Tuning OSPF

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Lab 22: EIGRP Route Redistribution, Summarization, and Stub Routing ”Part II

Lab Walkthrough

Configure the Frame Relay switch and attach the four routers in a back-to-back manner to the Frame Relay switch. Use V.35 cables or CSU/DSUs with crossover cables, to connect the routers. Create the four LANs by using switches or hubs/MAUs, as illustrated in Figure 11-13.

When the physical connections are complete, assign IP addresses to all LAN and WAN interfaces, as depicted in Figure 11-13. Be sure that you can ping each router's local LAN and WAN interface before moving on. The wisconsin router will need subinterfaces; one will be a multipoint interface and one will be a point-to-point interface. You will use frame-relay map statements on the multipoint interface. You will use frame-relay interface-dlci commands on the point-to-point interface between the wisconsin and minnesota routers. For full IP connectivity, you will need an additional frame-relay map statement on ohio and georgia pointing toward each other. Example 11-32 lists the Frame Relay configuration, to this point, on all routers involved.

Example 11-32 Frame Relay Configuration on wisconsin, georgia, ohio, and minnesota Routers
  !   hostname wisconsin   !  <<<text omitted>>>  !   interface Serial0   no ip address   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay lmi-type cisco   !   interface Serial0.1 multipoint   ip address 192.168.1.1 255.255.255.248   no ip directed-broadcast   frame-relay map ip 192.168.1.2 121 broadcast   frame-relay map ip 192.168.1.3 150 broadcast   !   interface Serial0.2 point-to-point   ip address 192.168.2.1 255.255.255.0   no ip directed-broadcast   frame-relay interface-dlci 111  _______________________________________________________________________  !   hostname georgia   !  <<<text omitted>>>  !   interface Serial0   ip address 192.168.1.2 255.255.255.248   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay map ip 192.168.1.1 102 broadcast   frame-relay map ip 192.168.1.3 102 broadcast   frame-relay lmi-type cisco   !  _______________________________________________________________________  hostname ohio   !   enable password cisco   !  <<<text omitted>>>  !   interface Serial0   ip address 192.168.1.3 255.255.255.248   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay map ip 192.168.1.1 151 broadcast   frame-relay map ip 192.168.1.2 151 broadcast   frame-relay lmi-type cisco   !  _______________________________________________________________________  hostname minnesota   !  <<<text omitted>>>  !   interface Serial0   ip address 192.168.2.2 255.255.255.0   encapsulation frame-relay   no ip mroute-cache   frame-relay interface-dlci 110  

After local WAN and LAN connectivity has been established, the network configuration will be divided into two parts . First, you will configure the EIGRP domain and then you will integrate RIP.

The basic EIGRP configuration will be similar on all the routers. Following the three-step process, begin by enabling EIGRP on all the routers using the router eigrp 65001 command. The second step is to define the networks to run EIGRP on. The wisconsin, georgia, and ohio routers will route EIGRP on the major networks of 172.16.0.0 and 192.168.1.0.

Therefore, use these networks for your network statements. The wisconsin and minnesota routers will run EIGRP on 192.168.2.0 in addition to 172.16.0.0. Because this is a Frame Relay network, it's a good idea to set the bandwidth statements. Set the bandwidth to 128 kbps on the wisconsin interface s0.1 to accommodate the two 64-kbps PVCs. The georgia and ohio routers should have the bandwidth set to 64 kbps on the Frame Relay interfaces. The default bandwidth is 1.544 Mbps (T1 speed), so there is no need to modify it on the S0.2 interface on the wisconsin router. Example 11-33 lists the configuration of the wisconsin router to this point.

Example 11-33 Configuration of the wisconsin Router
  hostname wisconsin   !   interface Ethernet0   ip address 172.16.5.1 255.255.255.128   no ip directed-broadcast   !   interface Serial0   no ip address   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay lmi-type cisco   !   interface Serial0.1 multipoint   bandwidth 128   ip address 192.168.1.1 255.255.255.248   no ip directed-broadcast   frame-relay map ip 192.168.1.2 121 broadcast   frame-relay map ip 192.168.1.3 150 broadcast   !   interface Serial0.2 point-to-point   ip address 192.168.2.1 255.255.255.0   no ip directed-broadcast   frame-relay interface-dlci 111   !   router eigrp 65001   network 172.16.0.0   network 192.168.1.0   network 192.168.2.0   !  

At first glance, it might appear that routing is working. After all, you have a route table and three EIGRP neighbors on the wisconsin router. But some EIGRP defaults must be disabled to make the network route properly. Notice in Example 11-34 that EIGRP has three neighbors in the route table. Unfortunately, the router also has injected a couple routes to null in its forwarding table.

