IP Addresses 2

By certskills March 24, 2016 09:05

More daily lab practice! This one combines a little bit of subnetting math with IP address configuration. If you know how to calculate the IP addresses in a subnet, and you know how to configure IP addresses, make this one a speed test. See how long it takes you from the point of reading the specifics til you can type the config!


Configure the IP addresses for the LAN interfaces for the routers shown in the figure, per the subnets listed in the figure. The specific rules for this lab are:

  • Assume all interfaces shown in the lab are up and working
  • On each router’s G0/1 interface, use a last octet of 1, 2, 3, or 4 for routers R1, R2, R3, and R4, respectively.
  • On each router’s G0/2 interface, configure each router with the highest allowable address in the subnet.


Figure 1: Four Routers and Five Switches

Initial Configuration

Examples 1, 2, 3, and 4 show the beginning configuration state of R1, R2, R3, and R4.

Example 1: R1 Config

Example 2: R2 Config

Example 3: R3 Config

Example 4: R4 Config

Note also that the switch in the center of the network has all default configuration other than a hostname.

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.

For this lab, to check your results, your main option is to look at the configuration with the show running-config command. However, the figure shows the subnet IDs of the connected subnets, so you could use the show ip route command and ensure that the routes for connected subnets match those in the figure. Also, the four routers should be able to ping each other’s IP addresses in that center subnet, assuming that you also make the switch in the middle of the network work. This lab does not ask you to provide that configuration, but if you put all four switch interfaces in the same VLAN, and make sure those four interfaces are up, then the switch should allow the traffic between routers. For instance, a switch with all default configuration would work fine.

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!

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

Network Device Info:

All switches in this lab are unmanaged switches and the first available links were used to complete the connections

Host device info:

This table lists host information pre-configured in VIRL, information that might not be required by the lab but may be useful to you.


IP Address

Mac Address














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: VLAN Basics 3
Answers: IP Addresses 2
By certskills March 24, 2016 09:05
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