Network Calculator Overview

The Network Calculator is an application designed to help network analysts or administrators.  The Network Calculator is composed of three separate calculators, each with its own functionality:  the Hexpert Calculator, the IP Subnet Calculator, and the Latency Calculator.


Copying Data to the Clipboard

All edit box text and tabular output produced by the three calculators, such as the Subnet/Host table in the IP Subnet Calculator, can be copied to the clipboard for use other applications like a word processor or spreadsheet program.  In addition, the Network Setup panel and Latency Graphs can be copied to the clipboard in bitmap format.

First, select the information that you would like to copy and then do one of the following:

1.	Select Copy from the Edit program menu.

2.	Press the shortcut key combination Ctrl+C.

3.	Click on a nearby clipboard button.


Switching Between Calculators

You may switch between calculators in three ways:

1.	Select a calculator from the Calculator program menu.

2.	Click on the calculator up and down arrows found toward the top of the Network Calculator window beside the individual calculator logos.  This cycles through the calculators in order.

3.	Use the shortcut key combinations (Ctrl+H = Hexpert Calculator, Ctrl+I = IP Subnet Calculator, and Ctrl+L = Latency Calculator).


The Hexpert Calculator

The Hexpert Calculator is a decimal/hexadecimal/binary conversion utility for quickly changing between number bases.

Base Converter Tab

Just type in a number in the appropriate base edit box and your number is converted to the other bases as you type.  The Clear button sets all numbers to zero while the Invert button performs a logical not or negation operation on the numbers.

Base Lookup Tab

The Base Lookup table is provided as a quick reference for looking up decimal to hexadecimal to binary number conversion for numbers 0 - 65535 (64 K).

The First, Last and Selected buttons scroll the table to the respective position.  The First and Last button are self-describing, while the Selected button jumps to the row in the table that the user last highlighted, which may have been scrolled out of view.

The Separators check box toggles whether separators (commas and spaces) are used in displaying values in the lookup table.

Bit-Swapper Tab

The Bit-Swapper tab provides a means for easily converting a 32-bit value to other bit format representations.  You can convert a value (entered by the user in logical or canonical form) to a bit-swapped value and a bit-reversed value.

The bit-swapped value is found by reversing the order of the bits within each byte of the original value on a byte-by-byte basis.   This type of conversion is common when analyzing both Ethernet and token ring/FDDI MAC addresses.

The bit-reversed value is found by reversing the ordering of the bits over the entire length of the 32-bit value.  Here, the least significant bit (LSB) becomes the most significant bit (MSB) and vice versa.

OUI Finder Tab

The OUI (Organizationally Unique Identifier) Finder tab is a utility that allows you to find the vender of a particular MAC OUI, which is assigned by the IEEE. Just enter in the OUI and press the enter key or click on the Search button and it quickly finds two different vendors of the OUI.  The first is the vendor of the OUI exactly as the user entered it and the second is the vendor of the bit-swapped OUI, which is common when analyzing both Ethernet and token ring/FDDI MAC addresses.  Not all OUIs have been assigned to vendors or are publicly available so either the first or second vendor may not be found.


The IP Subnet Calculator

The IP Subnet Calculator is useful for computing subnetting information given an IP address class and the number of subnet bits to be used.  For example, you may plan your network subnetting strategy by using the IP Subnet Calculator to optimize the use of subnet and host bits.

RFC 1878 contains the most recent information regarding subnetting policies. Please refer to it if you have any questions about the IP Subnet Calculator’s subnetting calculations.

Address Info Tab

The Address Info tab provides basic information about the use of address fields given an IP address class.  Classes A, B, C, and D (multicast) addresses are supported.

Fields on this tab include a color-coded Class Bit Map that shows the role of individual bits in the address' class, the binary and hexadecimal equivalents of the address entered by the user, and the Ethernet multicast address obtained (for class D addresses only).

Subnet Info Tab

The Subnet Info tab contains all of the user configurable parameters required to set up a subnetting policy, plus some additional derived information.

The Allow 1 Subnet Bit check box gives you the capability to toggle between allowing a minimum of one or two subnet bits.  Historically, subnets composed of all ones or all zeros were reserved.  Therefore the minimum number of subnet bits allowed was two, which allotted for two usable subnets (01 and 10 in binary, subnets 1 and 2 in decimal) and two reserved subnet addresses (00 and 11 in binary, subnets 0 and 3 in decimal).  However, RFC 1878 abolished this practice because the reserved subnets were generally not being used for any special purpose and was considered wasteful.  Thus the minimum number of subnet bits is now one, allowing for two usable subnets (0 and 1 in binary, and decimal).  The IP Subnet Calculator supports both methods because a lot of legacy hardware may not support the new subnetting procedures.

