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Discovering computer networks: hands on in the Open Networking Lab
Discovering computer networks: hands on in the Open Networking Lab

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16.4 Testing the configuration

In this part you will use show commands to interrogate the configuration of the routers. Also you will use ping and traceroute commands to test connectivity between devices.

Watch the video below, which is about 2 minutes long. It demonstrates using the commands above to test connectivity, and then saving the configuration.

Testing the configuration

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Activity 9 Test yourself

2 minutes

  • Match the description to the correct command:

  • Using the following two lists, match each numbered item with the correct letter.

    1. ping

    2. tracert

    • a.A command that can be used to test whether there is end-to-end connectivity

    • b.A command that tracks the path of the traffic between routers and which can show you where in the device sequence a fault is.

    The correct answers are:
    • 1 = a
    • 2 = b

Activity 10 Try it out

Open PT Anywhere [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] in a new tab or window so you can read these instructions. This is the fully configured network.

1. In the last video you saw traceroute being used with an IPv4 address, but not with an IPv6 address. From PC-B2, use traceroute to check the route to the DNS server, which has an IPv6 address of 2001:DB8:FADE:1000::10. Is the result what you would expect?

2. The DNS server also has an IPv4 address, which is 172.20.32.10. Try pinging this from PC-B2. Explain your result.

Answer

1. When I did this I got:

1 1 ms 0 ms 0 ms 2001:DB8:FADE:100::1

2 0 ms 0 ms 0 ms 2001:DB8:FFFF:FFFF::1

3 0 ms 1 ms 0 ms 2001:DB8:FADE:1000::10

The first line is the response from Branch-B router’s G0/1 interface. The second line is from Central router’s G0/1 interface. The third line is from the DNS server. This is what we would expect if the network is working properly.

2. The ping fails because the Branch-B router is configured for only IPv6 addresses (and also the Central router’s G0/1 interface is configured only for IPv6 addresses). Even if these were dual stack, and able to handle both IPv4 and IPv6, the ping would fail because PC-B2 has no IPv4 address, so there is no address to send the response to the ping to.