CCNP ROUTE Chapter 2 Lab 2-1, EIGRP Load Balancing (Version 7)

Topology

CCNP ROUTE Chapter 2 Lab 2-1, EIGRP Load Balancing (Version 7) 1

Objectives

  • Review a basic EIGRP configuration.
  • Explore the EIGRP topology table.
  • Identify successors, feasible successors, and feasible distances.
  • Use show and debug commands for the EIGRP topology table.
  • Configure and verify equal-cost load balancing with EIGRP.
  • Configure and verify unequal-cost load balancing with EIGRP.

Background

As a senior network engineer, you are considering deploying EIGRP in your corporation and want to evaluate its ability to converge quickly in a changing environment. You are also interested in equal-cost and unequal-cost load balancing because your network contains redundant links. These links are not often used by other link-state routing protocols because of high metrics. Because you are interested in testing the EIGRP claims that you have read about, you decide to implement and test on a set of three lab routers before deploying EIGRP throughout your corporate network.

Note: This lab uses Cisco 1941 routers with Cisco IOS Release 15.4 with IP Base. Depending on the Cisco IOS Software version, the commands available and output produced might vary from what is shown in this lab.

Required Resources

  • 3 routers (Cisco IOS Release 15.2 or comparable)
  • Serial and Ethernet cables

Step 0: Suggested starting configurations.

a. Apply the following configuration to each router along with the appropriate hostname. The exec-timeout 0 0 command should only be used in a lab environment.

Router(config)# no ip domain-lookup
Router(config)# line con 0
Router(config-line)# logging synchronous
Router(config-line)# exec-timeout 0 0

Step 1: Configure the addressing and serial links.

b. Create three loopback interfaces on each router and address them as 10.1.X.1/30, 10.1.X.5/30, and 10.1.X.9/30, where X is the number of the router. Use the following table or the initial configurations located at the end of the lab.

Router Interface IP Address/Mask
R1 Loopback11 10.1.1.1/30
R1 Loopback15 10.1.1.5/30
R1 Loopback19 10.1.1.9/30
R2 Loopback21 10.1.2.1/30
R2 Loopback25 10.1.2.5/30
R2 Loopback29 10.1.2.9/30
R3 Loopback31 10.1.3.1/30
R3 Loopback35 10.1.3.5/30
R3 Loopback39 10.1.3.9/30
R1(config)# interface Loopback 11
R1(config-if)# ip address 10.1.1.1 255.255.255.252
R1(config-if)# exit
R1(config)# interface Loopback 15
R1(config-if)# ip address 10.1.1.5 255.255.255.252
R1(config-if)# exit
R1(config)# interface Loopback 19
R1(config-if)# ip address 10.1.1.9 255.255.255.252
R1(config-if)# exit

R2(config)# interface Loopback 21
R2(config-if)# ip address 10.1.2.1 255.255.255.252
R2(config-if)# exit
R2(config)# interface Loopback 25
R2(config-if)# ip address 10.1.2.5 255.255.255.252
R2(config-if)# exit
R2(config)# interface Loopback 29
R2(config-if)# ip address 10.1.2.9 255.255.255.252
R2(config-if)# exit

R3(config)# interface Loopback 31
R3(config-if)# ip address 10.1.3.1 255.255.255.252
R3(config-if)# exit
R3(config)# interface Loopback 35
R3(config-if)# ip address 10.1.3.5 255.255.255.252
R3(config-if)# exit
R3(config)# interface Loopback 39
R3(config-if)# ip address 10.1.3.9 255.255.255.252
R3(config-if)# exit

c. Specify the addresses of the serial interfaces as shown in the topology diagram. Set the clock rate to 64 kb/s, and manually configure the interface bandwidth to 64 kb/s.

Note: If you have WIC-2A/S serial interfaces, the maximum clock rate is 128 kb/s. If you have WIC-2T serial interfaces, the maximum clock rate is much higher (2.048 Mb/s or higher depending on the hardware), which is more representative of a modern network WAN link. However, this lab uses 64 kb/s and 128 kb/s settings.

R1(config)# interface Serial 0/0/0
R1(config-if)# description R1-->R2
R1(config-if)# clock rate 64000
R1(config-if)# bandwidth 64
R1(config-if)# ip address 10.1.102.1 255.255.255.248
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface Serial 0/0/1 
R1(config-if)# description R1-->R3
R1(config-if)# bandwidth 64
R1(config-if)# ip address 10.1.103.1 255.255.255.248
R1(config-if)# no shutdown
R1(config-if)# exit

R2(config)# interface Serial 0/0/0
R2(config-if)# description R2-->R1
R2(config-if)# bandwidth 64
R2(config-if)# ip address 10.1.102.2 255.255.255.248
R2(config-if)# no shutdown
R2(config-if)# exit
R2(config)# interface Serial 0/0/1 
R2(config-if)# description R2-->R3
R2(config-if)# clock rate 64000
R2(config-if)# bandwidth 64
R2(config-if)# ip address 10.1.203.2 255.255.255.248
R2(config-if)# no shutdown
R2(config-if)# exit

R3(config)# interface Serial 0/0/0
R3(config-if)# description R3-->R1
R3(config-if)# clock rate 64000
R3(config-if)# bandwidth 64
R3(config-if)# ip address 10.1.103.3 255.255.255.248
R3(config-if)# no shutdown
R3(config-if)# exit
R3(config)# interface Serial 0/0/1 
R3(config-if)# description R3-->R2
R3(config-if)# bandwidth 64
R3(config-if)# ip address 10.1.203.3 255.255.255.248
R3(config-if)# no shutdown
R3(config-if)# exit

d. Verify connectivity by pinging across each of the local networks connected to each router.

e. Issue the show interfaces description command on each router. This command displays a brief listing of the interfaces, their status, and a description (if a description is configured). Router R1 is shown as an example.

