 Hello, dear learner friends, welcome to this video session on concept of subnetting and super netting related to the network layer. Myself, Mr. Vipul Kondekar from Walchand Institute of Technology, Sholapur. So these are the learning outcomes of this video. So you will understand how we can separate out the network ID and host ID with the help of network mask and you will be able to understand, differentiate between subnetting and super netting. These are the contents of this video. So you all know that when you have IP address representation, especially for IPv4. So the IP address is divided into two parts. Some part of the IP address is representing the address of the network while remaining part is representing the address of the host within that particular network. Now given this kind of differentiator between the net ID and host ID for different classes class A, class B and class C, how we will be able to separate out the network ID from host ID given from the given IP address. Now one very simple concept is use, the concept is masking. Now what is mask? The given IP address, concept of masking is given IP address is ANDed with a mask. As IP address is of 32 bits, your mask will be also of 32 bits. And then the result will be the beginning address or it will be the result will be address of the network. Now we know that Boolean operation performed by using the logical AND gate. If address bit is 1 and mask bit is 1, if mask bit is 1 more specifically whatever may the address bit, if address bit is 1 result will be 1, if address bit is 0 result will be 0 means address bit will be available to the output as it is. If mask bit is 1 and if mask bit is 0 then whatever may be the address bit what will be the result will be 0. Now in reference with the earlier diagram, so these can be the standard or default mask for class A, class B and class C. Because in class A I know that the network ID is present in the first byte. So all the first byte bits are made 1 in the mask and all other bits are made 0. So this will result into a mask called as 255.0.0.0, so this is the default mask, these are the default mask for class full IP representation for class A, class B and class C. Now we want to understand the concept of subnetting and then we will extend the concept of mask to the subnets and then we will call it as subnet mask. Now you look at this example, here you are finding one network but this network has got two levels of hierarchy. So for rest of the internet is getting connected to this network via this router R1 and this network has got a network ID 141.14, so this is the network ID part and remaining two bytes will be representing the host ID. So host ID can take host ID from 141.14.0.1 up to it is possible 141.14.255.254 because 255.255 belong to spatial IP address, fine. So there are two levels, so network ID and host ID is there but then what is the concept of subnetting? To use the IP addresses efficiently in class full IP representation, they come up with the solution of going for the subnetting. So in subnetting what is done, the same network here is divided into four different subnets and when you do subnetting, your host ID part gets divided into again two parts. Some part of the host ID will be representing the ID of the subnet and remaining bits will be representing the host ID part. So if you look at this, so this is a three level hierarchy where network has got network has got a network ID, that network is divided into subnets, each subnet has got subnetwork ID and then within the network, within that particular subnetwork, there are different hosts and those hosts will have host ID part. So this is what is the concept of subnetting where you are dividing the network into group of hosts called as subnets now. So this subnetting when you are using, so you are using hierarchical addressing. So it's like analogous to we use for the telephone system where you will be having telephone system with the area code first then the exchange code maybe STD code and then actual number okay or after that then maybe some extension number also in some cases. So this is a hierarchy. So what will happen is if you put an area code like if you put an area code or like country code, so the network will understand it the destination belongs to a particular country. So within that particular country which city, within that city which connection. So it will be easy to forward or to route the packet over the network when you use hierarchical addressing and then this three level of hierarchy is used when you are doing subnetting. Without subnetting the IP address will have two level of hierarchy. Now so as we have discussed the subnet the IP layer will IP address will have three layers one will be the network part then subnetwork part and then within the subnetwork what is the host ID part. So as this subnetting will result into improving the efficiency by not consuming the entire address space. So the problem with the classful addressing is wastage of IP addresses. That can be improved if you go for having subnetting within the network as well this subnetting will reduce the complexity of the router also. Now let us try to understand how exactly we get the addresses and subnet address and host ID part separated. Now just think of this IP address 141.14.192.2. So without subnetting it has two parts network ID this part is representing network ID why you are