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This chapter is from the book

Configuration Exercise: Configuring and Tuning EIGRP

In this exercise, you first configure EIGRP and investigate its default behavior. You next configure EIGRP summarization, a stub, and a default route.

Exercise Objectives

The objectives of this exercise are as follows:

  • Set up EIGRP
  • Investigate the default behavior of EIGRP
  • Optimize the EIGRP configuration

Visual Objective

Figure 3-37 illustrates the topology used and what you will accomplish in this exercise.

Figure 3-37

Figure 3-37 EIGRP Configuration Exercise Topology

Command List

In this exercise, you use the commands in Table 3-10, listed in logical order. Refer to this list if you need configuration command assistance during the exercise.

Table 3-10. EIGRP Configuration Exercise Commands

Command

Description

(config)#router eigrp 1

Enters configuration mode for EIGRP in autonomous system 1

(config-router)#network 10.x.0.0 0.0.255.255

Specifies that EIGRP should run within network 10.x.0.0/16

(config-router)#no auto-summary

Turns off automatic summarization at classful network boundaries

#show ip protocols

Displays the parameters and current state of all the active routing protocol processes

#debug ip eigrp

Displays EIGRP updates

(config-if)#ip summary-address eigrp 1 10.x.0.0 255.255.0.0

Creates and advertises a summary route 10.x.0.0/16 for EIGRP autonomous system 1 out of this interface

(config-router)#eigrp stub

Specifies that this router should behave as an EIGRP stub router

#show ip eigrp neighbors detail

Displays detailed EIGRP neighbor information

(config-if)#ip summary-address eigrp 1 0.0.0.0 0.0.0.0

Creates and advertises a default route for EIGRP autonomous system 1 out of this interface and suppresses all other specific routes

#show ip eigrp topology

Displays the EIGRP topology table

#show ip eigrp traffic

Displays EIGRP traffic statistics

#show ip eigrp interfaces

Displays information about interfaces configured for EIGRP

#show ip eigrp neighbors

Displays EIGRP neighbor information

Task 1: Configuring Basic EIGRP

In this task, you configure EIGRP on each router in your pod so that there are EIGRP routes from the core, between edge routers, and between the edge and the internal routers. Follow these steps:

  • Step 1 Shut down the serial interface between the internal routers (s0/0/0 on PxR3 and PxR4); this link is not used in this exercise.

    Solution:

    The following shows the required step on the P1R3 router:

    P1R3(config)#int s0/0/0
    P1R3(config-if)#shutdown
          
  • Step 2 Configure EIGRP on each router in your pod in autonomous system 1, using the appropriate network and wildcard values to include all interfaces in the EIGRP routing process. Disable autosummarization on the edge routers.

    Solution:

    The following shows the required steps on the P1R1 and P1R3 routers:

    P1R1(config)#router eigrp 1
    P1R1(config-router)#network 10.1.0.0 0.0.255.255
    P1R1(config-router)#network 172.31.1.0 0.0.0.255
    P1R1(config-router)#no auto-summary
    
    P1R3(config-if)#router eigrp 1
    P1R3(config-router)#network 10.1.0.0 0.0.255.255
  • Step 3 Verify that the routing protocols are set up correctly using the show ip protocols command. Make sure that the autonomous system number is correct and that all neighbors are exchanging routes.

    Solution:

    The following shows example output on the P1R1 router:

    P1R1#show ip protocols
    Routing Protocol is "eigrp 1"
      Outgoing update filter list for all interfaces is not set
      Incoming update filter list for all interfaces is not set
      Default networks flagged in outgoing updates
      Default networks accepted from incoming updates
      EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
      EIGRP maximum hopcount 100
      EIGRP maximum metric variance 1
      Redistributing: eigrp 1
      EIGRP NSF-aware route hold timer is 240s
      Automatic network summarization is not in effect
      Maximum path: 4
      Routing for Networks:
        10.1.0.0/16
        172.31.1.0/24
      Routing Information Sources:
        Gateway         Distance      Last Update
        10.1.1.3              90      00:00:37
        10.1.0.2              90      00:00:35
        172.31.1.3            90      00:00:35
      Distance: internal 90 external 170
    P1R1#
  • Step 4 Verify that routes from other routers in your pod and from the backbone router BBR1 are being recognized via EIGRP on each router.