R1# show interfaces description
Interface                      Status         Protocol Description
Em0/0                          admin down     down     
Gi0/0                          admin down     down     
Gi0/1                          admin down     down     
Se0/0/0                        up             up       R1-->R2
Se0/0/1                        up             up       R1-->R3
Lo11                           up             up       
Lo15                           up             up       
Lo19                           up             up       
R1#

f. Issue the show protocols command on each router. This command displays a brief listing of the interfaces, their status, and the IP address and subnet mask configured (in prefix format /xx) for each interface. Router R1 is shown as an example.

R1# show protocols
Global values:
  Internet Protocol routing is enabled
Embedded-Service-Engine0/0 is administratively down, line protocol is down
GigabitEthernet0/0 is administratively down, line protocol is down
GigabitEthernet0/1 is administratively down, line protocol is down
Serial0/0/0 is up, line protocol is up
  Internet address is 10.1.102.1/29
Serial0/0/1 is up, line protocol is up
  Internet address is 10.1.103.1/29
Loopback11 is up, line protocol is up
  Internet address is 10.1.1.1/30
Loopback15 is up, line protocol is up
  Internet address is 10.1.1.5/30
Loopback19 is up, line protocol is up
  Internet address is 10.1.1.9/30
R1#

Step 2: Configure EIGRP.

a. Enable EIGRP AS 100 for all interfaces on R1 and R2 using the commands. Do not enable EIGRP yet on R3. For your reference, these are the commands which can be used:

R1(config)# router eigrp 100
R1(config-router)# network 10.0.0.0

R2(config)# router eigrp 100
R2(config-router)# network 10.0.0.0

b. Use the debug ip routing and the debug ip eigrp 100 commands to watch EIGRP install the routes in the routing table when your routers become adjacent. (Note: The type of output you receive may vary depending upon the IOS.) You get output similar to the following.

R3# debug ip routing
IP routing debugging is on
R3# debug ip eigrp 100
R3# conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R3(config)# router eigrp 100
*Jun 22 11:06:09.315: RT: add router 2048, all protocols have local database
R3(config-router)# network 10.0.0.0
*Jun 22 11:06:18.591: %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.103.1 (Serial0/0/0) is up: new adjacency
*Jun 22 11:06:18.591: %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.203.2 (Serial0/0/1) is up: new adjacency
*Jun 22 11:06:19.055: RT: updating eigrp 10.1.102.0/29 (0x0)  :
    via 10.1.103.1 Se0/0/0  0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.102.0/29 via 10.1.103.1, eigrp metric [90/41024000]
*Jun 22 11:06:19.055: RT: updating eigrp 10.1.1.0/30 (0x0)  :
    via 10.1.103.1 Se0/0/0
R3(config-router)#end  0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.1.0/30 via 10.1.103.1, eigrp metric [90/40640000]
*Jun 22 11:06:19.055: RT: updating eigrp 10.1.1.4/30 (0x0)  :
    via 10.1.103.1 Se0/0/0  0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.1.4/30 via 10.1.103.1, eigrp metric [90/40640000]
*Jun 22 11:06:19.055: RT: updating eigrp 10.1.1.8/30 (0x0)  :
    via 10.1.103.1 Se0/0/0  0 1048578

*Jun 22 11:06:19.055: RT: add 10.1.1.8/30 via 10.1.103.1, eigrp metric [90/40640000]
*Jun 22 11:06:19.059: RT: updating eigrp 10.1.2.0/30 (0x0)  :
    via 10.1.103.1 Se0/0/0  0 1048578

*Jun 22 11:06:19.059: RT: add 10.1.2.0/30 via 10.1.103.1, eigrp metric [90/41152000]
*Jun 22 11:06:19.059: RT: updating eigrp 10.1.2.4/30 (0x0)  :
    via 10.1.103.1 Se0/0/0  0 1048578

R3#
R3(config-router)# end
R3#
R3#undebug all
All possible debugging has been turned off
R3#

Essentially, the EIGRP DUAL state machine has just computed the topology table for these routes and installed them in the routing table.

c. Check to see that these routes exist in the routing table with the show ip route command.

R3# show ip route
Codes: L - local, C - connected, S - static, 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
       i - IS-IS, su - IS-IS summary, 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, H - NHRP, l - LISP
       a - application route
       + - replicated route, % - next hop override

Gateway of last resort is not set

      10.0.0.0/8 is variably subnetted, 17 subnets, 3 masks
D        10.1.1.0/30 [90/40640000] via 10.1.103.1, 00:10:54, Serial0/0/0
D        10.1.1.4/30 [90/40640000] via 10.1.103.1, 00:10:54, Serial0/0/0
D        10.1.1.8/30 [90/40640000] via 10.1.103.1, 00:10:54, Serial0/0/0
D        10.1.2.0/30 [90/40640000] via 10.1.203.2, 00:10:54, Serial0/0/1
D        10.1.2.4/30 [90/40640000] via 10.1.203.2, 00:10:54, Serial0/0/1
D        10.1.2.8/30 [90/40640000] via 10.1.203.2, 00:10:54, Serial0/0/1
C        10.1.3.0/30 is directly connected, Loopback31
L        10.1.3.1/32 is directly connected, Loopback31
C        10.1.3.4/30 is directly connected, Loopback35
L        10.1.3.5/32 is directly connected, Loopback35
C        10.1.3.8/30 is directly connected, Loopback39
L        10.1.3.9/32 is directly connected, Loopback39
D        10.1.102.0/29 [90/41024000] via 10.1.203.2, 00:10:54, Serial0/0/1
                       [90/41024000] via 10.1.103.1, 00:10:54, Serial0/0/0
C        10.1.103.0/29 is directly connected, Serial0/0/0
L        10.1.103.3/32 is directly connected, Serial0/0/0
C        10.1.203.0/29 is directly connected, Serial0/0/1
L        10.1.203.3/32 is directly connected, Serial0/0/1
R3#

d. After you have full adjacency between the routers, ping all the remote loopbacks to ensure full connectivity.
You should receive ICMP echo replies for each address pinged.

e. Verify the EIGRP neighbor relationships with the show ip eigrp neighbors command.