concluding that this is network ID because as this first byte is 141 you come to know that this address belongs to class B type of IP address. So in class B first two bytes will be representing first two decimal numbers will be representing the network ID part so remaining two will be host ID part. But then what I can do is I can have here in class B how many hosts I can have I can have host 2 raise to 16 65,534 number of hosts are possible. Now what I do is those hosts ID part I divide into two parts. So I divide that address range into subnetworks and then I am getting one subnet ID like 141.14.192.2 and if it is with subnetting then this part may be representing the subnet ID. So this is the three level hierarchy in the subnetting. Now exactly how we get the network address when you are having the mask and subnet mask let us try to understand with the help of this example. So as we have seen just now seen the concept of masking what we do in the masking is the IP address is ended with the default mask and that will result into the network address. So let us say this is the IP address and without submitting how I can get the network address is as this is the class B type of class B type of IP address I will use this default mask and then I will be able to separate out the network ID part. But now if my address is 141.14.70.24 and this is the subnet mask I am using. So this is the subnet mask I am using. So with the subnet mask you will be able to separate out the IP address of the network ID part of the IP address and that will be you can represent this in the binary you can do that ending operation and that will result into 141.14.64.0. So this is how you will be able to identify the network ID part. So this is how subnet mask is used to separate out network ID and host ID. Now comparison if you compare this with the default mask this was the default mask and this is the subnet mask. So what is happening here if you are using this as the subnet mask 255.255.224.0 in that case what you are doing is you are having these three bits representing the subnet ID. Means you can have these three bits can take eight different values you can have eight different subnetwares instead of having only one network what you can do is you can divide this network into eight different subnetwares each subnetwork will have its own subnet ID and within the subnetwork you will have means 13 bits are remaining for the host ID means 2 raised to 13 different hosts you can have within each subnetwork. So this subnet mask is used to separate out the host ID and network ID part though the subnetting is used. Now just concentrate on this example suppose it in subnetting what you do is you divide a big network into smaller networks and each network will be assigned network ID and because of that what will happen is the effective network ID part will increase effective network ID part will increase where network ID part will be summation of network ID without subnetting plus the address of the subnet how many bits you are using for the subnet. So in case of subnetting what we do is we are we need the address of the subnet as well subnet mask and using that subnet mask you will find the address effective width of the subnet and that will be width of the subnet or length of the subnet without subnetting plus log to the base 2 of s where s is representing number of subnets. So this will get added means network ID part will increase because subnet part is getting subnet ID part is getting added to it but exactly oppose it in supernetting what happens is what we do is we try to have collection of different small small network to form a big network that is called as supernetting and if you are doing supernetting what will happen is the length of the supernet will be given by this formula. So this is the difference here the length of the subnet ID gets increase as compared to without subnetting and if you are forming supernet so n supernet will be given by n which is the length of the network ID part original network ID part and then log to the base 2 of c where c is number of class c blocks you are combining to form that supernet. So effectively the network ID part will reduce in case of supernetting. So subnetting is dividing and supernetting is collecting the smaller networks to form a larger network. So this is one example so suppose a company needs 400 horse so what they have done is they have got 2 IP addresses 2 class C IP addresses and then what is done is those 2 addresses are combined to form a supernet address. So what is done is instead of using this these 2 addresses what that company uses is they uses 207.21.54.0 slash 23 forming a supernet. So here you find that supernet address in supernet address the network ID part is reduced here originally it was 24 now it has become 23. So this is one example how you can have supernetting where there are different class C networks and those class C networks are combined to form a single supernet work and then this is the comparison of what happens for the mass. So if this is the subnet mass if this is the default mass if you are using subnetting the mass width goes on increasing because you are having that network ID part added subnetwork ID part getting added and in case of supernet the size of the mass reduces. So easily you can understand by looking at this diagram. So these are the references used for this presentation. Thank you.