Copyright: Copyright ¸ Anthony Johnston 1997
Citation: The IP Network Address Assistant


Contents
The IP Address Assistant - Contents

What is The IP Address Assistant?

What Does The IPAA Look Like?

How Do I Enter an IP Address?

How Do I Navigate through the IP Address Assistant?

What Does The OSPF Summaries Page Do?

IP Version 4 Addressing

License Agreement

Bibliography

System Requirements

Revision Details and Bug Reports

How To Contact The Author

Unimplemented Features


What is The IP Address Assistant?

The IP Address Assistant (IPAA) is a Windows 95 program which enables the manipulation of

(TCP) IP Version 4 and OSPF network addresses.

You can use the IPAA to help you further SubNet any given IP V4 address.

The IPAA performs a series of calculations on your IP Address and provides you with the

following information:-

1) A list of SubNet masks applicable to the IP Address entered to enable you to further SubNet your IP Address.

2) A list of IP SubNets generated using your IP Address and mask combination.

3) The first and last valid IP Addresses you can use on each SubNet.

4) The binary and decimal values of the broadcast address for each IP SubNet you have selected.

5) The binary and decimal values of the generated Subnet Address.

6) Identification of the IP class bits used in your IP Address.

7) Identification of which bits are the Network bits and which are the Host bits for your Address.

8) When used with OSPF networks a suggestion of which network address and mask to use to summarise network advertisements.

The IPAA Will generate IP SubNet addresses which utilise the "Zero SubNet" address.

Whilst this the use of this SubNet was originally discouraged its use has recently been permitted.

You should however, be aware that some equipment may not support the use of this SubNet.

It is your responsibility to ensure that you either refrane from using these SubNets or that the IP

systems you use are able to support SubNet Zero


SubNets
SubNets (when referring to IP based networks) are a mechanism used to increase the control you have over an IP address space.

An IP SubNet is a collection of IP addressable objects which have a common network ID.

Thus the following IP Addresses:- 200.1.1.23, 200.1.1.60, 200.1.1.98 assuming you have used a net mask

of 255.255.255.0 all have a SubNet Id of 200.1.1.0.


Broadast Address
This display represents the decimal and binary values of the broadcast address for the subnet

currently highlighted


How Do I Enter an IP Address?

At the top of the main form there are a series of four edit boxes in which you

should enter the IP address you wish to SubNet

Each edit box contains enough space for you to enter one portion of your

IP address which must fall between the numbers 0 to 255 inclusive.

If you enter any other characters the background of the edit box will turn RED

and you must then erase any numbers you have entered and re-input valid data.

Pressing the TAB key will validate the digits you have entered into the edit box

and if these digits are accepted the cursor will be positioned over the next edit box.

Pressing TAB whilst in the last edit box will display the initial results of the

IPAA calculations.


How Do I navigate through the IP Address Assistant?

The IPAA presents you with a single Windows 95 form but with a number of Tabbed Pages

which are used to present you with the information you have requested.

You should first enter the IP Address you wish to sub-net in the four edit boxes at the

top of the form.

For example if you had entered 100 1 1 1 as your IP address in the four edit boxes

the display would look something like this:-

The following information is displayed:-

o The IP class of the entered address

o A representation of the address in binary (beneath the edit boxes) which shows the Network and Host

   bits of the IP Address entered.

o A list of SubNet masks are also displayed which are applicable to the class of IP address entered.

o An indication of the bits of the IP Address used to identify the class of the IP Address entered

If you wish the IPAA to generate a list of valid Sub Nets for this address you have two three ways of doing this:-

1) By selecting a SubNet mask specified in the SubNet Masks listbox.

2) By specifying the number of hosts you need per SubNet.

3) By specifying the number of SubNets you need.

Selecting either 2 or 3 will result in a SubNet mask being higlighted in the listbox, you should then click this

selection.

The IPAA will then display the "SubNet & Address Ranges" page:-

The following additional items of information are now displayed including:-

•	The SubNet Mask Used.

•	A list of valid sub nets generated using your input address and SubNet Mask.

•	The number of valid Sub Nets

•	The number of valid host addresses for each of these Sub Nets

If there are more than 7 valid sub nets a vertical scroll bar will be displayed and you can use this

to display the additional sub nets by selecting the horizontal bar in the scroll bar with the mouse

and dragging it down the bar.

If a large value SubNet mask - such as 255.255.255.224 is used (which could in certain circumstances

result in 16 million sub nets) then an additional control will appear directly under the Sub Nets listbox which

will display the valid sub nets in groups of 5,000. (This could take some time to scroll through all of the possible

combinations of valid addresses).

When you are sub netting an IP address you are in effect borrowing bits from the host portion of the IP address to use as additional

network bits, the IPAA displays the number of ADDITIONAL SubNet bits you have borrowed together with the remaining Host bits

If you wish to obtain further information about the possible range of valid IP addresses for any particular subnet

you should select one of the Sub Nets by clicking one of them with the left mouse button  the IPAA will then display the

following information:-

As you can see in this case SubNet 100.12.0.0 has been selected. The IPAA then displays the value of the

first and last valid IP Address you can use on this SubNet together with the SubNet Directed Broadcast address

for the SubNet. This value is displayed in both Dotted Decimal Notation and as binary.