R1# show ip eigrp neighbors
EIGRP-IPv4 Neighbors for AS(100)
H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq
                                                   (sec)         (ms)       Cnt Num
1   10.1.103.3              Se0/0/1                  13 00:14:20   49  2340  0  6
0   10.1.102.2              Se0/0/0                  10 00:29:14   37  2340  0  36
R1#

R2# show ip eigrp neighbors
EIGRP-IPv4 Neighbors for AS(100)
H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq
                                                   (sec)         (ms)       Cnt Num
1   10.1.203.3              Se0/0/1                  13 00:14:28   71  2340  0  7
0   10.1.102.1              Se0/0/0                  13 00:29:21   35  2340  0  36
R2#

R3# show ip eigrp neighbors
EIGRP-IPv4 Neighbors for AS(100)
H   Address                 Interface              Hold Uptime   SRTT   RTO  Q  Seq
                                                   (sec)         (ms)       Cnt Num
1   10.1.203.2              Se0/0/1                  13 00:14:07 1305  5000  0  37
0   10.1.103.1              Se0/0/0                  14 00:14:07   42  2340  0  37
R3#

Step 3: Examine the EIGRP topology table.

a. EIGRP builds a topology table containing all successor routes. The course content covered the vocabulary for EIGRP routes in the topology table. What is the feasible distance of route 10.1.1.0/30 in the R3 topology table in the following output?
_______________________________________________________________

R3# show ip eigrp topology
EIGRP-IPv4 Topology Table for AS(100)/ID(10.1.3.9)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P 10.1.102.0/29, 2 successors, FD is 41024000
        via 10.1.103.1 (41024000/40512000), Serial0/0/0
        via 10.1.203.2 (41024000/40512000), Serial0/0/1
P 10.1.1.8/30, 1 successors, FD is 40640000
        via 10.1.103.1 (40640000/128256), Serial0/0/0
P 10.1.3.0/30, 1 successors, FD is 128256
        via Connected, Loopback31
P 10.1.3.4/30, 1 successors, FD is 128256
        via Connected, Loopback35
P 10.1.3.8/30, 1 successors, FD is 128256
        via Connected, Loopback39
P 10.1.2.8/30, 1 successors, FD is 40640000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.2.0/30, 1 successors, FD is 40640000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.103.0/29, 1 successors, FD is 40512000
        via Connected, Serial0/0/0
P 10.1.203.0/29, 1 successors, FD is 40512000
        via Connected, Serial0/0/1
P 10.1.1.4/30, 1 successors, FD is 40640000
        via 10.1.103.1 (40640000/128256), Serial0/0/0
P 10.1.2.4/30, 1 successors, FD is 40640000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.1.0/30, 1 successors, FD is 40640000
        via 10.1.103.1 (40640000/128256), Serial0/0/0

R3#

b. The most important thing is the two successor routes in the passive state on R3. R1 and R2 are both advertising their connected subnet of 10.1.102.0/30. Because both routes have the same feasible distance of 41024000, both are installed in the topology table. This distance of 41024000 reflects the composite metric of more granular properties about the path to the destination network. Can you view the metrics before the composite metric is computed?
__________________________________________________________________

c. Use the show ip eigrp topology 10.1.102.0/29 command to view the information that EIGRP has received about the route from R1 and R2.

R3# show ip eigrp topology 10.1.102.0/29
EIGRP-IPv4 Topology Entry for AS(100)/ID(10.1.3.9) for 10.1.102.0/29
  State is Passive, Query origin flag is 1, 2 Successor(s), FD is 41024000
  Descriptor Blocks:
  10.1.103.1 (Serial0/0/0), from 10.1.103.1, Send flag is 0x0
      Composite metric is (41024000/40512000), route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 40000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
        Originating router is 10.1.1.9
  10.1.203.2 (Serial0/0/1), from 10.1.203.2, Send flag is 0x0
      Composite metric is (41024000/40512000), route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 40000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
        Originating router is 10.1.2.9
R3#
R3# show ip eigrp topology 10.1.102.0/29
EIGRP-IPv4 Topology Entry for AS(100)/ID(10.1.3.9) for 10.1.102.0/29
  State is Passive, Query origin flag is 1, 2 Successor(s), FD is 41024000
  Descriptor Blocks:
  10.1.103.1 (Serial0/0/0), from 10.1.103.1, Send flag is 0x0
      Composite metric is (41024000/40512000), route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 40000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
        Originating router is 10.1.1.9
  10.1.203.2 (Serial0/0/1), from 10.1.203.2, Send flag is 0x0
      Composite metric is (41024000/40512000), route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 40000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
        Originating router is 10.1.2.9
R3#

The output of this command shows the following information regarding EIGRP:

  • The bandwidth metric represents the minimum bandwidth among all links comprising the path to the destination network.
  • The delay metric represents the total delay over the path.
  • The minimum MTU represents the smallest MTU along the path.
  • If you do not have full knowledge of your network, you can use the hop count information to check how many Layer 3 devices are between the router and the destination network.

Step 4: Observe equal-cost load balancing.

EIGRP produces equal-cost load balancing to the destination network 10.1.102.0/29 from R1. Two equal-cost paths are available to this destination per the topology table output above.

a. Use the traceroute 10.1.102.1 command to view the hops from R3 to this R1 IP address. Notice that both R1 and R2 are listed as hops because there are two equal-cost paths and packets can reach this network via either link.