The Use Inversed Mask check box allows you to toggle the way the Subnet Mask combo box displays masks.  Normally, subnet masks are shown in a form where the binary mask is directly converted to dotted decimal representation, such as 255.255.128.0.  Some hardware requires that masks be entered in the inverse form, where the binary mask is inverted and then converted to dotted decimal, such as 0.0.127.255.

You may choose your subnetting policy in a number of different ways.  The Subnet Bits, Mask Bits, Subnet Mask, Max Subnets, and Max Hosts Per Subnet combo boxes all do essentially the same thing: They determine the number of subnet bits to use when creating the subnet mask.

The Subnet Bit Map field illustrates which bits are used for the network, subnet, and host portion of the IP address.

The Subnet Host Address Range is the range of all possible addresses hosts may legitimately own on the same subnet as the address in the IP Address edit box.  The subnet ID and subnet broadcast addresses of the subnet to which the current IP address belongs are displayed as well.

Subnets/Hosts Tab

The Subnets/Hosts tab provides a table of the subnet number, the subnet ID address, host address range, and the subnet broadcast address for each possible subnet in the current IP address scheme.  This table changes whenever the IP Address edit box or the number of subnet bits changes.

The First, Last and Selected buttons scroll the table to the respective position.  The First and Last button are self-describing, while the Selected button jumps to the row in the table that the user last highlighted, which may have been scrolled out of view.

CIDR Tab

CIDR stands for Classless InterDomain Routing, which is also known by the term supernetting.

The Use Inversed Mask check box allows you to toggle the way the Supernet Mask combo box displays masks.  Normally, supernet masks are shown in a form where the binary mask is directly converted to dotted decimal representation, such as 255.128.0.0.  Some hardware requires that masks be entered in the inverse form, where the binary mask is inverted and then converted to dotted decimal, such as 0.127.255.255.

Similar to the Subnet Info tab, the CIDR tab contains multiple combo boxes for specifying how many bits to use in the supernet mask and the values all corrospond to each other.

The Route field provides the base address to use when masking CIDR domains. The Supernet Address Range displays the range of possible sub-domain addresses.


The Latency Calculator

The Latency Calculator is used for computing estimated packet latency between two nodes over a series of network segments.  You may insert, move, and customize networks as you see fit.  Latency for each network is computed by dividing packet size by bandwidth.  This data is summarized in a time distribution table and graph.

Network Setup Tab

The Network Setup tab is where you can arrange a series of networks in an easy to use drag and drop fashion.  Please see Setting Up a Series of Networks for instructions on adding and removing networks.

The Network Setup panel can be copied to the clipboard in bitmap format.

Latency Statistics Tab

The Packet Direction option allows you to select the mode of latency calculation displayed.  Clt -> Svr and Clt <- Svr display the one way latency encountered going from client to server (Node A to Node B) or vice versa, respectively.  The Clt <-> Svr option displays the round trip latency from client to server and back.

Latency Graphs Tab

The Latency Graphs tab visually displays the distribution of latency amongst the network components that make up the network configuration.

The Latency Graphs can be copied to the clipboard in bitmap format.

Note: The last network configuration you worked on is automatically saved and then restored next time you run the Network Calculator.


Setting Up a Series of Networks

The Network Setup panel starts out with an unknown topology network button between Node A (the desktop computer) and Node B (the tower computer).

Positioning Network Buttons

Nodes A and B are fixed in position and cannot be moved.  All other network buttons can be moved around within the Network Setup panel by dragging them with your mouse’s cursor.

Network buttons may be moved left or right in order by using the left and right arrow buttons.  Moving a network button left corresponds to moving it closer to Node A while moving a network button right moves it closer to Node B.

Inserting Network Buttons

The Insert Network button inserts a new unknown topology network button BEFORE the currently selected network.  The currently selected network is the last network that you clicked and is marked by a dark outline around the button and a dotted line around the image on the button.  Inserting a network can be also be done by right clicking anywhere on the Network Setup panel and selecting the Insert Network menu item.

Changing Network Properties

To change a network button's Topology, Bandwidth, or Propagation Delay, right click on a network button and select Properties... from the popup menu.  Nodes A and B have Packet Size and Processing Delay properties, which can be modified in the same manner.  For example, changing the original unknown network topology to Ethernet will model the simplest case of two nodes attached to a shared Ethernet.

Removing Network Buttons

You may remove a network button by right clicking on it and selecting the Remove menu item.  Another way to remove a network button is to right click anywhere in the Network Setup panel and select a network button from the Remove Network sub-menu.  The currently selected network will show up in bold text.  There must be one network in the setup panel at all times, so you are unable to remove the last network button.

The Reset Layout button removes all networks from your configuration by resetting to the original default layout.