Configuring EIGRP Fault Tolerance

By arfs -

Routers Used: 3640 w/ NM-4T and NM-1FE-TX modules

IOS: c3640-jk9s-mz.124-16a

Objective
  • In this lab EIGRP will be configured over a full mesh topology and then tested to observe DUAL replace a successor with a feasible successor after a link failure.
Scenario
  • The International Travel Agency wants to run EIGRP on its core, branch, and regional routers. EIGRP is to be configured and tested for its ability to install alternate routes in the event of link failure.
Step 1
  • Build and configure the network according to the diagram, configuring EIGRP as indicated for AS 100. If using the configuration files from the previous lab, be sure to change IP addresses according to the diagram. Also, remove all loopback interfaces.
  • Set the bandwidth for each serial interface to reflect the diagram. Use the show interface
    command to verify the configuration.
  • Use ping and show ip route to verify the configuration and test connectivity between all routers.
Step 2
  • Verify that EIGRP maintains all routes to destination networks in its topology table.
    From the Dion2 router, issue the show ip eigrp topology all-links command:
    Dion2#show ip eigrp topology all-links
    IP-EIGRP Topology Table for AS(100)/ID(192.168.64.5)

    Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
    r - reply Status, s - sia Status

    P 192.168.72.0/24, 1 successors, FD is 2172416, serno 7
    via 192.168.64.6 (2172416/28160), Serial0/0
    via 192.168.1.1 (2174976/2172416), FastEthernet1/0
    P 192.168.64.0/30, 1 successors, FD is 2681856, serno 6
    via 192.168.64.6 (2681856/2169856), Serial0/0
    P 192.168.64.0/24, 1 successors, FD is 2169856, serno 8
    via Summary (2169856/0), Null0
    via 192.168.1.1 (2172416/2169856), FastEthernet1/0
    P 192.168.64.4/30, 1 successors, FD is 2169856, serno 4
    via Connected, Serial0/0
    P 192.168.1.0/24, 1 successors, FD is 28160, serno 1
    via Connected, FastEthernet1/0
  • Note: The feasible distance (FD) for the route 192.168.72.0 is 2172416. The reported distance (RD) of the route to 192.168.72.0 by way of 192.168.1.1 is 2172416. The RD less than the FD. The of the route to 192.168.72.0 by way of 192.168.1.1 greater than the RD of the route to 192.168.72.0 by way of 192.168.64.6
  • The router topology table for Dion2 includes two paths to the 192.168.72.0 network. Use the show ip route to determine which path is installed in the Dion2 routing table.
    Dion2#show ip route
    (output omitted)
    Gateway of last resort is not set