    Solution:

    The following shows example output on the P1R1 router:

    P1R1#show ip route
    <output omitted>
    Gateway of last resort is not set
    
         172.31.0.0/24 is subnetted, 2 subnets
    D       172.31.2.0 [90/21024000] via 172.31.1.3, 00:04:41, Serial0/0/0
    C       172.31.1.0 is directly connected, Serial0/0/0
         10.0.0.0/24 is subnetted, 4 subnets
    D       10.1.2.0 [90/20514560] via 10.1.0.2, 00:10:08, Serial0/0/1
    C       10.1.1.0 is directly connected, FastEthernet0/0
    C       10.1.0.0 is directly connected, Serial0/0/1
    D       10.254.0.0 [90/20514560] via 172.31.1.3, 00:04:42, Serial0/0/0
    P1R1#

    The highlighted routes are being learned by EIGRP.

  • Step 5 Use debug ip eigrp on the internal routers in your pod to monitor the EIGRP queries.
  • Step 6 Shut down the serial interface between the edge routers (the S0/0/1 interface on PxR1 and PxR2).
  • Step 7 View the EIGRP queries sent to the internal routers.

    Solution:

    The following shows the required command on the P1R3 router, the configuration on the P1R1 router, and example output on the P1R3 router:

    P1R3#debug ip eigrp
    IP-EIGRP Route Events debugging is on
    P1R3#
    
    P1R1(config)#int s0/0/1
    P1R1(config-if)#shutdown
    
    P1R3#
    *Mar  6 02:19:11.363: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming QUERY
      packet
    *Mar  6 02:19:11.367: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.0.0/24 M
      4294967295 - 0 4294967295 SM 4294967295 - 0 4294967295
    *Mar  6 02:19:11.367: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.0.0/24 routing table
      not updated thru 10.1.1.1
    *Mar  6 02:19:11.367: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.2.0/24 M
      4294967295 - 20000000 4294967295 SM 4294967295 - 20000000 4294967295
    *Mar  6 02:19:11.367: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.2.0/24 routing table
      not updated thru 10.1.1.1
    *Mar  6 02:19:11.387: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.0.0/24- not in IP
      routing table
    *Mar  6 02:19:11.387: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.0.0/24 metric
      4294967295 - 20000000 4294967295
    *Mar  6 02:19:11.387: IP-EIGRP(Default-IP-Routing-Table:1): 10.1.2.0/24 - not in IP
      routing table
    *Mar  6 02:19:11.387: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.2.0/24 metric
      4294967295 - 20000000 4294967295
    P1R3#

    P1R3 receives a query for network 10.1.0.0/24 from P1R1; 10.1.0.0/24 is unreachable, as indicated by the infinite metric 4294967295. P1R3 replies to the query, indicating that 10.1.0.0/24 is unreachable (using the same infinite metric).

  • Step 8 Turn off all debugging.

    Solution:

    The following shows the required command on the P1R3 router:

    P1R3#no debug all
    All possible debugging has been turned off
    P1R3#
  • Step 9 Reenable the serial interface between the edge routers (the S0/0/1 interface on PxR1 and PxR2).

    Solution:

    The following shows the required configuration on the P1R1 router:

    P1R1(config)#int s0/0/1
    P1R1(config-if)#no shutdown
          

Task 2: Configuring EIGRP Summarization

In this task, you configure EIGRP route summarization. This will add stability and speed convergence of the network by controlling the scope of queries, minimizing update traffic, and minimizing routing table size. Follow these steps:

  • Step 1 Telnet to BBR1 (172.31.x.3) and verify that you see the specific subnet routes from your pod.

    Solution:

    The following shows sample output on the BBR1 router:

    BBR1>show ip route eigrp
          10.0.0.0/24 is subnetted, 7 subnets
    D       10.1.2.0 [90/20514560] via 172.31.1.2, 00:00:28, Serial0/0/0.1
    D       10.1.1.0 [90/20514560] via 172.31.1.1, 00:00:29, Serial0/0/0.1
    D       10.1.0.0 [90/21024000] via 172.31.1.2, 00:00:32, Serial0/0/0.1
                     [90/21024000] via 172.31.1.1, 00:00:32, Serial0/0/0.1
    BBR1>
  • Step 2 Manually configure the edge routers (PxR1 and PxR2) to summarize the pod EIGRP routes to BBR1 into a single 10.x.0.0/16 advertisement (where x is your pod number).

    Solution:

    The following shows the required configuration on the P1R1 router:

    P1R1(config)#int s0/0/0
    P1R1(config-if)#ip summary-address eigrp 1 10.1.0.0 255.255.0.0
    P1R1(config-if)#

    Both edge routers require the same summarization configuration.

  • Step 3 Telnet to BBR1 (172.31.x.3) and verify that you see only the summary route and not the more specific routes from your pod. If both edge routers are configured correctly, you should see two equal-cost paths available to BBR1.