Example 11-34 show ip route and show ip eigrp neighbors Command Output on the wisconsin Router
 wisconsin#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        * - candidate default, U - per-user static route, o - ODR        P - periodic downloaded static route Gateway of last resort is not set      172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks C       172.16.5.0/25 is directly connected, Ethernet0 D       172.16.0.0/16 is a summary, 00:10:58, Null0      192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks D       192.168.1.0/24 is a summary, 00:11:33, Null0 C       192.168.1.0/29 is directly connected, Serial0.1 C    192.168.2.0/24 is directly connected, Serial0.2 wisconsin# wisconsin#  show ip eigrp neighbors  IP-EIGRP neighbors for process 65001 H   Address                 Interface   Hold Uptime   SRTT   RTO  Q  Seq Type                                         (sec)         (ms)       Cnt Num 2   192.168.1.2             Se0.1        171 00:14:00  768  4608  0  4 1   192.168.1.3             Se0.1        152 00:14:11 1544  5000  0  4 0   192.168.2.2             Se0.2        157 00:14:22    0  3000  0  11 wisconsin# 

If you try to ping any routers in the 172.16.0.0 domain, it will fail. This is because the router is forwarding those packets to its null interface.

You need to correct two problems:

  • The network has discontinuous subnets at the major bit boundaries. The major network 172.16.0.0/16 is divided by the networks 192.168.1.0/29 and 192.168.2.0/24. To correct this problem, disable EIGRP autosummarization on all routers in the internetwork with the no auto-summary EIGRP router command.

  • Split horizon must be corrected, although this problem won't manifest itself until autosummarization is disabled.

Example 11-35 lists the route table of the wisconsin router now that autosummarization is disabled throughout the network. Notice that the 172.16.2.0/24, 172.16.3.0/24, and 172.16.5.0/24 routes are now in the forwarding table.

Example 11-35 show ip route Command Output on the wisconsin Router
 wisconsin#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        * - candidate default, U - per-user static route, o - ODR        P - periodic downloaded static route Gateway of last resort is not set      172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks C       172.16.5.0/25 is directly connected, Ethernet0 D       172.16.6.0/24 [90/20537600] via 192.168.1.2, 00:01:47, Serial0.1 D       172.16.2.0/24 [90/40537600] via 192.168.2.2, 00:54:38, Serial0.2 D       172.16.3.0/24 [90/20528128] via 192.168.1.3, 00:08:32, Serial0.1      192.168.1.0/29 is subnetted, 1 subnets C       192.168.1.0 is directly connected, Serial0.1 C    192.168.2.0/24 is directly connected, Serial0.2 wisconsin# 

As mentioned previously, the other problem that you need to remedy is split horizon. If you test IP connectivity from strictly the wisconsin router, everything would appear normal. However, upon examining the forwarding table of the georgia and ohio routers, you will see that the georgia router does not have the 172.16.3.0/24 subnet. The ohio router also does not have the 172.16.6.0/24 subnet, as shown in Example 11-36.

Example 11-36 show ip route Command Output on the ohio and georgia Routers
 ohio#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        * - candidate default, U - per-user static route, o - ODR        P - periodic downloaded static route Gateway of last resort is not set      172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks D       172.16.5.0/25 [90/40537600] via 192.168.1.1, 00:00:52, Serial0 D       172.16.2.0/24 [90/41049600] via 192.168.1.1, 00:00:52, Serial0 C       172.16.3.0/24 is directly connected, TokenRing0      192.168.1.0/29 is subnetted, 1 subnets C       192.168.1.0 is directly connected, Serial0 D    192.168.2.0/24 [90/41024000] via 192.168.1.1, 00:00:53, Serial0 ohio# _______________________________________________________________________ georgia#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        * - candidate default, U - per-user static route, o - ODR        P - periodic downloaded static route Gateway of last resort is not set      172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks D       172.16.5.0/25 [90/40537600] via 192.168.1.1, 00:01:21, Serial0 C       172.16.6.0/24 is directly connected, Ethernet0 D       172.16.2.0/24 [90/41049600] via 192.168.1.1, 00:01:21, Serial0      192.168.1.0/29 is subnetted, 1 subnets C       192.168.1.0 is directly connected, Serial0 D    192.168.2.0/24 [90/41024000] via 192.168.1.1, 00:01:21, Serial0 georgia# 

These routes are not being propagated because of EIGRP split horizon. This can be verified with the debug ip eigrp packets command. To allow updates to flow properly across a multipoint network, disable split horizon on that interface with the no ip split-horizon eigrp command on the wisconsin s0.1 interface:

 wisconsin(config)#  int s0.1  wisconsin(config-subif)#  no ip split-horizon eigrp 65001  

Example 11-37 lists the forwarding tables of the ohio and georgia routers after split horizon has been disabled on the wisconsin router.