Host

In TCP/IP terms you can consider a host to be a PC, Mini or Mainframe computer

(although this definition is very loose),and is usually used to contrast facilities offered

between a router and a host.

The host does not partake in routing TCP/IP packets through the network. However a host initially "decide"using its own IP address and Sub Net mask if it needs to request the services of a specialised IP router to forward a packet to any particular destination.


SubNet Mask used
When you have selected a SubNet mask from the list of valid masks these controls

will display the value in decimal and binary of the mask you have chosen


SubNet Mask

A SubNet Mask is a series of Binary Ones which is used to overlay an IP address to enable the remaining host bits of the IP Address to be further sub divided into additional networks.


Base Subnet
These controls represent the binary and decimal values of the IPAA generated subnet address


Unimplemenented Features
The Following features are not implemented in version 1.1 of the IPAA:-

1) Printing Support (If enough people want printing support I'll include it).

2) Variable Length SubNet Masks, although a companion program The VLSM Assistant does provide help in using VLSM


IP Address

An IP (or commonly known as a TCP/IP) address consists of a series of 4 sets of digits separated by a period. Each in series of digits must be in the range of 0-255 (when expressed in decimal).Together they represent the unique address of an object on an IP network such as  100.20.34.45

There are 5 classes of IP address Class A, Class B, Class C, Class D and Class E, however only the first three classes A, B and C are usefull for addressing purposes within most organisations.


What Does The OSPF Summaries Page Do?

This page of the IPAA suggests a suitable network mask to use when summarising

a range of OSPF addresses.

If you select the OSPF Summaries page the following is displayed:-

The two edit boxes enable you to specify the IP SubNet addresses you wish to summarise. Addresses should be entered as complete addresses separated by periods.

Pressing tab will take you from one field to the other.

Once you have entered both SubNet addresses the IPAA will then display the following page

The Network address and suggested mask are now displayed.


System Requirements

An IBM PC or compatible that meets Microsoft Windows 95 requirements.

Microsoft Windows 95.

A mouse or other pointing device.

Two Megabytes of free disk space

It is recommended that you have at least 8 megabytes of free memory available.

This is due to the potentially large number of SubNets which can be generated using certain SubNet mask combinations.

I have been unable to test this product on Windows NT, I have no reason to believe that it won't work but if someone does

try it out I would appreciate it they let me know what the result is together with the system configuration details.

Thank You


Number of SubNets Topic
If you already know the number of SubNets you wish to generate you should specify that number here.

The mask you need to use will then be highlighted.


NumberOfHosts
This area displays the maximum number of valid available hosts on each of the generated Subnets.


What Does The IPAA Look Like?
When you start the IP Address Assistant the following image is displayed:-

The four edit boxes are used to enter the four sets of digits if the IP address you

wish to SubNet

If you click the left mouse button over the above areas of these forms you can get additional

explanations of each of those areas.

The following page is displayed after you have entered the information needed and selected

a net mask:-


IP Version 4 Addressing

The IPAA deals only with IP Version 4 (or 32 bit) addressing. As an explanation of IP addressing

is beyond the scope of this help system I have included references to a number of RFC's which deal

with some of the issues surrounding IP V4 Addressing and routing.

These include:-

RFC1700 S

    J. Reynolds, J. Postel, "ASSIGNED NUMBERS", 10/20/1994. (Pages=230)

    (Format=.txt) (Obsoletes RFC1340) (STD 2)

RFC1627 I

    E. Lear, E. Fair, D. Crocker, T. Kessler, "Network 10 Considered Harmful

    (Some Practices Shouldn't be Codified)", 07/01/1994. (Pages=8)

    (Format=.txt)

RFC1597 I

    Y. Rekhter, R. Moskowitz, D. Karrenberg, G. de Groot, "Address Allocation

    for Private Internets", 03/17/1994. (Pages=8) (Format=.txt)

RFC1520  I

    Y. Rekhter, C. Topolcic, "Exchanging Routing Information Across

     Provider Boundaries in the CIDR Environment", 09/24/1993.

     (Pages=9) (Format=.txt)

RFC1519  PS

     V. Fuller, T. Li, J. Yu, K. Varadhan, "Classless Inter-Domain

     Routing (CIDR): an Address Assignment and Aggregation Strategy",

     09/24/1993. (Pages=24) (Format=.txt) (Obsoletes RFC1338)

RFC1518  PS

     Y. Rekhter, T. Li, "An Architecture for IP Address Allocation with

     CIDR", 09/24/1993. (Pages=27) (Format=.txt)

RFC1517  PS

     R. Hinden, "Applicability Statement for the Implementation of

     Classless Inter-Domain Routing (CIDR)", 09/24/1993. (Pages=4)

     (Format=.txt)

RFC1219 I

    P. Tsuchiya, "On the Assignment of Subnet Numbers", 04/16/1991.

    (Pages=13) (Format=.txt)

RFC0950 S

    J. Mogul, J. Postel, "Internet standard subnetting procedure", 08/01/1985.

    (Pages=18) (Format=.txt) (STD 5)

