary 192.168.1.4 ! ! line con 0 exec-timeout 0 0 line aux 0 transport input all line vty 0 4 no login ! end parsley# THYME's Configuration: thyme#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname thyme ! enable password pass ! ip subnet-zero ! interface Loopback0 CertificationZone Page 7 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 ip address 192.168.253.253 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.2 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Ethernet2 no ip address shutdown ! interface Ethernet3 no ip address shutdown ! interface Serial0 ip address 192.168.3.2 255.255.255.252 no fair-queue ! interface Serial1 ip address 192.168.3.5 255.255.255.252 ! interface Serial2 no ip address shutdown ! interface Serial3 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.2 255.255.255.0 ring-speed 16 ! router ospf 1 network 192.168.1.2 0.0.0.0 area 0.0.0.1 network 192.168.2.2 0.0.0.0 area 0.0.0.1 network 192.168.3.2 0.0.0.0 area 0.0.0.1 network 192.168.3.5 0.0.0.0 area 0.0.0.1 network 192.168.253.253 0.0.0.0 area 0.0.0.1 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 network 192.168.3.0 ! ip host parsley 192.168.1.1 ip host sage 192.168.1.3 ip host rosemary 192.168.1.4 ! ! line con 0 line aux 0 transport input all line vty 0 4 no login ! end thyme# SAGE's Configuration: sage#s ru Building configuration Current configuration: ! version 11.0 CertificationZone Page 8 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 service udp-small-servers service tcp-small-servers ! hostname sage ! enable password pass ! ! interface Loopback0 ip address 192.168.252.252 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.3 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 ip address 192.168.3.6 255.255.255.252 no fair-queue ! interface Serial1 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.3 255.255.255.0 ring-speed 16 ! router ospf 1 network 192.168.1.3 0.0.0.0 area 0.0.0.1 network 192.168.2.3 0.0.0.0 area 0.0.0.1 network 192.168.3.6 0.0.0.0 area 0.0.0.1 network 192.168.252.252 0.0.0.0 area 0.0.0.1 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 ! ip host parsley 192.168.1.1 ip host thyme 192.168.1.2 ip host rosemary 192.168.1.4 ! ! line con 0 line aux 0 transport input all line vty 0 4 no login ! end sage# ROSEMARY's Configuration: rosemary#s ru Building configuration Current configuration: ! version 11.0 service udp-small-servers service tcp-small-servers ! hostname rosemary ! enable password pass ! ! CertificationZone Page 9 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 interface Loopback0 ip address 192.168.251.251 255.255.255.0 ! interface Ethernet0 ip address 192.168.1.4 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 no ip address shutdown no fair-queue ! interface Serial1 no ip address shutdown ! interface TokenRing1 no ip address shutdown ! interface TokenRing0 ip address 192.168.2.4 255.255.255.0 ring-speed 16 ! router ospf 1 network 192.168.1.4 0.0.0.0 area 0.0.0.1 network 192.168.2.4 0.0.0.0 area 0.0.0.1 network 192.168.251.251 0.0.0.0 area 0.0.0.1 ! router igrp 1 network 192.168.1.0 network 192.168.2.0 ! ip host parsley 192.168.1.1 ip host thyme 192.168.1.2 ip host sage 192.168.1.3 ! ! line con 0 exec-timeout 0 0 line aux 0 transport input all line vty 0 4 no login ! end Analysis These configurations do not meet the requirements. You have a mixture of IGRP and OSPF routes in the active routing table, which was not the goal. The goal was to keep IGRP running, verify OSPF was collecting the proper topology, and only then convert to OSPF. What is wrong? This space left blank so that you don't peek at the answer! ;-) CertificationZone Page 10 of 11 http://www.certificationzone.com/studyguides/s /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 The reconfiguration was too ambitious. It attempted simultaneously to introduce a new routing protocol and a new addressing scheme. See the Tutorial "Routing Principles and IOS Implementation Considerations" for a discussion of how routes are chosen for routing table installation. The person writing this first configuration forgot that prefix length the number of one bits in the subnet mask is considered before administrative distance. While he correctly observed that OSPF's administrative distance is higher (i.e., less preferred) than IGRP's, he forgot that the VLSM subnets introduced into the network were more specific, and thus preferable, to any IGRP route. The proper approach to this problem is to change one thing at a time: • Add the OSPF routing protocol • Verify operation • Add distance commands to make OSPF the preferred protocol over IGRP • Change the addressing to VLSM • Add summarization, stubby areas, and other OSPF enhancements (not a requirement for this specific scenario) The Distance command Cisco uses administrative distance to decide which source is "most believable" about a route to a certain destination. Administrative distance breaks ties between routes of the same specificity the same prefix length (i.e., number of one bits in the subnet mask) to a given destination. In the accompanying Tutorial, you will see the default administrative distance that the IOS assigns to each source of routing information. You can override these defaults with the distance subcommand, which you code underneath a router major command. TIP When upgrading both the dynamic routing protocol and the addressing, upgrade the routing protocol first, verify operation, and only then renumber. Keep the network stable during conversion, changing one thing at a time. The Bay RS operating system, which is the equivalent of IOS for Nortel routers and is also the base of Microsoft RRAS, contains a default for OSPF routes that differs from Cisco's but can be quite useful. Since Bay does not support proprietary IGRP, they assumed that any conversions would be from RIP to OSPF. In Bay RS, the OSPF interface costs defaults to 1, rather than the 108/bandwidth used by most vendors, including Cisco. By setting the default to 1, the sum of costs along any path becomes the hop count. At least inside areas, OSPF will select the same paths as would RIP, which simplifies verification that the new protocol is working in the same way as the old. True, summarization at area boundaries, and [...]... of distance changes the administrative distance of all routing information received from a given source: Router rip Redistribute igrp 1 Distance 130 True, summarization at area boundaries, and the use of stubby areas with multiple area border routers, may change the routing with respect to RIP What does that suggest? That, perhaps, summarization and stubby areas should be added once the basic OSPF is... desirable than those routes originated in RIP Does this form of the distance command fit our scenario, which specifies that you should not use redistribution? Router igrp 1 Network 172.17.0.0 Distance 120 172.17.1.1 0.0.0.0 1 Access-list 1 permit 172.16.0.0 0.0.255.255 The second form, shown above, is more appropriate for this scenario In the example, IGRP sets the distance to 120 for all routes received... for all routes received from the advertising router (172.16.2.1) that match access-list 1 In the distance command, the address and wildcard mask in the distance statement refer to the address of the advertising router, not the route itself When using the distance statement with OSPF, the address and wildcard mask will refer to the router id of the originating router For this reason, you should use 0.0.0.0... should be added once the basic OSPF is working? After all, the existing network is working, to some extent, without them Bay does recommend changing the inteface costs to 108/bandwidth once the conversion is complete Summarization and stub areas can be added after the costs are changed The lines above will assign an administrative distance of 130 to all IGRP routes learned by RIP RIP's default administrative . /?Issue=3&IssueDate=11-01-1999&CP= 11/06/01 Date of Issue: 11-01-1999 Routing Principles and IOS Implementation Lab Scenario by Howard C. Berkowitz Objective A Reality. simultaneously to introduce a new routing protocol and a new addressing scheme. See the Tutorial " ;Routing Principles and IOS Implementation Considerations"