    D 192.168.72.0/24 [90/2172416] via 192.168.64.6, 00:36:41, Serial0/0
    192.168.64.0/24 is variably subnetted, 3 subnets, 2 masks
    D 192.168.64.0/30 [90/2681856] via 192.168.64.6, 00:36:41, Serial0/0
    D 192.168.64.0/24 is a summary, 00:36:38, Null0
    C 192.168.64.4/30 is directly connected, Serial0/0
    C 192.168.1.0/24 is directly connected, FastEthernet1/0
  • Both paths to 192.168.72.0 are listed in the topology table with their computed distance and reported distance in parentheses. The computed distance is listed first.
Step 3
  • To display debugging information about EIGRP feasible successor metrics (FSM) and to observe how EIGRP deals with the loss of a successor to a route, use the debug eigrp fsm command.
  • On the Dion2 router, issue the command debug eigrp fsm.
  • Next, shutdown or unplug the router serial connection to Dion2. This will cause the Dion2 router to lose its preferred route to 192.168.72.0 by way of 192.168.64.6.
  • Examine the debug eigrp fsm output for information regarding the route to 192.168.72.0, as shown in the following example:
    Dion2#debug eigrp fsm
    EIGRP FSM Events/Actions debugging is on
    Dion2#
    *Mar 1 01:01:13.455: DUAL: dest(192.168.64.4/30) not active
    *Mar 1 01:01:13.455: DUAL: rcvquery: 192.168.64.4/30 via 192.168.1.1 metric 429
    4967295/4294967295, RD is 2169856
    *Mar 1 01:01:13.459: DUAL: send REPLY(r1/n1) about 192.168.64.4/30 to 192.168.1
    .1
    *Mar 1 01:01:13.859: DUAL: Removing dest 192.168.64.4/30, nexthop 192.168.1.1,
    infosource 192.168.1.1
    Dion2#
    *Mar 1 01:01:24.819: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 100: Neighbor 192.168.64.6
    (Serial0/0) is down: holding time expired
    *Mar 1 01:01:24.823: DUAL: linkdown: start - 192.168.64.6 via Serial0/0
    *Mar 1 01:01:24.827: DUAL: Destination 192.168.72.0/24
    *Mar 1 01:01:24.831: DUAL: Find FS for dest 192.168.72.0/24. FD is 2172416, RD
    is 2172416
    *Mar 1 01:01:24.831: DUAL: 192.168.64.6 metric 4294967295/4294967295
    *Mar 1 01:01:24.835: DUAL: 192.168.1.1 metric 2174976/2172416 not found Dmi
    n is 2174976
    *Mar 1 01:01:24.839: DUAL: Peer total 1 stub 0 template 1
    *Mar 1 01:01:24.843: DUAL: Dest 192.168.72.0/24 entering active state.
    *Mar 1 01:01:24.843: DUAL: Set reply-status table. Count is 1.
    *Mar 1 01:01:24.843: DUAL: Not doing split horizon
    *Mar 1 01:01:24.847: DUAL: Destination 192.168.64.0/30
    *Mar 1 01:01:24.851: DUAL: Find FS for dest 192.168.64.0/30. FD is 2681856, RD
    is 2681856
    *Mar 1 01:01:24.851: DUAL: 192.168.64.6 metric 4294967295/4294967295 not fo
    und Dmin is
    Dion2# 4294967295
    *Mar 1 01:01:24.855: DUAL: Peer total 1 stub 0 template 1
    *Mar 1 01:01:24.859: DUAL: Dest 192.168.64.0/30 entering active state.
    *Mar 1 01:01:24.859: DUAL: Set reply-status table. Count is 1.
    *Mar 1 01:01:24.863: DUAL: Not doing split horizon
    *Mar 1 01:01:24.863: DUAL: Destination 192.168.64.0/24
    *Mar 1 01:01:24.867: DUAL: Destination 192.168.64.4/30
    *Mar 1 01:01:24.871: DUAL: Destination 192.168.1.0/24
    *Mar 1 01:01:24.879: DUAL: linkdown: finish
    *Mar 1 01:01:25.159: DUAL: rcvreply: 192.168.72.0/24 via 192.168.1.1 metric 217
    4976/2172416
    *Mar 1 01:01:25.163: DUAL: reply count is 1
    *Mar 1 01:01:25.163: DUAL: Clearing handle 0, count now 0
    *Mar 1 01:01:25.167: DUAL: Freeing reply status table
    *Mar 1 01:01:25.167: DUAL: Find FS for dest 192.168.72.0/24. FD is 4294967295,
    RD is 4294967295 found
    *Mar 1 01:01:25.175: DUAL: Removing dest 192.168.72.0/24, nexthop 192.168.64.6,
    infosource 192.168.64.6
    *Mar 1 01:01:25.179: DUAL: RT installed 192.168.72.0
    Dion2#/24 via 192.168.1.1
    *Mar 1 01:01:25.179: DUAL: Send update about 192.168.72.0/24. Reason: metric c
    hg
    *Mar 1 01:01:25.183: DUAL: Send update about 192.168.72.0/24. Reason: new if
    *Mar 1 01:01:25.187: DUAL: dest(192.168.64.0/30) active
    *Mar 1 01:01:25.187: DUAL: rcvreply: 192.168.64.0/30 via 192.168.1.1 metric 429
    4967295/4294967295
