EIGRP and Delay

By Chris January 25, 2016 09:05

#EIGRP uses bandwidth and delay as components in its metric calculation by default. This lab uses a design and topology with all gigabit interfaces. The bandwidth part of the calculation uses the slowest bandwidth in a route, so all routes tie for bandwidth. How can you configure to influence EIGRP routes in this case? For this lab, you will add EIGRP configuration, as well as setting the link delay to a worse (higher) value on the link between R2 and R3. As a result, the different delay settings will cause the routers to avoid using the R2-R3 link.



Configure EIGRP on all routers so that EIGRP tends to send packets through router R1. The figure shows the one non-default delay setting.

This lab begins with all the interfaces shown in Figure 1 working and with IPv4 addresses configured. You job: add EIGRP configuration, along with setting the interface delay as shown.

The specific rules for this lab are:

  • Use ASN 5
  • Set the delay on all interfaces to match the delays in the figure
  • Do not use wildcard masks in the EIGRP configuration on routers R1, R2, and R3
  • Assume all interfaces in the figure are up and working
  • Assume all IPv4 addresses implied in the figure are configured
  • Assume all neighbor IP addresses are pingable
  • Use all defaults unless otherwise required to accomplish the lab requirements

Figure 1: Router Triangle with IP Subnets (EIGRP I – 2.jpg)


Initial Configuration

While you might be able to configure EIGRP based on the information supplied so far, the initial configurations of the three router can also be helpful. Example 1, 2 and 3 show the beginning configuration state of R1, R2 and R3.


Example 1: R1 Config


Example 2: R2 Config


Example 3: R3 Config


Answer on Paper, or Maybe Test in Lab

Next, write your answer on paper. Or if you have some real gear or other tools, configure the lab using them. If you do try this lab beyond just writing the answers on paper or in a text editor, to test the lab, check to see if all the routers know routes to all six subnets. Also, R2 should use R1 as the next-hop router for all EIGRP-learned routes, and R3 should also use R1 as the next-hop router for all EIGRP-learned routes.


Do this Lab with Cisco’s VIRL

You can do these labs on paper and still get a lot out of the lab. As an extra help, we have added files for the Virtual Internet Routing Lab (VIRL) software as well. The .VIRL file found here is a file that when used with VIRL will load a lab topology similar to this lab’s topology, with the initial configuration shown in the lab as well. This section lists any differences between the lab exercise and the .VIRL file’s topology and configuration.

Download this lab’s VIRL file!


Network and Host Device Info:

The .VIRL topology matches this lab topology exactly. The host info does as well.


Handy Host Commands:

To see PC IP address: ifconfig eth1

Ping example: ping -c 4

Trace example: tracepath

To connect to another node within the topology: telnet




Answers: L2 EtherChannel 1
Answers: Basic EIGRP
By Chris January 25, 2016 09:05
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