R3# traceroute 10.1.102.1 
Type escape sequence to abort.
Tracing the route to 10.1.102.1
VRF info: (vrf in name/id, vrf out name/id)
  1 10.1.203.2 24 msec
    10.1.103.1 12 msec
    10.1.203.2 24 msec
  R3#

Cisco IOS enables Cisco Express Forwarding (CEF), which, by default, performs per-destination load balancing. CEF allows for very rapid switching without the need for route processing. However, if you were to ping the destination network, you would not see load balancing occurring on a packet level because CEF treats the entire series of pings as one flow.

CEF on R3 overrides the per-packet balancing behavior of process switching with per-destination load balancing.

b. To see the full effect of EIGRP equal-cost load balancing, temporarily disable CEF and route caching so that all IP packets are processed individually and not fast-switched by CEF.

R3(config)# no ip cef

R3(config)# interface S0/0/0 
R3(config-if)# no ip route-cache
R3(config-if)# interface S0/0/1 
R3(config-if)# no ip route-cache

Note: Typically, you would not disable CEF in a production network. It is done here only to illustrate load balancing. Another way to demonstrate per-packet load balancing, that does not disable CEF, is to use the per-packet load balancing command ip load-share per-packet on outgoing interfaces S0/0/0 and S0/0/1.

c. Verify load balancing with the debug ip packet command, and then ping 10.1.102.1. Like any debug command, debug ip packet should be used with caution on a production network. Without any ACL filtering, this command will overwhelm the router’s CPU processes in a production environment. Issue the undebug all command to stop debug processing. You see output similar to the following:

R3# debug ip packet
IP packet debugging is on

R3# ping 10.1.102.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.102.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/36/44 ms
R3#
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/36/44 ms
R3#
*Jun 22 11:39:37.043: IP: tableid=0, s=10.1.203.3 (local), d=10.1.102.1 (Serial0/0/1), routed via RIB
*Jun 22 11:39:37.043: IP: s=10.1.203.3 (local), d=10.1.102.1 (Serial0/0/1), len 100, sending
*Jun 22 11:39:37.043: IP: s=10.1.203.3 (local), d=10.1.102.1 (Serial0/0/1), len 100, sending full packet
*Jun 22 11:39:37.087: IP: s=10.1.102.1 (Serial0/0/0), d=10.1.203.3, len 100, input feature, MCI Check(104), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE
*Jun 22 11:39:37.087: IP: tableid=0, s=
R3#10.1.102.1 (Serial0/0/0), d=10.1.203.3 (Serial0/0/1), routed via RIB
*Jun 22 11:39:37.087: IP: s=10.1.102.1 (Serial0/0/0), d=10.1.203.3, len 100, rcvd 4
*Jun 22 11:39:37.087: IP: s=10.1.102.1 (Serial0/0/0), d=10.1.203.3, len 100, stop process pak for forus packet
*Jun 22 11:39:37.087: IP: tableid=0, s=10.1.103.3 (local), d=10.1.102.1 (Serial0/0/0), routed via RIB
*Jun 22 11:39:37.087: IP: s=10.1.103.3 (local), d=10.1.102.1 (Serial0/0/0), len 100, sending
*Jun 22 11:39:37.087: IP: s=10.1.103.3 (local),
R3# d=10.1.102.1 (Serial0/0/0), len 100, sending full packet
*Jun 22 11:39:37.115: IP: s=10.1.102.1 (Serial0/0/0), d=10.1.103.3, len 100, input feature, MCI Check(104), rtype 0, forus FALSE, sendself FALSE, mtu 0, fwdchk FALSE

<output omitted>
R3# undebug all

Notice that EIGRP load-balances between Serial0/0/0 (s=10.1.103.3) and Serial0/0/1 (s=10.1.203.3). This behavior is part of EIGRP. It can help utilize underused links in a network, especially during periods of congestion.

Step 5: Analyze alternate EIGRP paths not in the topology table.

a. Issue the show ip eigrp topology command on R3 to see successors and feasible successors for each route that R3 has learned through EIGRP..

R3# show ip eigrp topology
EIGRP-IPv4 Topology Table for AS(100)/ID(10.1.3.9)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P 10.1.102.0/29, 2 successors, FD is 41024000
        via 10.1.103.1 (41024000/40512000), Serial0/0/0
        via 10.1.203.2 (41024000/40512000), Serial0/0/1
P 10.1.1.8/30, 1 successors, FD is 40640000
        via 10.1.103.1 (40640000/128256), Serial0/0/0
P 10.1.3.0/30, 1 successors, FD is 128256
        via Connected, Loopback31
P 10.1.3.4/30, 1 successors, FD is 128256
        via Connected, Loopback35
P 10.1.3.8/30, 1 successors, FD is 128256
        via Connected, Loopback39
P 10.1.2.8/30, 1 successors, FD is 40640000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.2.0/30, 1 successors, FD is 40640000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.103.0/29, 1 successors, FD is 40512000
        via Connected, Serial0/0/0
P 10.1.203.0/29, 1 successors, FD is 40512000
        via Connected, Serial0/0/1
P 10.1.1.4/30, 1 successors, FD is 40640000
        via 10.1.103.1 (40640000/128256), Serial0/0/0
P 10.1.2.4/30, 1 successors, FD is 40640000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.1.0/30, 1 successors, FD is 40640000
        via 10.1.103.1 (40640000/128256), Serial0/0/0

R3#

Perhaps you expected to see two entries to the R1 and R2 loopback networks in the R3 topology table. Why is there only one entry shown in the topology table?
__________________________________________________________________

b. Issue the show ip eigrp topology all-links command to see all routes that R3 has learned through EIGRP. This command shows all entries that EIGRP holds on this router for networks in the topology, including the exit serial interface and IP address of the next hop to each destination network, and the serial number (serno) that uniquely identifies a destination network in EIGRP.

