This is one of multiple IP addressing and submitting scenarios rather than just working out the subnets
for a scenario.
We can work them out and then configure the devices so that we can practically design and configure
a Cisco IP network.
OK so now that we've worked out the subnets we need to configure the devices in our network.
Let's assume that these switches are Layer 2 switches the local area networks need to support up to
60 hosts including an IP address allocated to the switches and the routers.
So let's start with a one on the first Ethan and interface.
I'm going to shut the interface.
We need to configure an IP address so 1 2 1 6 8 1 and this is why subsetting is so important.
What address are we going to allocate to the Rodda.
So the network we are using is 1 2 1 6 8 1.0 slice 26.
So let's see we want to use the last IP address for the router.
What is the first IP address and last IP address in the subnet.
So therefore addresses that we need to think about we need to think about the subnet address thats 1
on 2 1 6 8 1 0 is like 26.
Then we need to work out the first IP address.
Well first host that can be allocated then we need to work out the last IP address and we need to work
out what the broadcast address is.
So we already have the subnet address to work out the first IP address what you do is you set all binary
bits to 0 in the host portion except for the last bit.
So if you look at this that equates to 1 in decimal.
So the first host will be 1 9 2 1 6 8 1 1 slice 26
is our subnet.
Is our first host to work out to the last address in the subnet you fold the host portion only the host
portion with binary ones.
Except for the last but which is set to binary 0.
So notice the host portion is fulled with binary ones except for the last but.
So what does this equal.
Its 32 plus 16 which is 48 plus 8 which is 56 plus 4 which is 60 plus 2 which is 62.
So that equals 62 slash 26.
And what is the broadcast address equal to.
Now talk about easier ways to work this out but lets work it out as follows.
So to work out the broadcast what you do is you fool the host portion with binary ones and that will
give you 63 slash 26 so you can either count up all these bets or you do it in reverse.
You say it's 255 minus 128 minus 64.
This is why it's good to have this in the exam.
So when you go to the exam write this stone so that you can work out the values.
So this address is a cost address so we can't allocate that to the Rodda.
But what we can do is allocate the last IP address to the Rodda.
So the routing needs to be configured as 1 to 1 6 8 1 62 and the mosque is 2 4 5 2 4 5 2 for 5 1.
Remember the mosque is 2:55 255 255 192 IP address again is 1 9 2 1 6 8 1 62 which is what we've configured
on the router.
So I can press enter.
So we've now configured the router and as an example we should be able to paying ourselves which we
can and if we're paying 63 that is actually a broadcast
so show IP interface Fost.
Ethan It was 0 0 notice the Rotty is configured as follows IP addresses 1 9 2 1 6 8 162 slushed 26.
This is all hostes on my quick approved cost but this is a local subnet to provide cost.
So again show run interface if serious slash if there is zero there is our configuration.
Now we need to configure the hosts
and let's assume that we are going to configure the first host using the first IP address in the subnet.
So it's 1 9 2 1 6 8 1
so it needs to be configured as 1 9 2 1 6 8 1 1 slashed 26.
So 1.1 some of that mosque is 2 4 5 2 5 2 for 5 or 92 default gateway is 62 and all set the DNS to the
default gateway click safe lets start up that host and open up a console to the host.
So here it is.
I have config is zero IP address of the host is configured as follows.
Mosque is set to the following.
So Ping 1 on 2 1 6 8 1 2 1 and ping itself can we ping the router.
Yes we can.
Not to prove that we could do de-bug IP ICMP and ping from the host to the router.
You can see the pings are succeeding and we are getting it debug on the router.
Turn off the Debug.
Ping 1 on 2 1 6 8 1 2 1 Rodek and ping the first PC show on the interface brief again.
This is the IP address of the router.
Lets configure the second PC 61
so configure that statically
61 subnet mask 255 255 255 192 Rodda sixty two will set to the DNS to the Rodda
and stalked the PC up and open up a console.
So here's a boon to two PC to I-F config ethe zero IP address is 61 subnet mask is this Can we paying
the Rodda.
Yes we can.
Can we ping the other host.
Yes we can.
So we've configured the IP addresses on the subnet.
Now one last test.
Let's ping the broadcast address.
Notice the option we are told that we have to explicitly specify broadcast and when I broadcast the
router actually replies to that broadcast the other host doesn't.
But we are pinging the broadcast address when we use 63 so the broadcast isn't 1 9 2 1 6 8 1 255 the
broadcast address for the subnet is 1 9 2 1 6 8 1 63.
So we have successfully configured this subnet.
Now we need to configure the subnet and this gets a little bit more interesting because it's 1 9 2 1
6 8 1 64 slice 26.
Hope you found this video useful.
If it was of benefit to you please like it and please subscribe to my YouTube channel.
I wish you all the very best.