    Solution:

    The following shows sample output on the BBR1 router:

    BBR1>show ip route eigrp
      10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks
    D    10.1.0.0/16 [90/20514560] via 172.31.1.2, 00:00:33, Serial0/0/0.1
                     [90/20514560] via 172.31.1.1, 00:00:33, Serial0/0/0.1
    BBR1>

    Only the summarized 10.1.0.0/16 route is displayed; there are two equal-cost routes to this network, via P1R1 and P1R2.

Task 3: Configuring the EIGRP Stub

Having optimized BBR1's routing table by summarizing the routes from the pod's edge routers to the core BBR1 router, you now limit the query traffic from the pod's edge routers to its internal routers. Follow these steps:

  • Step 1 Configure the internal routers (PxR3 and PxR4) as EIGRP stubs. Remember that this bounds queries but does not affect the routing table.

    Solution:

    The following shows the required configuration on the P1R3 router:

    P1R3(config)#router eigrp 1
    P1R3(config-router)#eigrp stub
          
  • Step 2 Verify that the edge router recognizes its internal EIGRP neighbor as a stub.

    Solution:

    The following shows sample output on the P1R1 router. The highlighted lines indicate that P1R1 sees P1R3 (10.1.1.3) as a stub:

    P1R1#show ip eigrp neighbors detail
    IP-EIGRP neighbors for process 1
    H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                                (sec)         (ms)       Cnt Num
    1   10.1.1.3                Fa0/0             10 00:02:05   12   200  0  12
        Version 12.4/1.2, Retrans: 0, Retries: 0
        Stub Peer Advertising ( CONNECTED SUMMARY ) Routes
        Suppressing queries
    0   10.1.0.2                Se0/0/1           12 00:06:46   25  1140  0  40
       Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 8
    2   172.31.1.3              Se0/0/0          159 00:18:03  225  1350  0  4340
       Restart time 00:04:37
       Version 12.4/1.2, Retrans: 0, Retries: 0, Prefixes: 6
    P1R1#
  • Step 3 The stub designation bounds query traffic and helps the router avoid getting into a stuck-in-active state, where EIGRP is unable to resolve routes for long periods. To demonstrate this situation, use the debug ip eigrp command on the internal router.
  • Step 4 Shut down the serial interface between the edge routers (the S0/0/1 interface between PxR1 and PxR2).
  • Step 5 Compared to the time before the internal routers were configured as stubs, notice that no queries are now being sent to the internal router. You should not see the "processing incoming QUERY" debug message on the internal routers, because they are configured as stub routers.

    Solution:

    The following shows the required command on the P1R3 router, the configuration on the P1R1 router, and example output on the P1R3 router. Queries are no longer being sent to the internal routers. P1R1 only sends the Update packet to P1R3:

    P1R3#debug ip eigrp
    IP-EIGRP Route Events debugging is on
    
    P1R1(config)#int s0/0/1
    P1R1(config-if)#shutdown
    P1R3#
    *Mar  6 02:32:34.507: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming UPDATE packet
    *Mar  6 02:32:34.507: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.0.0/24 M
      4294967295 - 0 4294967295 SM 4294967295 - 0 4294967295
    *Mar  6 02:32:34.507: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.2.0/24 M
      4294967295 - 20000000 4294967295 SM 4294967295 - 20000000 4294967295
    *Mar  6 02:32:34.523: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.0.0/24 metric
      4294967295 - 0 4294967295
    *Mar  6 02:32:34.523: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.2.0/24 metric
      4294967295 - 20000000 4294967295
    *Mar  6 02:32:34.543: IP-EIGRP(Default-IP-Routing-Table:1): Processing incoming REPLY packet
    *Mar  6 02:32:34.543: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.0.0/24 M
      4294967295 - 0 4294967295 SM 4294967295 - 0 4294967295
    *Mar  6 02:32:34.543: IP-EIGRP(Default-IP-Routing-Table:1): Int 10.1.2.0/24 M
      4294967295 - 20000000 4294967295 SM 4294967295 - 20000000 4294967295
    P1R3#
  • Step 6 Turn off debugging on the internal routers (PxR3 and PxR4).

    Solution:

    The following shows the required command on the P1R3 router:

    P1R3#no debug all
    All possible debugging has been turned off
    P1R3#
  • Step 7 Reenable the serial interface between the edge routers (the S0/0/1 interface between PxR1 and PxR2).

    Solution:

    The following shows the required configuration on the P1R1 router:

    P1R1(config)#int s0/0/1
    P1R1(config-if)#no shutdown
          

Task 4: Configuring an EIGRP Default Route

In this task, you advertise a default route from the edge routers to the internal routers via EIGRP. This change adds stability and speed convergence to the network by minimizing update traffic and routing table size. Follow these steps:

  • Step 1 Send a default route from the edge routers to the internal routers, and filter all specific routes. You can do this by configuring a summary route of 0.0.0.0 0.0.0.0 on each edge router, on the interface to the internal router.

