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Lab 17: Configuring OSPF Demand Circuits over ISDNThis lab assumes an in-depth knowledge of the various routing protocols. It might be a good idea to read Chapter 12 before attempting this lab. Try to complete this lab on your own by doing some research and looking up the necessary commands first before peeking at the solution provided. Refer to the network diagram in Figure 7-12 for reference; call this network the ABC company. Figure 7-12. Network Topology for This Lab
Configure the ABC network so that it satisfies the following requirements:
Lab 17 SolutionExample 7-62 shows the final configuration solution that meets the aforementioned requirements for this lab. Example 7-61 Phoenix 2, Phoenix, Green Bay, San Diego, and Minneapolis Router ConfigurationsPhoenix2# show running-config Building configuration... Current configuration: ! version 11.2 no service password-encryption no service udp-small-servers no service tcp-small-servers ! hostname Phoenix2 ! enable password cisco ! ! interface Ethernet0 ip address 170.10.35.2 255.255.255.0 ! interface Ethernet1 no ip address shutdown ! interface Serial0 no ip address shutdown no fair-queue ! interface Serial1 no ip address shutdown ! router eigrp 1 network 170.10.0.0 no auto-summary ! no ip classless ! ! line con 0 exec-timeout 0 0 privilege level 15 logging synchronous line aux 0 line vty 0 4 password cisco login ! end _______________________________________________________________________ Phoenix# show running-config Building configuration... Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Phoenix ! logging buffered 9096 debugging ! ip subnet-zero isdn switch-type basic-dms100 ! ! ! interface Ethernet0 ip address 170.10.35.1 255.255.255.0 no ip directed-broadcast ! interface Serial0 no ip address no ip directed-broadcast shutdown ! interface Serial1 description POINT TO POINT LINK TO GREEN BAY bandwidth 64 ip address 170.10.23.2 255.255.255.252 no ip directed-broadcast clockrate 125000 ! router eigrp 1 network 170.10.0.0 no auto-summary ! no ip classless ! ! ! line con 0 privilege level 15 logging synchronous transport input none line aux 0 line vty 0 4 login ! end _______________________________________________________________________ Green_Bay# show running-config Building configuration... Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname Green_Bay ! ! username San_Diego password 0 isdnlab ip subnet-zero isdn switch-type basic-dms100 ! ! ! interface Ethernet0 ip address 170.10.22.1 255.255.255.0 no ip directed-broadcast no keepalive ! interface Serial0 no ip address no ip directed-broadcast encapsulation frame-relay logging event subif-link-status logging event dlci-status-change no fair-queue clockrate 125000 ! interface Serial0.1 point-to-point description 56K FRAME RELAY CONNECTION bandwidth 56 ip address 170.10.29.1 255.255.255.252 no ip directed-broadcast frame-relay interface-dlci 300 ! interface Serial1 description POINT TO POINT LINK TO PHOENIX bandwidth 64 ip address 170.10.23.1 255.255.255.252 no ip directed-broadcast ! interface BRI0 ip address 170.10.129.1 255.255.255.252 no ip directed-broadcast encapsulation ppp ip ospf cost 9999 ip ospf demand-circuit dialer callback-secure dialer idle-timeout 300 dialer enable-timeout 5 dialer map ip 170.10.129.2 name San_Diego class isdnlab broadcast 6129319360 dialer-group 1 isdn switch-type basic-dms100 isdn spid1 61293199371111 isdn spid2 61293199381111 isdn caller 6129319360 callback ppp callback accept ppp authentication chap ! router eigrp 1 redistribute ospf 1 metric 64 100 200 10 1500 passive-interface BRI0 passive-interface Serial0.1 network 170.10.0.0 no auto-summary ! router ospf 1 redistribute eigrp 1 metric 100 subnets route-map DENY_BRI_ROUTE network 170.10.29.1 0.0.0.0 area 0 network 170.10.129.1 0.0.0.0 area 0 passive-interface Serial1 ! no ip classless ! ! map-class dialer isdnlab dialer callback-server username access-list 1 permit 170.10.129.0 0.0.0.3 dialer-list 1 protocol ip permit route-map DENY_BRI_ROUTE deny 10 match ip address 1 ! route-map DENY_BRI_ROUTE permit 20 ! ! ! line con 0 privilege level 15 logging synchronous transport input none line aux 0 line vty 0 4 login ! end _______________________________________________________________________ San_Diego# show running-config Building configuration... Current configuration: ! version 11.2 no service password-encryption no service udp-small-servers no service tcp-small-servers ! hostname San_Diego ! enable password cisco ! username Green_Bay password 0 isdnlab ip subnet-zero no ip domain-lookup isdn switch-type basic-dms100 ! interface Ethernet0 no ip address no keepalive media-type 10BaseT ! interface Ethernet1 no ip address media-type 10BaseT ! interface Ethernet2 no ip address shutdown media-type 10BaseT ! interface Ethernet3 no ip address shutdown