R3# show ip eigrp topology all-links
EIGRP-IPv4 Topology Table for AS(100)/ID(10.1.3.9)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P 10.1.102.0/29, 2 successors, FD is 41024000, serno 13
        via 10.1.103.1 (41024000/40512000), Serial0/0/0
        via 10.1.203.2 (41024000/40512000), Serial0/0/1
P 10.1.1.8/30, 1 successors, FD is 40640000, serno 9
        via 10.1.103.1 (40640000/128256), Serial0/0/0
        via 10.1.203.2 (41152000/40640000), Serial0/0/1
P 10.1.3.0/30, 1 successors, FD is 128256, serno 3
        via Connected, Loopback31
P 10.1.3.4/30, 1 successors, FD is 128256, serno 4
        via Connected, Loopback35
P 10.1.3.8/30, 1 successors, FD is 128256, serno 5
        via Connected, Loopback39
P 10.1.2.8/30, 1 successors, FD is 40640000, serno 16
        via 10.1.203.2 (40640000/128256), Serial0/0/1
        via 10.1.103.1 (41152000/40640000), Serial0/0/0
P 10.1.2.0/30, 1 successors, FD is 40640000, serno 14
        via 10.1.203.2 (40640000/128256), Serial0/0/1
        via 10.1.103.1 (41152000/40640000), Serial0/0/0
P 10.1.103.0/29, 1 successors, FD is 40512000, serno 1
        via Connected, Serial0/0/0
P 10.1.203.0/29, 1 successors, FD is 40512000, serno 2
        via Connected, Serial0/0/1
P 10.1.1.4/30, 1 successors, FD is 40640000, serno 8
        via 10.1.103.1 (40640000/128256), Serial0/0/0
        via 10.1.203.2 (41152000/40640000), Serial0/0/1
P 10.1.2.4/30, 1 successors, FD is 40640000, serno 15
        via 10.1.203.2 (40640000/128256), Serial0/0/1
        via 10.1.103.1 (41152000/40640000), Serial0/0/0
P 10.1.1.0/30, 1 successors, FD is 40640000, serno 7
        via 10.1.103.1 (40640000/128256), Serial0/0/0
        via 10.1.203.2 (41152000/40640000), Serial0/0/1

R3#

What is the reported distance to the R1’s loopback networks using R1 and R2 as next-hop routers?
________________________________________________________________

c. Use the show ip eigrp topology 10.1.2.0/30 command to see the granular view of the alternate paths to 10.1.2.0, including ones with a higher reported distance than the feasible distance.

R3# show ip eigrp topology 10.1.2.0/30
IP-EIGRP (AS 100): Topology entry for 10.1.2.0/30
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 40640000
  Routing Descriptor Blocks:
  10.1.203.2 (Serial0/0/1), from 10.1.203.2, Send flag is 0x0
      Composite metric is (40640000/128256), Route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 25000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
  10.1.103.1 (Serial0/0/0), from 10.1.103.1, Send flag is 0x0
      Composite metric is (41152000/40640000), Route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 45000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2

When using the show ip eigrp topology command, why is the route to 10.1.2.0/30 through R1 (via 10.1.103.1) not listed in the topology table?
__________________________________________________________________

What is its reported distance from R1?
__________________________________________________________________

What is its feasible distance?
__________________________________________________________________

If the R2 Serial0/0/1 interface were shut down, would EIGRP route through R1 to get to 10.1.2.0/30? Why isn’t the switch to a new path a quick as it could be?
__________________________________________________________________

Record your answer, and then experiment by shutting down the R1 S0/0/1 interface while an extended ping is running as described below.

d. Start a ping with a high repeat count on R3 to the R1 Serial0/0/0 interface 10.1.102.1.

R3# ping 10.1.102.1 repeat 10000

e. Enter interface configuration mode on R1 and shut down port Serial0/0/1, which is the direct link from R1 to R3.

R1(config)# interface serial 0/0/1
R1(config-if)# shutdown

f. When the adjacency between R1 and R3 goes down, some pings will be lost. After pings are again being successfully received, stop the ping using Ctrl+Shift+^.

R3#ping 10.1.102.1 repeat 10000
Type escape sequence to abort.
Sending 10000, 100-byte ICMP Echos to 10.1.102.1, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
<output omitted>
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!
*Jun 22 12:56:45.739: %LINK-3-UPDOWN: Interface Serial0/0/1, changed state to down!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!
*Jun 22 12:56:45.739: %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.203.2 (Serial0/0/1) is down: interface down
*Jun 22 12:56:46.739: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/1, changed state to down!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
<output omitted>
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
*Jun 22 12:57:08.723: %LINK-3-UPDOWN: Interface Serial0/0/1, changed state to up
*Jun 22 12:57:09.723: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/1, changed state to up!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!
*Jun 22 12:57:10.003: %DUAL-5-NBRCHANGE: EIGRP-IPv4 100: Neighbor 10.1.203.2 (Serial0/0/1) is up: new adjacency!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Success rate is 99 percent (2039/2041), round-trip min/avg/max = 24/31/104 ms
R3#

How many packets were dropped?
_________________________________________________________________

Note: When examining the EIGRP reconvergence speed after deactivating the serial link between R1 and R3, the focus should not be on the count of lost ping packets but rather on the duration of connectivity loss or how long it took to perform a successful cutover. The router waits for up to two seconds for each sent ICMP ECHO request to receive a reply and only then does it send another ECHO request. If the router did not wait for the reply, the count of lost packets would be much higher. Because two packets were lost, the cutover took approximately 4 seconds.

Another factor to consider is that an interface deliberately delays the information about loss of connectivity for 2 seconds to prevent transient link flaps (link going up and down) from introducing instability into the network. If the real speed of EIGRP is to be observed, this delay can be made as short as possible using the command carrier-delay msec 0 on all serial interfaces.

g. Issue the no shutdown command on the R1 Serial0/0/1 interface before continuing to the next step.

Step 6: Observe unequal-cost load balancing.

