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CCNP ENARSI lab 2 of 35

EIGRP metrics, feasible successors and unequal-cost load balancing

Calculate EIGRP metrics by hand, find successors and feasible successors in the topology table, and use variance to load-share across a fibre and a slower microwave link, then prove why the same trick fails in the other direction.

Run this lab

It needs Lite: its 6 nodes are set to 6 vCPU and 4,096 MB in total. That fits the free demo too.

In your workspace: Shared, then CCNP ENARSI 300-410 guided labs, then 02 - EIGRP metrics feasible successors and unequal-cost load balancing

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Level
Intermediate
Time
About 60 minutes
Nodes need
6 vCPU, 4,096 MB
Smallest plan
Lite

The scenario

Brightwater Insurance connects its branch (R1) to head office (R4) over two paths: a fibre circuit through R2 and a microwave link through R3. EIGRP AS 100 already runs everywhere, but nobody has told it that the microwave link is only 100 Mbps, so today it treats both paths as equal. The network manager wants three things: the fibre preferred, the microwave kept ready as an instant backup, and some branch traffic to head office shared over the microwave so that paid-for capacity isn't idle.

You'll work out the metrics by hand first, then make EIGRP see the real link speeds, then tune load sharing, and finally prove how DUAL fails over.

DeviceInterfaceAddressConnects to
R1Gi0/010.0.12.1/24R2 Gi0/0 (fibre)
R1Gi0/110.0.13.1/24R3 Gi0/0 (microwave)
R1Gi0/2192.168.1.1/24PC1 192.168.1.10
R2Gi0/110.0.24.2/24R4 Gi0/0
R3Gi0/110.0.34.3/24R4 Gi0/1
R4Gi0/2192.168.4.1/24SRV 192.168.4.10
R*n*Lo010.255.0.n/32router ID n.n.n.n

Topology: R1 reaches R4 over R2 (top) or R3 (bottom). All links are GigabitEthernet in the lab; the microwave's real speed is 100 Mbps.

What you’ll practise

  • Calculate the classic EIGRP composite metric from bandwidth and delay
  • Identify successor, feasible distance, reported distance and feasible successor for a prefix
  • Apply the feasibility condition to explain why a path is or is not a feasible successor
  • Configure unequal-cost load balancing with variance and read traffic share counts
  • Watch DUAL fail over to a feasible successor without going active

The tasks

  1. Calculate the metric by hand
  2. Tell EIGRP the real speed of the microwave link
  3. Find the feasible successor
  4. Share traffic unequally with variance
  5. Watch DUAL fail over without going active

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of EIGRP metrics feasible successors and unequal-cost load balancing6 nodes, 6 links. Every link is listed as text below the diagram.R1R2R3R4PC1SRVGi0/2eth0Gi0/2eth0Gi0/0Gi0/0Gi0/1Gi0/0Gi0/1Gi0/0Gi0/1Gi0/1
6 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/0 to R2 Gi0/0
  • R1 Gi0/1 to R3 Gi0/0
  • R2 Gi0/1 to R4 Gi0/0
  • R3 Gi0/1 to R4 Gi0/1
  • R1 Gi0/2 to PC1 eth0
  • R4 Gi0/2 to SRV eth0
Nodes in EIGRP metrics, feasible successors and unequal-cost load balancing, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R2Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R3Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
R4Cisco IOSvvios-adventerprisek9-m.spa.159-3.m91 vCPU, 512 MB
PC1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
SRVVPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder CCNP ENARSI 300-410 guided labs.

  3. Open 02 - EIGRP metrics feasible successors and unequal-cost load balancing and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

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CloudLabBox is independent of Cisco. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.