Config Lab: IPv6 Static Routes 2

Wendell Odom
By Wendell Odom September 28, 2021 15:05

IPv6 routing has many similarities with IPv4 routing; however, the length of the IPv6 addresses can sometimes get in the way of learning the main concepts. This next lab removes those barriers with a straightforward IPv6 static route configuration lab. All the IPv6 addresses and subnets are purposefully short (when abbreviated). Enjoy!

All about Config Labs

The blog has a series of lab exercises called “Config Labs.” Each lab presents a topology with the relevant initial configuration for each device. The lab also lists new requirements, after which you should create the additional configuration to meet those requirements. You can do the lab on paper, in a text editor, or use software tools like Cisco Packet Tracer or Cisco Modeling Labs.

Once you have created your answer, you can click various tabs at the bottom of this post to see the lab answers, comments about the lab, and other helpful information.

The Lab Exercise

Requirements

This lab uses a network topology with four routers and five IPv6 subnets. Each router connects to two subnets. Your job: add static IPv6 routes so that all routers have routes to all five IPv6 subnets, and that all the PCs in the figure can ping each other. The specific rules for this lab are:

  • None of the routers use a dynamic routing protocol.
  • Use global unicast addresses as next-hop, rather than link local addresses.
  • Assumptions:
    • All router interfaces shown in the lab are up, working, and have correct IPv6 addresses assigned.
    • All PCs have been configured appropriately based on the IPv6 subnet to which they are connected, respectively.

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. All five switches are layer 2 switches with all default configuration, which places all interfaces on the same switch into VLAN1.

Example 1: R1 Config

 

Example 2: R2 Config

 

Example 3: R3 Config

 

Example 4: R4 Config

Answer Options - Click Tabs to Reveal

You can learn a lot and strengthen real learning of the topics by creating the configuration – even without a router or switch CLI. In fact, these labs were originally built to be used solely as a paper exercise!

To answer, just think about the lab. Refer to your primary learning material for CCNA, your notes, and create the configuration on paper or in a text editor. Then check your answer versus the answer post, which is linked at the bottom of the lab, just above the comments section.

You can also implement the lab using the Cisco Packet Tracer network simulator. With this option, you use Cisco’s free Packet Tracer simulator. You open a file that begins with the initial configuration already loaded. Then you implement your configuration and test to determine if it met the requirements of the lab.

(Use this link for more information about Cisco Packet Tracer.)

Use this workflow to do the labs in Cisco Packet Tracer:

  1. Download the .pkt file linked below.
  2. Open the .pkt file, creating a working lab with the same topology and interfaces as the lab exercise.
  3. Add your planned configuration to the lab.
  4. Test the configuration using some of the suggestions below.

Download this lab’s Packet Tracer File

You can also implement the lab using Cisco Modeling Labs – Personal (CML-P). CML-P (or simply CML) replaced Cisco Virtual Internet Routing Lab (VIRL) software in 2020, in effect serving as VIRL Version 2.

If you prefer to use CML, use a similar workflow as you would use if using Cisco Packet Tracer, as follows:

  1. Download the CML file (filetype .yaml) linked below.
  2. Import the lab’s CML file into CML and then start the lab.
  3. Compare the lab topology and interface IDs to this lab, as they may differ (more detail below).
  4. Add your planned configuration to the lab.
  5. Test the configuration using some of the suggestions below.

Download this lab’s CML file!

 

Network Device Info:

Interfaces used in CML match the interfaces used in the Lab topology.

Host device info:

The CML topology matches the lab topology.

Device IP Address Mac Address User/password
PC1 2001::100/64 02:00:11:11:11:11 cisco/cisco
PC2 2002::100/64 02:00:22:22:22:22 cisco/cisco
PC3 2003::100/64 02:00:33:33:33:33 cisco/cisco
PC4 2004::100/64 02:00:44:44:44:44 cisco/cisco

Lab Answers Below: Spoiler Alert

Lab Answers: Configuration (Click Tab to Reveal)

Answers

Figure 1: Four Routers and Five Switches

Example 1: R1 Config

 

Example 2: R2 Config

 

Example 3: R3 Config

 

Example 4: R4 Config

Commentary, Issues, and Verification Tips (Click Tabs to Reveal)

Commentary

When configuring static routes, it is important to ensure that you have all of the correct IP subnet information because just a small difference in subnet mask can make a big difference in routing behavior.