Topology showing modified bandwidths as configured in step 6-b.

CCNP ROUTE Chapter 2 Lab 2-1, EIGRP Load Balancing (Version 7) 2

a. Review the composite metrics advertised by EIGRP using the show ip eigrp topology 10.1.2.0/30 command.

R3# show ip eigrp topology 10.1.2.0/30
IP-EIGRP (AS 100): Topology entry for 10.1.2.0/30
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 40640000
  Routing Descriptor Blocks:
  10.1.203.2 (Serial0/0/1), from 10.1.203.2, Send flag is 0x0
      Composite metric is (40640000/128256), Route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 25000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1
  10.1.103.1 (Serial0/0/0), from 10.1.103.1, Send flag is 0x0
      Composite metric is (41152000/40640000), Route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 45000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2

The reported distance for a loopback network is higher than the feasible distance, so DUAL does not consider it a feasible successor route.

b. To demonstrate unequal-cost load balancing in your internetwork, upgrade the path to the destination network through R1 with a higher bandwidth. Change the clock rate and bandwidth on the R1, R2, and R3 serial interfaces to 128 kb/s.

R1(config)# interface serial 0/0/0
R1(config-if)# bandwidth 128
R1(config-if)# clock rate 128000
R1(config-if)# interface serial 0/0/1
R1(config-if)# bandwidth 128

R2(config)# interface serial 0/0/0
R2(config-if)# bandwidth 128

R3(config)# interface serial 0/0/0
R3(config-if)# clock rate 128000
R3(config-if)# bandwidth 128

c. Issue the show ip eigrp topology 10.1.2.0/30 command again on R3 to see what has changed.

R3# show ip eigrp topology 10.1.2.0/30
EIGRP-IPv4 Topology Entry for AS(100)/ID(10.1.3.9) for 10.1.2.0/30
  State is Passive, Query origin flag is 1, 1 Successor(s), FD is 21152000
  Descriptor Blocks:
  10.1.103.1 (Serial0/0/0), from 10.1.103.1, Send flag is 0x0
      Composite metric is (21152000/20640000), route is Internal
      Vector metric:
        Minimum bandwidth is 128 Kbit
        Total delay is 45000 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 2
        Originating router is 10.1.2.9
  10.1.203.2 (Serial0/0/1), from 10.1.203.2, Send flag is 0x0
      Composite metric is (40640000/128256), route is Internal
      Vector metric:
        Minimum bandwidth is 64 Kbit
        Total delay is 25000 microseconds
        Reliability is 255/255
        Load is 3/255
        Minimum MTU is 1500
        Hop count is 1
        Originating router is 10.1.2.9
R3#

After manipulating the bandwidth parameter, the preferred path for R3 to the loopback interfaces of R2 is now through R1. Even though the hop count is two and the delay through R1 is nearly twice that of the R2 path, the higher bandwidth and lower FD results in this being the preferred route.

Note: Hop count is only mentioned to help you visualize the two paths. Hop count is not part of the composite EIGRP metric.

d. Issue the show ip route command to verify that the preferred route to network 10.1.2.0 is through R1 via Serial0/0/0 to next hop 10.1.103.1. There is only one route to this network due to the difference in bandwidth.

R3# show ip route eigrp

      10.0.0.0/8 is variably subnetted, 17 subnets, 3 masks
D        10.1.1.0/30 [90/20640000] via 10.1.103.1, 00:05:09, Serial0/0/0
D        10.1.1.4/30 [90/20640000] via 10.1.103.1, 00:05:09, Serial0/0/0
D        10.1.1.8/30 [90/20640000] via 10.1.103.1, 00:05:09, Serial0/0/0
D        10.1.2.0/30 [90/21152000] via 10.1.103.1, 00:05:09, Serial0/0/0
D        10.1.2.4/30 [90/21152000] via 10.1.103.1, 00:05:09, Serial0/0/0
D        10.1.2.8/30 [90/21152000] via 10.1.103.1, 00:05:09, Serial0/0/0
D        10.1.102.0/29 [90/21024000] via 10.1.103.1, 00:05:09, Serial0/0/0
R3#

e. The variance command is used to enable unequal-cost load balancing. Setting the variance command allows you to install multiple loop-free paths with unequal costs into the routing table. EIGRP will always install the successor with the best path. Additional feasible successors are candidates as for unequal-cost paths to be included in the routing table. These candidates must meet two conditions:

  • The route must be loop-free, a current feasible successor in the topology table.
  • The metric of the route must be lower than the metric of the best route (successor), multiplied by the variance configured on the router.

In the previous output, R3 shows the best path for 10.1.2.0/30 through R1 via 10.1.103.1. Examining the topology table on R3, there is also a feasible successor to this network through R2 via 10.1.203.1.

R3# show ip eigrp topology
EIGRP-IPv4 Topology Table for AS(100)/ID(10.1.3.9)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P 10.1.102.0/29, 1 successors, FD is 21024000
        via 10.1.103.1 (21024000/20512000), Serial0/0/0
        via 10.1.203.2 (41024000/20512000), Serial0/0/1
P 10.1.1.8/30, 1 successors, FD is 20640000
        via 10.1.103.1 (20640000/128256), Serial0/0/0
P 10.1.3.0/30, 1 successors, FD is 128256
        via Connected, Loopback31
P 10.1.3.4/30, 1 successors, FD is 128256
        via Connected, Loopback35
P 10.1.3.8/30, 1 successors, FD is 128256
        via Connected, Loopback39
P 10.1.2.8/30, 1 successors, FD is 21152000
        via 10.1.103.1 (21152000/20640000), Serial0/0/0
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.2.0/30, 1 successors, FD is 21152000
        via 10.1.103.1 (21152000/20640000), Serial0/0/0
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.103.0/29, 1 successors, FD is 20512000
        via Connected, Serial0/0/0
P 10.1.203.0/29, 1 successors, FD is 40512000
        via Connected, Serial0/0/1
P 10.1.1.4/30, 1 successors, FD is 20640000
        via 10.1.103.1 (20640000/128256), Serial0/0/0
P 10.1.2.4/30, 1 successors, FD is 21152000
        via 10.1.103.1 (21152000/20640000), Serial0/0/0
        via 10.1.203.2 (40640000/128256), Serial0/0/1
P 10.1.1.0/30, 1 successors, FD is 20640000
        via 10.1.103.1 (20640000/128256), Serial0/0/0