Example 11-37 show ip route Command Output on the ohio and georgia Routers
 ohio#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        * - candidate default, U - per-user static route, o - ODR        P - periodic downloaded static route Gateway of last resort is not set      172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks D       172.16.5.0/25 [90/40537600] via 192.168.1.1, 00:00:04, Serial0 D       172.16.6.0/24 [90/41049600] via 192.168.1.1, 00:00:04, Serial0 D       172.16.2.0/24 [90/41049600] via 192.168.1.1, 00:00:04, Serial0 C       172.16.3.0/24 is directly connected, TokenRing0      192.168.1.0/29 is subnetted, 1 subnets C       192.168.1.0 is directly connected, Serial0 D    192.168.2.0/24 [90/41024000] via 192.168.1.1, 00:00:04, Serial0 ohio# _____________________________________________________________________ georgia#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        * - candidate default, U - per-user static route, o - ODR        P - periodic downloaded static route Gateway of last resort is not set      172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks D       172.16.5.0/25 [90/40537600] via 192.168.1.1, 00:01:41, Serial0 C       172.16.6.0/24 is directly connected, Ethernet0 D       172.16.2.0/24 [90/41049600] via 192.168.1.1, 00:01:41, Serial0 D       172.16.3.0/24 [90/41040128] via 192.168.1.1, 00:00:49, Serial0      192.168.1.0/29 is subnetted, 1 subnets C       192.168.1.0 is directly connected, Serial0 D    192.168.2.0/24 [90/41024000] via 192.168.1.1, 00:01:41, Serial0 georgia# 

At this point, you have full IP connectivity to all routers except the stillwater router, which resides in the RIP domain.

To fully integrate the RIP domain into EGIRP, you must ensure that the configuration has two elements:

  • Mutual redistribution between RIP and EIGRP on the minnesota router

  • All EIGRP routes summarized on a 24-bit boundary, the bit boundary the RIP network is on

To enable mutual redistribution on the minnesota router, use the redistribution and default-metric commands. Example 11-38 lists the configuration of the minnesota router.

Example 11-38 EIGRP and RIP Configuration of the minnesota Router
  !   router eigrp 65001   redistribute rip   network 172.16.0.0   network 192.168.2.0   default-metric 1544 100 254 1 1500   no auto-summary   !   router rip   redistribute eigrp 65001   network 172.16.0.0   default-metric 4   !  

The stillwater router now starts to receive routes from the minnesota router; however, it can receive only routes that have a 24-bit mask. The stillwater router will not have routes to the Frame Relay multipoint network, 192.168.1.0/29, or the Ethernet network, 172.16.5.0/25 on the wisconsin router. For the stillwater router to receive these routes, you must configure two summary addresses on a 24-bit boundary, on the point-to-point subnet between the wisconsin and minnesota router. Example 11-39 lists the configuration needed on the wisconsin router.

Example 11-39 EIGRP Summarization on the wisconsin Router
  !   interface Serial0.2 point-to-point   bandwidth 64   ip address 192.168.2.1 255.255.255.0   no ip directed-broadcast   ip summary-address eigrp 65001 192.168.1.0 255.255.255.0 5   ip summary-address eigrp 65001 172.16.5.0 255.255.255.0 5   frame-relay interface-dlci 111   !  

Example 11-40 lists the IP forwarding table of the stillwater router, followed by three ping s. To test complete IP connectivity, ping s have been issued from the stillwater router to the networks that were not originally on a 24-bit boundary.

Example 11-40 The show ip route Command Followed by a ping on the stillwater Router
 stillwater#  show ip route  Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP        D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default        U - per-user static route, o - ODR Gateway of last resort is not set R    192.168.1.0/24 [120/4] via 172.16.2.1, 00:00:01, Ethernet0 R    192.168.2.0/24 [120/4] via 172.16.2.1, 00:00:01, Ethernet0      172.16.0.0/24 is subnetted, 4 subnets R       172.16.5.0 [120/4] via 172.16.2.1, 00:00:01, Ethernet0 R       172.16.6.0 [120/4] via 172.16.2.1, 00:00:01, Ethernet0 C       172.16.2.0 is directly connected, Ethernet0 R       172.16.3.0 [120/4] via 172.16.2.1, 00:00:01, Ethernet0 stillwater#  ping 192.168.1.2  Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 68/70/72 ms stillwater#ping 192.168.1.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.3, timeout is 2 seconds: !!!!! Success rate is 100 percent (5/5), round-trip min/avg/max = 68/70/72 ms stillwater#ping 172.16.5.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 172.16.5.1, timeout is 2 seconds: !!!!! 

