How to Test EIGRP Load-Balancing

eigrp
I have configured EIGRP on all routers.
From R1 I can see there are 2 unequal paths to get to 4.4.4.4 loopback on R4, that 's after I used Variance command.

R1#sh ip eigrp topology 
EIGRP-IPv4 Topology Table for AS(1)/ID(192.168.13.1)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
       r - reply Status, s - sia Status 

P 192.168.24.0/24, 1 successors, FD is 30720
        via 192.168.12.2 (30720/28160), FastEthernet0/0
P 192.168.34.0/24, 1 successors, FD is 33280
        via 192.168.12.2 (33280/30720), FastEthernet0/0
        via 192.168.13.3 (261120/28160), FastEthernet0/1
P 192.168.12.0/24, 1 successors, FD is 28160
        via Connected, FastEthernet0/0
P 4.4.4.4/32, 2 successors, FD is 158720
        via 192.168.12.2 (158720/156160), FastEthernet0/0
        via 192.168.13.3 (389120/156160), FastEthernet0/1
P 192.168.13.0/24, 1 successors, FD is 258560
        via Connected, FastEthernet0/1
        via 192.168.12.2 (35840/33280), FastEthernet0/0

R1#

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R1#sh ip route eigrp    
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, + - replicated route

Gateway of last resort is not set

      4.0.0.0/32 is subnetted, 1 subnets
D        4.4.4.4 [90/389120] via 192.168.13.3, 01:04:06, FastEthernet0/1
                 [90/158720] via 192.168.12.2, 01:04:06, FastEthernet0/0
D     192.168.24.0/24 [90/30720] via 192.168.12.2, 01:04:06, FastEthernet0/0
D     192.168.34.0/24 [90/33280] via 192.168.12.2, 01:04:06, FastEthernet0/0
R1#

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I tried Traceroute, but realized it will use just one path , even when I use that command over and over :Traceroute 4.4.4.4

R1#traceroute 4.4.4.4

Type escape sequence to abort.
Tracing the route to 4.4.4.4

  1 192.168.13.3 16 msec 52 msec 12 msec
  2 192.168.34.4 24 msec 28 msec 44 msec
R1#

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the only time it took the other path through R2, is when I cleared EIGRP neighborship
R1#clear ip eigrp neighbors

it worked just one time though...

I am not sure if   Load-Balancing is working , but I am not using proper command to test, or it is not working...

Any help ?

Thank you
jskfanAsked:
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Hemil AquinoNetwork EngineerCommented:
Always remember that those path called feasible successors are backup path in case of link failure.
Now, did you configure the bandwidth of each interface using different bandwidth? otherwise you will be using the same equal cost.
For example:

One link has bandwidth of 64k link
One link has bandwidth of 256k link

The way you can test it is trace route that ip 4.4.4.4. you successor is this ip 4.4.4.4 [90/389120] via 192.168.13.3, 01:04:06, FastEthernet0/1
if it respond with that ip. Good!. Now turn off that interface and try doing the same trace route. that way you will see it's working.

Remember Eigrp takes decision based on bandwidth and delay.

Let me know how it goes.
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JustInCaseCommented:
Since both EIGRP routes are placed in routing table with different cost traffic should be load balanced unequally. But generally, something is wrong with your output, path via 192.168.12.2 should be preferred - since it is path with the lower cost (currently path that is taken is via 192.168.13.3). I guessthat you run into GNS3 bug, try to save configurations and reload lab).
You can also increase number of probes during testing:
traceroute 4.4.4.4 probe 5
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jskfanAuthor Commented:
Sorry Predrag
I was increasing /decreasing the Bandwidth on R1 Fa0/1,   probably the output of topology and routing table was not at the same moment..

To answer Hemil Aquino, I believe what you area referring to is Fault- Tolerance, which means the feasible successor function will not kick in until the interface going through the Successor is down.

Load-Balancing should alternate between both paths... I could not find the good testing of it
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jskfanAuthor Commented:
I guess the load-balancing works now, but It is an equal Load-Balancing:

R1#traceroute 4.4.4.4

Type escape sequence to abort.
Tracing the route to 4.4.4.4

  1 192.168.12.2 24 msec
    192.168.13.3 16 msec
    192.168.12.2 16 msec
  2 192.168.34.4 24 msec
    192.168.24.4 24 msec
    192.168.34.4 20 msec
R1#
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jskfanAuthor Commented:
Unequal Load-balancing works now too, it is just I had to use  Traceroute  for 8 times , and it will choose one path then I  use it for about 20 times it will choose the other path...the ratio is about 20:8

Cannot find the command that will display the load-balancing ratio
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jskfanAuthor Commented:
probably this is the right command:

R1#sh ip route 4.4.4.4
Routing entry for 4.4.4.4/32
  Known via "eigrp 1", distance 90, metric 158720, type internal
  Redistributing via eigrp 1
  Last update from 192.168.12.2 on FastEthernet0/0, 00:11:29 ago
  Routing Descriptor Blocks:
  * 192.168.13.3, from 192.168.13.3, 00:11:29 ago, via FastEthernet0/1
      Route metric is 158720, traffic share count is 120
      Total delay is 5200 microseconds, minimum bandwidth is 100000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 2
    192.168.12.2, from 192.168.12.2, 00:11:29 ago, via FastEthernet0/0
      Route metric is 389120, traffic share count is 49
      Total delay is 5200 microseconds, minimum bandwidth is 10000 Kbit
      Reliability 255/255, minimum MTU 1500 bytes
      Loading 1/255, Hops 2
R1#


Share count through 192.168.13.3 is 120
Share count through 192.168.12.2 is 49
is about 2.45.......Well that  's the math I did to come up with the rounded Variance Value of 3.. but I am not sure why using traceroute to 4.4.4.4     about 8 times it will keep showing as going through 192.168.12.2  before it will show the path through :192.168.13.3 and then use Traceroute 4.4.4.4 about 20 times before I see it change back to the path through  192.168.12.2
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jskfanAuthor Commented:
though 20/8 = 2.5  which is close to almost 2.45 (I picked Variance 3)
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JustInCaseCommented:
Variance 3 is just a measure what is the worst route that can be place in routing table. It defines that if feasible successor route cost is less than 3 x successor cost it will be placed in routing table and will be used for unequal load balancing.

Generally, you can calculate ratio manually:
feasible successor metric/successor metric : feasible successor metric/feasible successor metric
389120/158720 : 389120/389120
2.4516 : 1
If that is multiplied with 49 that is showed by sh ip route 4.4.4.4
120.1284 : 49

If feasible successor route has different cost, although variance is still 3, it will have different load balance ratio.
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jskfanAuthor Commented:
Thank you Guys
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JustInCaseCommented:
You're welcome.
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