This is one of multiple videos discussing IP submitting.
I've received a number of questions asking me to explain various submitting scenarios and this is one
of them.
So can the PC on the left configure it with this IP address 10 dot 1 or 2 4 8 to 1 slash 20 paying the
PC handled right with IP address tendered one at one time to do or to slash 20.
In this example I'm using Cisco Brodeur's as my PCs and I'm doing that because it's important that you
learn the Cisco Seelye.
However the subsetting behavior will be the same on Cisco versus a PC but it gives us a lot of options
to troubleshoot and test our subsetting scenarios.
So this is the IP address configured on gigabit 00 show run interface gigabit 00 shows us the IP address
configuration and show IP interface gigabit 00 shows us the IP address in a notation.
So that's the address inside a notation and that's the address configured in dotted decimal notation.
I'll do the same here show run interface gigabit 00 there's the IP address of PC to a router to acting
as PC to dotted decimal notation and show IP interface gigabit 00.
And what I'll do is only include the IP address of 10.
So there's the IP address in cit. notation.
I could do it this way which shows all the output but it's nice to have that output as well as the South
put on the same screen.
I'll do the same here show run interface gigabit 00 show IP interface gigabit 00 and I'll include 10.
So there's the IP address inside notation and dotted decimal notation.
So the question again can these two PCs ping each other.
So let's test it.
Paying 10 to 1 2 2 4 8 8 1.
Notice the pings are failing ping tendered wondered when I need to talk to pings or failing.
Why are they failing.
The answer is the PCs are in different subnets.
They connected physically to each other and we can see that by using the command show SCDP neighbors
notice Radio One is connected to Rodda to on gigabit 00 and brought a tube connected back on gigabit
00.
So they definitely connected to each other physically but they can't ping each other.
To help explain I've taken the IP addresses in decimal notation and converted them to binary.
So this is the binary representation of 10 of 1 to 2 4 8 to 1.
Here's the binary representation of 10 to 1 at 1 9 2 2. to slash 20 means 20 binary ones in the subnet
mask.
Here's the subnet mask with 20 binary ones.
I typically don't have a space between your binary bits but I've just added that to make it easier to
read.
So here's the first octet second octet third octet.
But notice four binary ones in the third octet and four binary zeros.
The same is shown here.
Slash twenty.
So are these two devices in the same subnet.
The answer is No.
Because notice the nitwit portion is different on these two devices.
I've highlighted the network portion in red the host portion as shown in balloon for devices to be in
the same subnet the network portion or subnet portion needs to be the same on both devices noticed via
the Submit portion is different.
So they are in different subnets and won't be able to ping each other unless you put a road between
them or change the subnet mask.
What would you change the subnet mask to to allow them to ping each other
and the entrées make the subnet portion this which means that the host portion is not changed.
To that.
So this is the host portion.
This is the network portion network portion is now the same.
That equates to 8 plus 8 16 17 18 binary bits which equates to 2 4 5 2 4 5 192.
So previously that was the IP address on the side and that was the IP address on the right hand side.
So we would change the IP address to 10 to 1 2 1 9 2 2 2 2 4 5 2 4 5 1 9 2 0 and on the side interface
gigabit to 0 0 IP address tend to add 1 to 2 4 8 2 1 2 4 5 2 4 5 1 9 2 0.
So same IP address will have changed is the subnet mask.
So can the rod on the right acting as our PC ping the Rhoda on the left acting as a PC.
And the answer is yes it can.
It dropped the first ping while doing an op but notice the device on the right ping the device on the
left and the device on the left can ping the device on the right.
And that's just because we changed the subnet mosque to slash 18 and put the devices in the same subnet.
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