R3#

f. Issue the debug ip eigrp 100 command on R3 to show route events changing in real time. Then, under the EIGRP router configuration on R3, issue the variance 2 command, which allows unequal-cost load balancing bounded by a maximum distance of (2) × (FD), where FD represents the feasible distance for each route in the routing table. Using 10.1.2.0/30 as an example, (2) x (21152000) = 42304000. The FD of the feasible successor is 40640000 which is less that the variance-modified FD of 42304000. Therefore, the feasible successor route become an additional successor and is added to the routing table.

R3# debug ip eigrp 100
EIGRP-IPv4 Route Event debugging is on for AS(100)
R3# conf t
Enter configuration commands, one per line. End with CNTL/Z.
R3(config)# router eigrp 100
R3(config-router)# variance 2
R3(config-router)#
*Jun 22 13:16:19.087: EIGRP-IPv4(100): table(default): route installed for 10.1.102.0/29 (90/21024000) origin(10.1.103.1)
*Jun 22 13:16:19.087: EIGRP-IPv4(100): table(default): route installed for 10.1.102.0/29 (90/41024000) origin(10.1.203.2)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.1.8/30 (90/20640000) origin(10.1.103.1)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): 10.1.1.8/30 routing table not updated thru 10.1.203.2
*Jun 22 13:16:19.091: EIGRP-IPv4
R3(config-router)#(100): table(default): route installed for 10.1.2.8/30 (90/21152000) origin(10.1.103.1)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.2.8/30 (90/40640000) origin(10.1.203.2)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.2.0/30 (90/21152000) origin(10.1.103.1)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.2.0/30 (90/40640000) origin(10.1.203.2)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): 10.1
R3(config-router)#.103.0/29 routing table not updated thru 10.1.203.2
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.1.4/30 (90/20640000) origin(10.1.103.1)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): 10.1.1.4/30 routing table not updated thru 10.1.203.2
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.2.4/30 (90/21152000) origin(10.1.103.1)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.2.4/30 (90/40640000) origi
R3(config-router)#n(10.1.203.2)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): route installed for 10.1.1.0/30 (90/20640000) origin(10.1.103.1)
*Jun 22 13:16:19.091: EIGRP-IPv4(100): table(default): 10.1.1.0/30 routing table not updated thru 10.1.203.2
*Jun 22 13:16:19.103: EIGRP-IPv4(100): table(default): 10.1.102.0/29 - do advertise out Serial0/0/0
<output omitted>

g. Issue the show ip route command again to verify that there are now two routes to network 10.1.2.0. Notice that the two routes have different (unequal) metrics (feasible distances).

R3# show ip route eigrp

      10.0.0.0/8 is variably subnetted, 17 subnets, 3 masks
D        10.1.1.0/30 [90/20640000] via 10.1.103.1, 00:05:56, Serial0/0/0
D        10.1.1.4/30 [90/20640000] via 10.1.103.1, 00:05:56, Serial0/0/0
D        10.1.1.8/30 [90/20640000] via 10.1.103.1, 00:05:56, Serial0/0/0
D        10.1.2.0/30 [90/40640000] via 10.1.203.2, 00:05:56, Serial0/0/1
                     [90/21152000] via 10.1.103.1, 00:05:56, Serial0/0/0
D        10.1.2.4/30 [90/40640000] via 10.1.203.2, 00:05:56, Serial0/0/1
                     [90/21152000] via 10.1.103.1, 00:05:56, Serial0/0/0
D        10.1.2.8/30 [90/40640000] via 10.1.203.2, 00:05:56, Serial0/0/1
                     [90/21152000] via 10.1.103.1, 00:05:56, Serial0/0/0
D        10.1.102.0/29 [90/41024000] via 10.1.203.2, 00:05:56, Serial0/0/1
                       [90/21024000] via 10.1.103.1, 00:05:56, Serial0/0/0
R3#

h. These unequal-cost routes also show up in the EIGRP topology table as an additional successor. Use the show ip eigrp topology command to verify this. Notice there are two successor routes with different (unequal) feasible distances.

R3# show ip eigrp topology
EIGRP-IPv4 Topology Table for AS(100)/ID(10.1.3.9)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P 10.1.102.0/29, 2 successors, FD is 21024000
        via 10.1.103.1 (21024000/20512000), Serial0/0/0
        via 10.1.203.2 (41024000/20512000), Serial0/0/1
P 10.1.1.8/30, 1 successors, FD is 20640000
        via 10.1.103.1 (20640000/128256), Serial0/0/0
P 10.1.3.0/30, 1 successors, FD is 128256
        via Connected, Loopback31
P 10.1.3.4/30, 1 successors, FD is 128256
        via Connected, Loopback35
P 10.1.3.8/30, 1 successors, FD is 128256
        via Connected, Loopback39
P 10.1.2.8/30, 2 successors, FD is 21152000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
        via 10.1.103.1 (21152000/20640000), Serial0/0/0
P 10.1.2.0/30, 2 successors, FD is 21152000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
        via 10.1.103.1 (21152000/20640000), Serial0/0/0
P 10.1.103.0/29, 1 successors, FD is 20512000
        via Connected, Serial0/0/0
P 10.1.203.0/29, 1 successors, FD is 40512000
        via Connected, Serial0/0/1
P 10.1.1.4/30, 1 successors, FD is 20640000
        via 10.1.103.1 (20640000/128256), Serial0/0/0
P 10.1.2.4/30, 2 successors, FD is 21152000
        via 10.1.203.2 (40640000/128256), Serial0/0/1
        via 10.1.103.1 (21152000/20640000), Serial0/0/0
P 10.1.1.0/30, 1 successors, FD is 20640000
        via 10.1.103.1 (20640000/128256), Serial0/0/0