media-type 10BaseT ! interface Ethernet4 no ip address shutdown media-type 10BaseT ! interface Ethernet5 no ip address shutdown media-type 10BaseT ! interface Serial0 no ip address encapsulation frame-relay ! interface Serial0.1 point-to-point description 56K FRAME RELAY CONNECTION ip address 170.10.29.2 255.255.255.252 bandwidth 56 frame-relay interface-dlci 200 ! interface Serial1 ip address 170.10.49.2 255.255.255.252 clockrate 125000 ! interface Serial2 no ip address shutdown ! interface Serial3 no ip address shutdown ! interface BRI0 ip address 170.10.129.2 255.255.255.252 encapsulation ppp ip ospf cost 9999 ip ospf demand-circuit isdn spid1 61293193601111 isdn spid2 61293197761111 dialer idle-timeout 300 dialer wait-for-carrier-time 10 dialer map ip 170.10.129.1 name Green_Bay broadcast 6129319937 dialer-group 1 no fair-queue ppp callback request ppp authentication chap ! interface BRI1 no ip address shutdown ! interface BRI2 no ip address shutdown ! interface BRI3 no ip address shutdown ! router ospf 1 network 170.10.29.2 0.0.0.0 area 0 network 170.10.129.2 0.0.0.0 area 0 network 170.10.49.2 0.0.0.0 area 1 ! ip classless ! dialer-list 1 protocol ip permit ! line con 0 exec-timeout 0 0 privilege level 15 logging synchronous line aux 0 line vty 0 4 exec-timeout 0 0 privilege level 15 logging synchronous no login ! end _______________________________________________________________________ Minneapolis# show running-config Building configuration... Current configuration: ! version 11.2 no service password-encryption no service udp-small-servers no service tcp-small-servers ! hostname Minneapolis ! enable password cisco ! ! interface Ethernet0 ip address 170.10.44.1 255.255.255.0 no keepalive ! interface Serial0 no ip address shutdown no fair-queue ! interface Serial1 ip address 170.10.49.1 255.255.255.252 ! router ospf 1 network 170.10.0.0 0.0.255.255 area 1 ! no ip classless ! ! line con 0 privilege level 15 logging synchronous line aux 0 line vty 0 4 privilege level 15 password cisco no login ! end Lab 17 Solution DiscussionAgain, nothing special is going on with the Phoenix, Phoenix 2, and Minneapolis configurations. They are being used here only to generate routes. The bulk of the configuration commands needed for this lab are done with the Green Bay router. This lab hinted at the use of OSPF demand circuit, in that it asked the ISDN link to be brought up in the case of a loss of routes over the Frame Relay connection. If the lab had asked you to have the ISDN line come up in case of physical loss of connectivity on the Frame Relay link, using the backup interface option would have been more appropriate. To satisfy requirement 3, Green Bay was set up as a callback router. Requirement 4 asked for authentication using MD5 encryption, so CHAP had to be configured. We also set it up with ISDN caller ID to satisfy requirement 5. Both Green Bay and San Diego have dialer map statements, so both have the capability to issue ISDN calls. Requirement 6 was satisfied with setting the dialer idle-timeout to 300 seconds on both ends of the ISDN connection. The biggest issue with this particular lab is getting the ISDN line to remain quiet when the network is stable. If you were able to do this without first looking at the solution, you should be proud of your accomplishment. The important thing to notice about the Green Bay router configuration is the use of the route map statement when redistributing EIGRP into OSPF. Recall from the OSPF demand circuit section that sometimes you need to do more than simply issue the ip ospf demand-circuit command. This lab network is a classic example of this. When redistributing EIGRP into OSPF on the Green Bay router, you have effectively created a routing loop because the BRI interface (170.10.129.1) also is included with the EIGRP network. Because of this, this interface constantly is being redistributed into OSPF from EIGRP, and vice versa. To fix this, you needed to use a route map to deny the 170.10.129.0/30 network from being redistributed into OSPF. An alternative to using a route map would have been to use a distribute list, denying this network from being redistributed. One other important thing to note is the use of the ip ospf cost 9999 command under the BRI interface of the Green Bay and San Diego routers. Remember that requirement 7 of the lab basically requires you to use the bandwidth 56 command under interface s0.1 of both routers. Because of this, OSPF actually preferred the BRI link because it had a lower cost. This was fixed by increasing the OSPF cost to an artificially high number on the BRI interface. This number didn't have to be this high, but we chose to use 9999 for emphasis. You also could have used the ip ospf cost command on the Serial 0.1 of these routers to decrease the cost. |
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