    *Mar 1 01:01:25.191: DUAL: reply count is 1
    *Mar 1 01:01:25.191: DUAL: Clearing handle 0, count now 0
    *Mar 1 01:01:25.195: DUAL: Freeing reply status table
    *Mar 1 01:01:25.195: DUAL: Find FS for dest 192.168.64.0/30. FD is 4294967295,
    RD is 4294967295 found
    *Mar 1 01:01:25.203: DUAL: Removing dest 192.168.64.0/30, nexthop 192.168.64.6,
    infosource 192.168.64.6
    *Mar 1 01:01:25.207: DUAL: Removing dest 192.168.64.0/30, nexthop 192.168.1.1,
    infosource 192.168.1.1
    *Mar 1 01:01:25.211: DUAL: No routes. Flushing dest 192.168.64.0/30
    Dion2#
    *Mar 1 01:01:42.187: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0,
    changed state to down
    *Mar 1 01:01:42.207: DUAL: rcvupdate: 192.168.64.4/30 via Connected metric 4294
    967295/4294967295
    *Mar 1 01:01:42.211: DUAL: Find FS for dest 192.168.64.4/30. FD is 2169856, RD
    is 2169856
    *Mar 1 01:01:42.211: DUAL: 0.0.0.0 metric 4294967295/4294967295 not found D
    min is 4294967295
    *Mar 1 01:01:42.215: DUAL: Peer total 1 stub 0 template 1
    *Mar 1 01:01:42.219: DUAL: Dest 192.168.64.4/30 entering active state.
    *Mar 1 01:01:42.219: DUAL: Set reply-status table. Count is 1.
    *Mar 1 01:01:42.223: DUAL: Not doing split horizon
    *Mar 1 01:01:42.235: DUAL: rcvupdate: 192.168.64.0/24 via Summary metric 429496
    7295/4294967295
    Dion2#
    *Mar 1 01:01:42.239: DUAL: Find FS for dest 192.168.64.0/24. FD is 2169856, RD
    is 2169856
    *Mar 1 01:01:42.243: DUAL: 0.0.0.0 metric 4294967295/4294967295
    *Mar 1 01:01:42.243: DUAL: 192.168.1.1 metric 2172416/2169856 not found Dmi
    n is 2172416
    *Mar 1 01:01:42.247: DUAL: Peer total 1 stub 0 template 1
    *Mar 1 01:01:42.251: DUAL: Dest 192.168.64.0/24 entering active state.
    *Mar 1 01:01:42.251: DUAL: Set reply-status table. Count is 1.
    *Mar 1 01:01:42.255: DUAL: Not doing split horizon
    *Mar 1 01:01:42.727: DUAL: dest(192.168.64.4/30) active
    *Mar 1 01:01:42.727: DUAL: rcvreply: 192.168.64.4/30 via 192.168.1.1 metric 429
    4967295/4294967295
    *Mar 1 01:01:42.731: DUAL: reply count is 1
    *Mar 1 01:01:42.731: DUAL: Clearing handle 0, count now 0
    *Mar 1 01:01:42.735: DUAL: Freeing reply status table
    *Mar 1 01:01:42.739: DUAL: Find FS for dest 192.168.64.4/30. FD is 4294967295,
    RD is 4294967295 found
    *Mar 1 01:01:42.743: DUAL: Removing dest 192.168.64.4/30, nexthop 0.0.0
    Dion2#.0, infosource 0.0.0.0
    *Mar 1 01:01:42.747: DUAL: Removing dest 192.168.64.4/30, nexthop 192.168.1.1,
    infosource 192.168.1.1
    *Mar 1 01:01:42.747: DUAL: No routes. Flushing dest 192.168.64.4/30
    *Mar 1 01:01:42.751: DUAL: rcvreply: 192.168.64.0/24 via 192.168.1.1 metric 217
    2416/2169856
    *Mar 1 01:01:42.755: DUAL: reply count is 1
    *Mar 1 01:01:42.755: DUAL: Clearing handle 0, count now 0
    *Mar 1 01:01:42.759: DUAL: Freeing reply status table
    *Mar 1 01:01:42.759: DUAL: Find FS for dest 192.168.64.0/24. FD is 4294967295,
    RD is 4294967295 found
    *Mar 1 01:01:42.767: DUAL: Removing dest 192.168.64.0/24, nexthop 0.0.0.0, info
    source 0.0.0.0
    *Mar 1 01:01:42.771: DUAL: RT installed 192.168.64.0/24 via 192.168.1.1
    *Mar 1 01:01:42.771: DUAL: Send update about 192.168.64.0/24. Reason: metric c
    hg
    *Mar 1 01:01:42.775: DUAL: Send update about 192.168.64.0/24. Reason: new if
    *Mar 1 01:01:42.787: DUAL: Find FS for dest 192.168.64.0/24. FD is 2172416, RD
    is 2172416
    *Mar 1 01:01:
    Dion2#42.791: DUAL: 192.168.1.1 metric 2172416/2169856 found Dmin is 2172416
    *Mar 1 01:01:42.791: DUAL: RT installed 192.168.64.0/24 via 192.168.1.1
  • The output shows DUAL attempting to locate a feasible successor
    (FS) for 192.168.72.0. In this case, DUAL failed to find a feasible successor, and the router entered the active state. After querying its EIGRP neighbors, Dion2 locates and installs a route to 192.168.72.0/24 by way of 192.168.1.1.
Step 4
  • Verify that the new route has been installed by using the show ip route command.
    Dion2#show ip route
    (output omitted)