R3#

i. Load balancing over serial links occurs in blocks of packets, the number of which are recorded in the routing table’s detailed routing information. Use the show ip route 10.1.2.0 command to get a detailed view of how traffic is shared between the two links. The traffic share counters represent the ratio of traffic over the shared paths. In this case the ratio is 48:25 or about 2-to-1. The path through R1, 10.1.103.1, will be sent twice as much traffic as the path through R2, 10.1.203.2. A traffic share count of 1 on all routes indicates equal cost load balancing. If the traffic share count is 0, the path is not in use.

R3# show ip route 10.1.2.0   
Routing entry for 10.1.2.0/30
  Known via "eigrp 100", distance 90, metric 21152000, type internal
  Redistributing via eigrp 100
  Last update from 10.1.203.2 on Serial0/0/1, 00:10:11 ago
  Routing Descriptor Blocks:
    10.1.203.2, from 10.1.203.2, 00:10:11 ago, via Serial0/0/1
      Route metric is 40640000, traffic share count is 25
      Total delay is 25000 microseconds, minimum bandwidth is 64 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 3/255, Hops 1
  * 10.1.103.1, from 10.1.103.1, 00:10:11 ago, via Serial0/0/0
      Route metric is 21152000, traffic share count is 48
      Total delay is 45000 microseconds, minimum bandwidth is 128 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 2
R3#

j. Check the actual load balancing using the debug ip packet command. Ping from R3 to 10.1.2.1 with a high enough repeat count to view the load balancing over both paths. In the case above, the traffic share is 25 packets routed to R2 to every 48 packets routed to R1.

To filter the debug output to make it more useful, use the following extended access list.

R3(config)# access-list 100 permit icmp any any echo
R3(config)# end

R3# debug ip packet 100
IP packet debugging is on for access list 100

R3# ping 10.1.2.1 repeat 50

Type escape sequence to abort.
Sending 50, 100-byte ICMP Echos to 10.1.2.1, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*Jun 22 13:48:23.598: IP: tableid=0, s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), routed via RIB
*Jun 22 13:48:23.598: IP: s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), len 100, sending
*Jun 22 13:48:23.598: IP: s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), len 100, sending full packet
*Jun 22 13:48:23.626: IP: tableid=0, s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), routed via RIB
*Jun 22 13:48:23.626: IP: s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), len 100, sending
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*Jun 22 13:48:23.626: IP: s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), len 100, sending full packet
*Jun 22 13:48:23.654: IP: tableid=0, s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), routed via RIB
*Jun 22 13:48:23.654: IP: s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), len 100, sending
*Jun 22 13:48:23.654: IP: s=10.1.103.3 (local), d=10.1.2.1 (Serial0/0/0), len 100, sending full packet
!
R3 just switched to load-share the outbound ICMP packets to Serial0/0/1.
!
*Jun 22 13:48:24.954: IP: s=10.1.203.3 (local), d=10.1.2.1 (Serial0/0/1), len 100, sending
*Jun 22 13:48:24.954: IP: s=10.1.203.3 (local), d=10.1.2.1 (Serial0/0/1), len 100, sending full packet
*Jun 22 13:48:24.982: IP: tableid=0, s=10.1.203.3 (local), d=10.1.2.1 (Serial0/0/1), routed via RIB
*Jun 22 13:48:24.982: IP: s=10.1.203.3 (local), d=10.1.2.1 (Serial0/0/1), len 100, sending
*Jun 22 13:48:24.982: IP: s=10.1.203.3 (local), d=10.1.2.1 (Serial0/0/1
R3#), len 100, sending full packet
R3#

Note: If a deliberate metric manipulation is necessary on a router to force it to prefer one interface over another for EIGRP-discovered routes, it is recommended to use the interface-level command “delay” for these purposes. While the “bandwidth” command can also be used to influence the metrics of EIGRP-discovered routes through a particular interface, it is discouraged because the “bandwidth” will also influence the amount of bandwidth reserved for EIGRP packets and other IOS subsystems as well. The “delay” parameter specifies the value of the interface delay that is used exclusively by EIGRP to perform metric calculations and does not influence any other area of IOS operation.

k. Issue the show ip protocols command will verify the variance parameter and the number of maximum paths used by EIGRP. By default, EIGRP will use a maximum of 4 paths for load balancing. This value can be changed using the maximum-path EIGRP configuration command.

R3# show ip protocols
*** IP Routing is NSF aware ***

Routing Protocol is "application"
  Sending updates every 0 seconds
  Invalid after 0 seconds, hold down 0, flushed after 0
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Maximum path: 32
  Routing for Networks:
  Routing Information Sources:
    Gateway         Distance      Last Update
  Distance: (default is 4)

Routing Protocol is "eigrp 100"
  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-IPv4 Protocol for AS(100)
    Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
    NSF-aware route hold timer is 240
    Router-ID: 10.1.3.9
    Topology : 0 (base) 
      Active Timer: 3 min
      Distance: internal 90 external 170
      Maximum path: 4
      Maximum hopcount 100
      Maximum metric variance 2

  Automatic Summarization: disabled
  Maximum path: 4
  Routing for Networks:
    10.0.0.0
  Routing Information Sources:
    Gateway         Distance      Last Update
    10.1.103.1            90      00:39:03
    10.1.203.2            90      00:39:03
  Distance: internal 90 external 170

R3#

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dj501isboss@gmail.com
17 days ago

any answers for all the lab questions?