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This is one of multiple IP addressing and submitting scenarios rather than just working out the subnets

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for a scenario.

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We're going to work them out and then configure the devices so that we can practically design and configure

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a Cisco IP network in the previous video we can forget those genius three network.

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And we proved that devices can ping one another as an example.

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Xubuntu one PC one can ping both Ubuntu three and a boon to four.

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In other words this host can ping these hosts on the right hand side.

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Now one of the things that we did was we configure it to the serial link with Sublette 1 and 2 1 6 8

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1 128 slice 26.

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Now that subnet can support 62 hosts that's a waste of IP addresses when in actual fact a serial link

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only requires two IP addresses.

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So we allocated to this full subnet to the serial link the host portion currently contains six butts

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to the power of six minus two gives you the option to configure 62 host addresses but we only require

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two.

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So actually all we need are two bets in the host portion which will give us the option of having to

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host addresses in a subnet.

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Again they are two formulas for network she use the formula 2 to the power of x where x is the number

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of bits for host you use two to the power of x minus two.

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Two is the number of bytes in the host portion.

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We have to subtract two because we need a network address and a broadcast address in IP version 4.

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So two to the power of two minus two gives us for minus two which equals two.

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So taking this subnet which weve currently got configured on the Saral link lets submit it further.

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So as an example one brought a one currently show IP interface serial to slash zero.

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Shows us that 1 and 2 1 6 8 1 1:29 slice 26 is configured on the serial interface and that's because

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we configure the address on the serial interface.

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Now let's change that and optimize the subnet.

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So we only need two bits for the host portion so we can extend the subnet portion as follows.

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Now we are taking a already configured subnet and we submitting it again.

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So I'm going to denote this portion as the network portion because that's what we were given.

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This is the new subnet portion and this is the new host portion.

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So that's what we had originally.

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We've not changed it to slash 30.

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So this would be then new first subnet

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the second subnet would not be 128 we'd have to cycle through the binary options so we'd make this a

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one which in decimal is four.

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So 128 plus four.

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And let me update the subnet mask portion while we're here.

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So that's the new subnet mask.

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So this would be 128 plus 4 which is 132.

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So that would be the second Sublette.

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Now you might notice a trend here the difference between 128 and 132 is full.

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So the third subnet would be 132 plus 4 which would be 136 if you wanted to work out the binary you

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would cycle through the various options so current on this wire no current on this wire.

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That's an 8 in decimal 128 Plus 8 in decimal is 136.

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So if I were you to only work out say the first two or three subnets and then just see the pattern.

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These are incrementing in fours.

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So the next one would be 140.

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So just look at the pattern and it'll be a lot easier to work out to the next subnet.

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Now some other tricks that you can use if this is the next subnet.

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Then the first subnet broadcast address is one less than the next subnet.

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The next subnet is 132.

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So this subnets broad cross address is 131

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again to work out the broadcast address you fool the host portions with the ones so this is 128 plus

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two plus one or it's one less than the next subnet.

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So that's the new first subnet broadcast address.

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So the first host address is one more than the subnet address so it'll be a hundred and twenty nine

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in binary it looks like that the new first subnet last host is one less than the broadcast address so

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the broadcast address is 131.

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So this will be 130 in binary file.

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The host portion with Bhandari ones except for the last but here we've only got two bits.

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This is on and this is off.

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So that gives you the last host in the subnet.

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So that's an example of taking a subnet that we've created from a previous subnet and submitting it

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again to get new subnets in the network.

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So currently on our network we are using a 26 year what we'll do is change that to a slash 30 with the

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first host being 1 on 2 1 6 8 1 29 slash 30.

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And the second host being 1 9 2 1 6 8 1 130 slash 30.

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So that's the IP address on the first host of first Rodda.

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This is the IP address on the second Rodda we are going to stay with 1:29 and 130 but we are going to

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change the subnet mask its interface serial to slushes 0 IP address 1 9 2 1 6 8 1 1:29

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and the scenario needs to be mosque is a slush 30 because it's 8 plus 8 plus 8 plus six of slush 30

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mosque

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so this needs to change to 1 2 1 6 8 1 128 slash city that's the mosque you'll often find on several

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links because it supports two host addresses.

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So again this is a slash 30 mosque because we've got 30 binary ones in the subnet mosque.

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So this is 2:55 dot 2:55 dot 2:55 dot to 5 to.

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So this is going to be 2:05 to as the IP address.

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Notice the relationship goes down has come up again but we will probably have problems running it that

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way.

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So the site or say needs to be 2:05 to.

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In other words a slash 30 relationship has come up show IP interface serial to slash zero.

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Notice the mosque now used is a slash 30 and on side show IP interface serial to slushes zero.

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Notice the mosque used to use a slash 30 second right of one ping brought it to.

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Yes it can

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Ken PC one still paying PC three yes it can and can ping

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PC for yes it can.

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So let's trace to 1 on 2 1 6 8 1 65.

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You can see it goes to route 1 rather 2.

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And then the remote PC so we've successfully updated the subnets in this typology to only use two IP

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addresses on the serial link.

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The reason for doing that is we can increase the number of subnets that we have.

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So rather than only having a one subnet we've now increased the number of subnets to two to the power

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of four.

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So we've actually got 16 separate subnets that we can use each of which support to host addresses are

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being joined to this video.

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I wish you all the very best.