    Solution:

    The following shows the required configuration on the P1R1 router:

    P1R1(config)#int fa0/0
    P1R1(config-if)#ip summary-address eigrp 1 0.0.0.0 0.0.0.0
          
  • Step 2 Examine the routing table on the internal routers. You should see the default routes and the connected routes, but the more specific routes from the edge router should have been filtered.

    Solution:

    The following shows sample output on the P1R3 router. Notice that the gateway of last resort is also now set on the internal routers:

    P1R3#show ip route
    <output omitted>
    Gateway of last resort is 10.1.1.1 to network 0.0.0.0
    
          10.0.0.0/24 is subnetted, 1 subnets
    C       10.1.1.0 is directly connected, FastEthernet0/0
    D*   0.0.0.0/0 [90/30720] via 10.1.1.1, 00:01:58, FastEthernet0/0
          
  • Step 3 Ping the TFTP server (10.254.0.254) from the internal router to verify connectivity.

    Solution:

    The following shows sample output on the P1R3 router. The ping is successful:

    P1R3#ping 10.254.0.254
    
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 10.254.0.254, timeout is 2 seconds:
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 28/30/32 ms
    P1R3#
  • Step 4 Examine the EIGRP topology table, EIGRP traffic statistics, information about interfaces configured for EIGRP, and EIGRP neighbors.

    Solution:

    The following shows sample output on the P1R1 router:

    P1R1#show ip eigrp topology
    IP-EIGRP Topology Table for AS(1)/ID(172.31.1.1)
    
    Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
           r - reply Status, s - sia Status
    
    P 0.0.0.0/0, 1 successors, FD is 28160
         via Summary (28160/0), Null0
    P 10.1.2.0/24, 1 successors, FD is 20514560
         via 10.1.0.2 (20514560/28160), Serial0/0/1
    P 10.1.1.0/24, 1 successors, FD is 28160
         via Connected, FastEthernet0/0
    P 10.1.0.0/16, 1 successors, FD is 28160
         via Summary (28160/0), Null0
    P 10.1.0.0/24, 1 successors, FD is 20512000
         via Connected, Serial0/0/1
    P 172.31.2.0/24, 1 successors, FD is 21024000
         via 172.31.1.3 (21024000/20512000), Serial0/0/0
    P 172.31.1.0/24, 1 successors, FD is 20512000
         via Connected, Serial0/0/0
    P 10.254.0.0/24, 1 successors, FD is 20514560
         via 172.31.1.3 (20514560/28160), Serial0/0/0
    
    P1R1#show ip eigrp traffic
    IP-EIGRP Traffic Statistics for AS 1
      Hellos sent/received: 907/905
      Updates sent/received: 341/35
      Queries sent/received: 6/7
      Replies sent/received: 7/6
      Acks sent/received: 33/40
      Input queue high water mark 2, 0 drops
      SIA-Queries sent/received: 0/0
      SIA-Replies sent/received: 0/0
      Hello Process ID: 150
      PDM Process ID: 88
    
    P1R1#show ip eigrp interfaces
    IP-EIGRP interfaces for process 1
    
                         Xmit Queue   Mean   Pacing Time   Multicast    Pending
    Interface        Peers  Un/Reliable  SRTT   Un/Reliable   Flow Timer   Routes
    Fa0/0              1        0/0         4       0/10          50           0
    Se0/0/1            1        0/0        35       5/190        346           0
    Se0/0/0            2        0/0        75       5/190        748           0
    P1R1#
    
    P1R1#show ip eigrp neighbors
    IP-EIGRP neighbors for process 1
    H   Address                 Interface       Hold Uptime   SRTT   RTO  Q  Seq
                                             (sec)         (ms)       Cnt Num
    0   10.1.0.2                Se0/0/1           14 00:07:39   35  1140  0  65
    1   10.1.1.3                Fa0/0             13 00:14:21    4   200  0  18
    2   172.31.1.3              Se0/0/0          139 00:30:19  151  1140  0  4341
    P1R1#
  • Step 5 Save your configurations to NVRAM.

    Solution:

    The following shows how to perform the required step on the P1R1 router:

    P1R1#copy run start
    Destination filename [startup-config]?
    Building configuration...[OK]

Exercise Verification

You have successfully completed this exercise when you achieve the following results:

  • You have successfully implemented EIGRP and have observed EIGRP query traffic.
  • You have summarized your pod addresses to the core.
  • You have optimized performance on the internal routers.
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