For this lab, you were tasked with configuring static routes between the routers so that each of their LANs would be able to route packets to each other. Because there are four different routes in this topology, this means that there will be three remote LAN subnets that need to have routes configured per router.

For R1 the three remote LAN subnets are: 2002::/64, 2003::/64 and 2004::/64. The first route would be for R2’s LAN subnet. R1 and R2 both connect to the subnet between the routers (the 2000::/64 subnet) and R2’s IPv6 address on this subnet is 2000::2, making this address the next-hop address in the static route. The complete command to configure this static route would be be ipv6 route 2002::/64 2000::2.

Note that the ipv6 route command could have used a link-local address as the next-hop address. However, the lab specifically asked you to use global unicast addresses instead of link local addresses as the next-hop address.

R1’s second static route, for the subnet off R3’s G0/2 interface, would use R3’s IPv6 address on this shared LAN of 2000::3. The complete command to configure this static route would be be ipv6 route 2003::/64 2000::3.

R1’s third and final route would a route to the subnet off R4’s G0/2 interface. R1’s next-hop address would be R4’s IPv6 address on the central LAN (2000::4). The complete command to configure this static route would be ipv6 route 2004::/64 2000::4.

The routes configured on R2, R3, and R4 follow similar logic. On all of the routers, the route for 2001::/64 (off R1) points to R1’s 2000::1 address as the next-hop address. On all routers, the route for 2002::/64 (off R2) points to R2’s 2000::2 address as the next-hop address. On all routers, the route for 2003::/64 (off R3) points to R3’s 2000::3 address as the next-hop address. And you guessed it, on all routers, the route for 2004::/64 (off R4) points to R4’s 2000::4 address as the next-hop address.

Known Issues in this Lab

This section of each Config Lab Answers post hopes to help with those issues by listing any known issues with Packet Tracer related to this lab. In this case, the issues are:

# Summary Detail
1 None No known issues related to this lab.

 

Why Would Cisco Packet Tracer Have Issues?

(Note: The below text is the same in every Config Lab.)

Cisco Packet Tracer (CPT) simulates Cisco routers and switches. However, CPT does not run the same software that runs in real Cisco routers and switches. Instead, developers wrote CPT to predict the output a real router or switch would display given the same topology and configuration – but without performing all the same tasks, an actual device has to do. On a positive note, CPT requires far less CPU and RAM than a lab full of devices so that you can run CPT on your computer as an app. In addition, simulators like CPT help you learn about the Cisco router/switch user interface – the Command Line Interface (CLI) – without having to own real devices.

CPT can have issues compared to real devices because CPT does not run the same software as Cisco devices. CPT does not support all commands or parameters of a command. CPT may supply output from a command that differs in some ways from what an actual device would give. Those differences can be a problem for anyone learning networking technology because you may not have experience with that technology on real gear – so you may not notice the differences. So this section lists differences and issues that we have seen when using CPT to do this lab.

Beyond comparing your answers to this lab’s Answers post, you can test in Cisco Packet Tracer (CPT) or Cisco Modeling Labs (CML). In fact, you can and should explore the lab once configured. For this lab, once you have completed the configuration, try these verification steps. 

  1. Connect to the command line of each of the PCs and attempt to ping the other PCs. If each of the static routes was configured correctly, everyone should have connectivity to each other.
  2. Use an extended ping command to ping from each router’s G0/2 interface to each router’s G0/2 interface IP address. For instance, from R1, the command ping 2004::1 source 2001::1 would test the forward route to R4’s G0/2 subnet and the reverse route back to R1’s G0/2 subnet.
  3. Try the traceroute6 command on each PC, referencing another PC’s address, to see the various next-hop IPv6 addresses.

More Labs with Related Content!

Config Lab: IPv6 Static Routes 1
Config Lab: IPv6 Static Routes 3
Wendell Odom
By Wendell Odom September 28, 2021 15:05
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