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

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Discovering computer networks: hands on in the Open Networking Lab

4.1 Revision of IP addresses

In the last session you looked at how switches deliver data across a local area network. In this session you will look at routing. Routers operate at the Internet layer of the TCP/IP model and use IP addresses to deliver data across networks. Whereas switches worked with data frames, at the Internet layer data units become packets.

Now watch the following video, which is about 2 minutes long.

Revision of IP addresses

Download this video clip.Video player: 21_revision_of_ip_addresses.mp4
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Transcript

In this session we’ll be looking at routing. But firstly, a quick reminder of some of the work you did with IP addresses in earlier sessions – as we will be working with IP addresses in this part. You examined the PT Anywhere gateway’s IP address, which you found to be 192.168.0.1. You also saw how all devices on this network started with 192.168.0 with the final part used to identify a specific device on that network. The network itself would be allocated the IP address 192.168.0.0, which means all the devices could have a final digit between 2 and 254.

This type of address is one commonly used for private networks, specifically small home networks. Most of the networks we are concerned with at the moment will use addresses similar to this. They will also usually use the subnet mask 255.255.255.0. Remember the subnet mask shows the portion of the IP address that identifies the network.

Later, when we look at larger networks you will be using other types of IP address and subnet mask, such as those used in the next activity. Sometimes the network part is smaller and the host part bigger, so subnet masks such as 255.255.0.0 are used.

In this part we will be looking at how data is sent across different networks – looking at the IP addresses of source and destination devices is useful to determine whether two devices are on the same local network or whether they are on different networks.

End transcript
 
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Activity 1 Think about

5 minutes

Identify the network and host portions of the following IP addresses. The first has been done for you.

IP addressSubnet maskNetwork addressHost ID
192.168.1.105255.255.255.0192.168.1.0105
192.168.10.6255.255.255.0  
172.16.32.25255.255.0.0  
10.80.1.10255.0.0.0  

Answer

IP addressSubnet maskNetwork addressHost ID
192.168.1.105255.255.255.0192.168.1.0105
192.168.10.6255.255.255.0192.168.10.06
172.16.32.25255.255.0.0172.16.0.032.25
10.80.1.10255.0.0.010.0.0.080.1.10

It can also be useful to determine whether two devices are on the same local network or on different networks. Two devices on the same local network will have the same network address.

Activity 2 Test yourself

5 minutes

In which of the following are the source and destination devices on the same local network, and which are on different networks? The first has been done for you.

Source: IP address and subnet maskDestination: IP address and subnet maskSame local network or different networks?

192.168.1.105

255.255.255.0

192.168.1.250

255.255.255.0

Same: both have network address 192.168.1.0

192.168.10.6

255.255.255.0

192.168.10.252

255.255.255.0

 

192.16.32.25

255.255.0.0

192.168.31.32

255.255.255.0

 

10.80.1.10

255.255.0.0

10.80.2.26

255.255.0.0

 

Answer

Source: IP address and subnet maskDestination: IP address and subnet maskSame local network or different networks?

192.168.1.10

255.255.255.0

192.168.1.250

255.255.255.0

Same: both have network address 192.168.1.0

192.168.10.6

255.255.255.0

192.168.10.252

255.255.255.0

Same: both have network address 192.168.10.0

192.16.32.25

255.255.0.0

192.168.31.32

255.255.255.0

Different: source has network address 192.16.0.0 but destination has 192.168.31.0

10.80.1.10

255.255.0.0

10.80.2.26

255.255.0.0

Same: both have network address 10.80.0.0
OPNL_1

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