    Gateway of last resort is not set

    D 192.168.72.0/24 [90/2174976] via 192.168.1.1, 00:02:02, FastEthernet1/0
    D 192.168.64.0/24 [90/2172416] via 192.168.1.1, 00:01:44, FastEthernet1/0
    C 192.168.1.0/24 is directly connected, FastEthernet1/0
  • Bring the Dion2 router serial interface back up. 192.168.64.6 will be restored as the preferred route to the 192.168.72.0 network.
Download

Popular posts from this blog

Cisco binary image unpacker

By arfs -
Image
Cisco binary image unpacker is a software that allows you to unpack the IOS and ASA images. Follow this steps to use this software for GNS3. With this way the Router loading process can be faster. This is useful for those of you that do start and stop Router frequently. Donwload Cisco image unpacker 0.1  for Windows. Extract thi zip file to your specific folder.. Copy the IOS file to this folder, for example "c3640-jk9s-mz.124-16a.bin". On windows command prompt, type the following command: "unpack c3640-jk9s-mz.124-16a.bin" (without ""). The output file stored in temporary folder, in my case "C:\Documents and Settings\dion\Local Settings\Temp". Open the folder and you will find the unpacked file "C3640-JK.bin", file size is about twofold. Copy "C3640-JK.bin" to your IOS folder. Your can also rename the file to "c3640-jk9s-mz.124-16a(unpacked).bin" Open GNS3, On the Edit menu, choose IOS image and hyper...
Read more

Connecting to Cisco Router console port using Linux

By arfs -
Image
I tried to connect my Ubuntu laptop to Cisco Router console port. I did successfully. What you will need: A roll-over cable (Cisco Console Cable). These are usually RJ-45 on the router side and serial on the PC side. If your laptop doesn’t have a serial port (like mine) you can get a 9-pin D-sub serial to USB cable. I got the BAFO USB Serial to DB9. I bought it in Ambassador Mall Kuningan Jakarta last night. Get Connected: Connect all the cables: USB -> Serial -> Crossover –> Console Port Download and Install Putty . root@dion-laptop:~# apt-get install putty Make sure that the USB to serial cable is recognized. root@dion-laptop:~# dmesg | grep tty [ 0.004000] console [tty0] enabled [ 1.923508] tty ptyx4: hash matches [ 131.637904] usb 3-2: pl2303 converter now attached to ttyUSB0 [ 173.768300] type=1503 audit(1243914954.561:5): operation="inode_permission" requested_mask="w::" denied_mask="w::" fsuid=0 name="/dev/ttyUSB0" pid=...
Read more

Examining the DR/BDR Election Process

By -
Image
Routers Used : 3640 w/ NM-1FE-TX IOS : c3640-jk9s-mz.124-16a Objective : In this lab, observe the OSPF DR and BDR election processing using debug commands. Then assign each OSPF interface a priority value to force the election of a specific router as a DR. Scenario The backbone of International Travel Agency’s enterprise network consists of three routers connected using an Ethernet core. Asterix1 has more memory and processing power than the other core routers. Unfortunately, other core routers are continually elected as the DR under the default settings. In the interest of optimization, ensure that Asterix1 is elected the DR, because it is best suited to handle associated extra duties, including management of Link State Advertisements (LSA) for Area 0. Investigate and correct this situation. Step 1 Build and configure the network according to the diagram. Use the configuration files from the previous lab if available . Configure OSPF on all Ethernet interfaces. A switch or hub is req...
Read more