The final part of this lab is optional and involves configuring the georgia and ohio routers as EIGRP stub routers. Both routers still must advertise their connected networks; therefore, they need to use the connected keyword with the eigrp stub command. The only routers that need to be configured as stub routers are georgia and ohio; no configuration is necessary on the wisconsin router. The syntax needed on both routers resembles the following:

 georgia(config-router)#  eigrp stub connected  

To verify that a stub router is working, use the show ip eigrp neighbors detail command, as in Example 11-41. The last line of the output shows whether stub routing is enabled and what the stub router can advertise. ping s also should be issued from the RIP domain to the newly configured stub areas to verify IP routing.

Example 11-41 Verifying Stub Routing
 wisconsin#  show ip eigrp neighbors detail 65001  IP-EIGRP neighbors for process 65001 H   Address                 Interface   Hold Uptime   SRTT   RTO  Q  Seq Type                                         (sec)         (ms)       Cnt Num 2   192.168.1.3             Se0.1        178 00:00:53   52  1140  0  25    Version 12.0/1.1, Retrans: 1, Retries: 0    Stub Peer Advertising ( CONNECTED ) Routes 1   192.168.1.2             Se0.1        156 00:03:11  209  1254  0  28    Version 12.0/1.1, Retrans: 0, Retries: 0    Stub Peer Advertising ( CONNECTED ) Routes 0   192.168.2.2             Se0.2        130 01:01:01   26  2280  0  33    Version 11.3/1.0, Retrans: 1, Retries: 0 wisconsin# 

The last example (11-42) lists the complete configuration of the georgia, wisconsin, and minnesota routers.

Example 11-42 Configuration listings of georgia, wisconsin, and minnesota Routers
  hostname georgia   !  <<<text omitted>>>  !   interface Ethernet0   ip address 172.16.6.1 255.255.255.0   no ip directed-broadcast   !   interface Serial0   bandwidth 64   ip address 192.168.1.2 255.255.255.248   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   fair-queue 64 256 0   frame-relay map ip 192.168.1.1 102 broadcast   frame-relay map ip 192.168.1.3 102 broadcast   frame-relay lmi-type cisco   !   router eigrp 65001   network 172.16.0.0   network 192.168.1.0   no auto-summary   eigrp stub connected   !  _______________________________________________________________________  hostname wisconsin   !  <<<text omitted>>>  !   interface Ethernet0   ip address 172.16.5.1 255.255.255.128   no ip directed-broadcast   !   interface Serial0   no ip address   no ip directed-broadcast   encapsulation frame-relay   no ip mroute-cache   frame-relay lmi-type cisco   !   interface Serial0.1 multipoint   bandwidth 128   ip address 192.168.1.1 255.255.255.248   no ip directed-broadcast   no ip split-horizon eigrp 65001   frame-relay map ip 192.168.1.2 121 broadcast   frame-relay map ip 192.168.1.3 150 broadcast   !   interface Serial0.2 point-to-point   ip address 192.168.2.1 255.255.255.0   no ip directed-broadcast   ip summary-address eigrp 65001 192.168.1.0 255.255.255.0 5   ip summary-address eigrp 65001 172.16.5.0 255.255.255.0 5   frame-relay interface-dlci 111   !   interface Serial1   no ip address   no ip directed-broadcast   shutdown   !   interface BRI0   no ip address   no ip directed-broadcast   shutdown   isdn guard-timer 0 on-expiry accept   !   router eigrp 65001   network 172.16.0.0   network 192.168.1.0   network 192.168.2.0   no auto-summary  _______________________________________________________________________  hostname minnesota   !  <<<text omitted>>>  !   interface Ethernet2   ip address 172.16.2.1 255.255.255.0   media-type 10BaseT   !  <<<text omitted>>>  !   interface Serial0   ip address 192.168.2.2 255.255.255.0   encapsulation frame-relay   no ip mroute-cache   frame-relay interface-dlci 110   !   router eigrp 65001   redistribute rip   network 172.16.0.0   network 192.168.2.0   default-metric 1544 100 254 1 1500   no auto-summary   !   router rip   redistribute eigrp 65001   network 172.16.0.0   default-metric 4   !  
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CCIE Practical Studies, Volume I
CCIE Practical Studies, Volume I
ISBN: 1587200023
EAN: 2147483647
Year: 2001
Pages: 283
Authors: Karl Solie

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