IPv6 Static Routes 3

By certskills August 15, 2016 09:05

Although this lab’s title is “IPv6 Static Routes 3”, it might be better called “Convoluted Fun with overlapping IPv6 Static Routes using Administrative Distance”. The purpose of the lab is to exercise a couple of specific ideas: how a router uses the most specific (that is, longest prefix) route to forward a packet, and how routers choose the routes with the best administrative distance.


First, to be clear: the design and requirements for this lab are not something you would do in a real network. But it works for understanding the concepts and commands.

The lab begins with all the routers except router R1 with useful IPv6 routes to all subnets as learned with EIGRP for IPv6. Routers R2, R3, R4, and R5 all run EIGRP for IPv6 and learn routes. However, for this exercise R1 does not and will not use an IPv6 routing protocol.

Your job for this lab is to configure static IPv6 routes on R1, with some admittedly strange requirements, all for the sake of getting a better understanding of what happens with overlapping IPv6 routes and administrative distance. The specific rules for this lab are:

  • Configure three static routes on router R1 for R5’s LAN subnet, as follows:
    • A route through R2 using an administrative distance of 50
    • A route through R3 using an administrative distance of 40
    • A route through R4 using an administrative distance of 60
  • Configure two overlapping static routes that are host routes, as follows:
    • A static host route to PC2 through next-hop router R2 using an administrative distance of 100
    • A static host route to PC4 through R4 using an administrative distance of 110
  • Assumptions:
    • All router interfaces shown in the lab are up, working and have correct IPv6 addresses assigned per the subnetting shown in the figure
    • IPv6 routing is enabled on all routers
    • All PC’s have been configured with an IPv6 address, gateway, and are working
    • Dynamic routing is enabled and working correctly for all appropriate prefixes for R2, R3, R4 and R5.


Figure 1: Router Triangle Topology


Initial Configuration

Examples 1, 2, 3, 4 and 5 show the beginning configuration state of R1, R2, R3, R4 and R5.


Example 1: R1 Config


Example 2: R2 Config


Example 3: R3 Config


Example 4: R4 Config


Example 5: R5 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 with those tools.

To test your solution if you happen to try it with VIRL or real gear, you can check by going to each of the PCs and attempt to ping the other PCs using the ping6 command. A more interesting test is to connect to router R5’s console and use the traceroute command to trace the path to the four PCs, in succession (2000::101, 2000::102, 2000::103, and 2000::104). If you try that, focus on the first router in the list in each case; it should be the next hop router per the static route you just configured for the lab.


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!

All interfaces in topology match the lab figure.

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.

Device IPv6 Address User/password
PC1 2001::101/64 cisco/cisco
PC2 2001::102/64 cisco/cisco
PC3 2001::103/64 cisco/cisco
PC4 2001::104/64 cisco/cisco


Handy Host Commands:

To see PC IP address: ifconfig eth1

Ping example: ping6 -c 4 2000::1

Trace example: tracepath6 2000::1

To connect to another node within the topology: telnet 2000::1

Answers: Dynamic NAT 1
Answers: IPv6 Static Routes 3
By certskills August 15, 2016 09:05
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  1. ghena October 21, 09:53

    Is EIRGP included in ICND1?

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