■ Subnetting lets you efficiently allocate addresses by taking one large broadcast domain andīreaking it up into smaller, more manageable broadcast domains. Summary of Implementing Variable-Length Subnet Masks:
For a subnet of 30 hosts you will need a block size of 32. For example, if you have a subnet with 50 hosts then you can easily see from the table that you will need a block size of 64. RO2 = 192.168.1.118 Subnet mask 255.255.255.252Īs I mentioned earlier, having this table will prove very helpful. WAN Link from HQ to RO2 Network address = 192.168.1.116 /30 Mask for both links= 255.255.255.252 ( we got 252 by adding the bits value we borrowed i.e WAN links from HQ to RO1 Network address will be 192.168.1.112 /30 : WAN links = we are borrowing 6 bit with value of 4 If your network was originally using subnet 172.16.2.0 /24, you could reassign the following to your first two WAN interfaces using VLSM, as shown in Table 3.3 and Figure 3.3. RO1 address will start from 192.168.1.64 – Network address Therefore, the subnet mask used for only two hosts is 255.255.255.252, or /30. We are borrowing 3 bits with value of 32 this again is the closest we can get to the number of host needed. HQ address will look like this 192.168.1.0 /26 HQ Network Mask 255.255.255.192 – we got the 192 by adding the bit value from the left to the value we borrowed = 128+64=192 Total address space -192.168.1.2 to 192.168.1.62ġ92.168.1.63 will be the broadcast address (remember to reserve the first and last address for the Network and Broadcast) This is the closest we can get for 50 hosts.ġ92.168.1.62- Last usable address. We are borrowing 2 bits with value of 64. Lets begin with HQ with 50 hosts, using the table above: We will try and subnet 192.168.1.0 /24 to sooth this network which allows a total number of 254 hosts I recommend you get familiar with this table below.
The first thing to look out for is the number of subnets and number of hosts.
Looking at the diagram, we have three LANs connected to each other with two WAN links.
#WAN SUBNET 255 255 255 252 HOW TO#
The best way you can learn how to subnet a subnet (VLSM) is with examples. A classful addressing follows the general rule that has been proven to amount to IP address wastage.īefore you can understand VLSM, you have to be very familiar with IP address structure. It can also be called a classless IP addressing. To simplify further, VLSM is the breaking down of IP addresses into subnets (multiple levels) and allocating it according to the individual need on a network. Variable Length Subnet Mask (VLSM) in a way, means subnetting a subnet. Variable Length Subnet Masking – VLSM – is a technique that allows network administrators to divide an IP address space into subnets of different sizes, unlike simple same-size Subnetting. What is Variable Length Subnet Mask (VLSM)?
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