12/24/2023 0 Comments Vlsm subnetting chart excel![]() Unfortunately, the network administrator has to perform several mathematical steps (or use charts. ![]() Fill in the table in the Excel spreadsheet on Sheet 3 with the subnet ID, start IP, last IP, broadcast, subnet mask, and number of hosts for each department.ĭepartment | Subnet ID | Start IP | Last IP | Broadcast | Subnet Mask | Hosts Determine the broadcast address for each department:ħ. Determine the ending IP address for each department:Ħ. Enter the network you wish to subnet: Network Address, Mask bits. Determine the starting IP address for each department:ĥ. Determine the subnet mask for each department:Ĥ. Determine the number of subnets needed for each department:ģ. Determine the total number of hosts needed for each department:Ģ. IPOctet4BIN = Application.WorksheetFunction.1. And that second chart that we created allows us to very quickly find the beginning and the end of that particular subnet. Some people call this the subnet address. The second step of the subnetting phase is to calculate the network address. IPFullBIN = IPOctet1BIN & IPOctet2BIN & IPOctet3BIN & IPOctet4BINīuildBIN = BuildBIN & Mid(IPFullBIN, iCounter, 1) That chart is also going to show us how many devices per subnet will be on this particular network. If Mid(MaskOctet4BIN, iCounter, 1) And Mid(IPOctet4BIN, iCounter, 1) Then If Mid(MaskOctet3BIN, iCounter, 1) And Mid(IPOctet3BIN, iCounter, 1) Then If Mid(MaskOctet2BIN, iCounter, 1) And Mid(IPOctet2BIN, iCounter, 1) Then If Mid(MaskOctet1BIN, iCounter, 1) And Mid(IPOctet1BIN, iCounter, 1) Then IPSubnetCalc = MaskOctet1 & "." & MaskOctet2 & "." & MaskOctet3 & "." & MaskOctet4 '# 1 - Return Subnet Mask in dotted decimal # '# IP Subnet Calculator by Marcus Mansfield # Obviously, the X, Y/Z can be cell references.Įnjoy Public Function IPSubnetCalc(intFn%, IPandMaskInput$) X = 1 to 5 - See below for what each option does. Input is =IPSubnetCalc(X, YY.YY.YY.YY/ZZ ) Its very basic, but it does exactly what is says on the tin and works for me. Link to IP Subnet Calculator: Concepts of IP addressing, subnetting, VLSM. I'm going to assume you know how to add a VBA Function ( Or Macro etc ), If not I'll hope someone will reply to this thread with a simple How To. Open Excel and type your host address into cells A1 through A4, typing each byte. IPSubnetCalc = "Bitmask Error : Range 8 - 32, Excl. IPSubnetCalc = "Value Error, Octet > 255" If IPOctet1 > 255 Or IPOctet2 > 255 Or IPOctet3 > 255 Or IPOctet4 > 255 Then This corresponds to eight subnets and a new CIDR value of /27 (the column is in bold). The minimum number of hosts which can satisfy LAN B with the 29 hosts on our subnetting chart is 32. IPOctet4 = Mid(IPandMaskInput, Dot3 + 1, Slash1 - Dot3 - 1)īitMask = Right(IPandMaskInput, Len(IPandMaskInput) - Slash1) Step 3: Implement VLSM subnetting for the second-largest network (LAN B) The second-largest network, LAN B, requires 29 hosts. ![]() IPOctet3 = Mid(IPandMaskInput, Dot2 + 1, Dot3 - Dot2 - 1) IPOctet2 = Mid(IPandMaskInput, Dot1 + 1, Dot2 - Dot1 - 1) IPOctet1 = Mid(IPandMaskInput, 1, Dot1 - 1) ![]() If Dot1 = 0 Or Dot2 = 0 Or Dot3 = 0 Or Slash1 = 0 Then It can be used to increase the availability of subnets because of their variable size. The subnet design uses multiple masks in the same network, which means that more than one mask is used for a single class A, B, C, or different subnets of the network. ' 6 - Return Total Number of Host in the Network.ĭim IPOctet1%, IPOctet2%, IPOctet3%, IPOctet4%ĭim MaskOctet1%, MaskOctet2%, MaskOctet3%, MaskOctet4%ĭim IPNetwork1BIN$, IPNetwork2BIN$, IPNetwork3BIN$, IPNetwork4BIN$ĭot2 = InStr(Dot1 + 1, IPandMaskInput, ".")ĭot3 = InStr(Dot2 + 1, IPandMaskInput, ".") VLSM is the abbreviation of the Variable Length Subnet Mask. ' 1 - Return Subnet Mask in dotted decimal ' Author: Rui Sousa Change: Add funtion 6 to return number os hosts ' IP Subnet Calculator by Marcus Mansfield Rui Public Function IPSubnetCalc(intFn%, IPandMaskInput$) I've added a new option to calculate the number of available hosts in a network. For Class C IP addresses, the first three octets (24 bits / 3 bytes) represent the network ID and the last octet (8 bits / 1 bytes) is the host ID. ![]()
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