RFC0940

    Gateway Algorithms and Data Structures T, "Toward an Internet standard

    scheme for subnetting", 04/01/1985. (Pages=3) (Format=.txt)

RFC0936

    M. Karels, "Another Internet subnet addressing scheme", 02/04/1985.

    (Pages=4) (Format=.txt)

RFC0932

    D. Clark, "Subnetwork addressing scheme", 01/01/1985. (Pages=4)

    (Format=.txt)

RFC0917

    J. Mogul, "Internet subnets", 10/01/1984. (Pages=22) (Format=.txt)

It is advisable to check for the latest RFC's for a fuller picture of routing - many sites on the Internet now

carry the copies of all RFC's


NumberOFSubNets
This area shows the maximum number of subnets avaiable using your IP Address/Net mask combination.


SubNet Mask List
A list of valid SubNet masks for you IP Address is displayed here, selecting one of them will

display the "SubNet & Address Ranges" page of this display.


Number of Hosts Topic
If you already know that you require a specific number of hosts on each subnet you should specify the number required here.

The mask you need to use will then be highlighted.


Revision Details and Bug Reports

The current version of  the IPAA is V1.1

This version is the first public release of the product and contains no reported bugs.

That is to not to say that there are no"undocumented features" in this software.

If you do find one of these features please mail the following information to:-

 Anthony@teamvall.demon.co.uk

If you are reporting a problem with IPAA, please provide the following information:

•	The version number (ie IPAA, version 1.1).

•	Your name and e-mail/snail mail address  .

•	Your hardware and software configuration.

•	A description of the problem, and what you were trying to do when the problem occurred.

You must also include the IP address(es) and SubNet Mask you were using.

Thank You


The VLSM Assistant

This is a companion program which enables an IP network designer to have a much greater degree of flexibility of the use of assigned IP SubNet addresses.

The use of a single subnet mask as practised using standard IP subnetting techniques (& of course the IPAA) for the entire network restricts flexibility particularly when the range of available IP addresses is limited.

Suppose that you had been allocated a Class C address by your ISP but you need to connect a number of hosts and locations to the Internet using this subnet address. It is of course possible to  further subnet this address by using standard IP subnetting techniques (or by using the IPAA).

Each SubNet you create from this address must have the same number of hosts regardless of the actual number hosts you plan to install on the SubNets, this leads to an inefficient use of IP addresses and probably doesn't fit with your requirements.

However by using Variable Length SubNet Mask (VLSM) techniques you can have differing number of hosts per SubNet and free up IP address space resource for use elsewhere in your organisation.

Designing VLSM networks can be very cumbersome (and prone to errors) as by necessity VLSM techniques involve the use of non byte aligned Net Masks, and, unless your binary arithmetic is excellent, you need the VLSM Assistant - a tool which takes the pain out of VLSM.

By using a graphical (Windows 95) interface and few clicks of the mouse you can generate VLSM configurations in minutes - be the envy of major governments! - show your boss how clever you are!

The following is screen shot of the development version of the VLSM Assistant to illustrate its use with a Class B IP Address - if you click on portions of the picture further explanation of the features of the VLSM will be displayed.

The VLSM Assistant is not freeware - it is shareware and further details can be obtained by contacting the author of the IPAA.

Please note as mentioned earlier this is a picture of the development version of the VLSM Assistant (as at June 1997). I cannot guarantee that the production version of the VLSM Assistant will look exactly like this screen shot.


VLSMNetworkDetails
This is a summary of the Network you wish further SubNet using VSLM techniques. It shows the initial IP Address and the Net mask initially chosen


VLSMGeneratedSubNets
This is an hierarchical display of the valid subnet addresses the VLSM Assistant has generated using your input IP address and initial subnet mask combination. Selecting one of these SubNets will result in the list network masks, displayed in the "Available SubNet Masks" area being updated to reflect the new set of valid network masks. Selecting one of the network masks by dragging and ropping it onto the one these SubNets will enable you to further SubNet your network.


VSLMNetMasks
This area shows the valid network masks for each of the SubNets selected in the "Generated Addresses" area. Only those network masks which are valid for each SubNet are displayed, thus this display will change depending on which IP Address is slelected in the "Generated Addresses Area"


VSLMEngineering
This item shows the name given to this SubNet, together with the network mask to use. Also listed are the first and last valid IP Addresses on this subnet together with the subnet directed broadcast address


Input Address Information
These four edit boxes should be used to enter the IP Address you wish to Sub Net Also displayed are the IP class bits together with a binary representation of the host and network bits of the IP Address.


Licence Agreement

If you use the IPAA you agree to be bound by the following license agreement:-

IP Address Assistant

Copyright © 1997 Anthony Johnston

THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED

WARRANTIES OF MERCHANTABILITY AND FITNESS, AND IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM

LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER

ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

Permission to use, copy, and distribute this software and its documentation for any purpose other than its commercial

exploitation is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that

copyright notice, disclaimer, and this permission notice appear in supporting documentation, and that the name of author

not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission.

The author makes no representations about the suitability of this software for any purpose. It is provided "as is" without expressed

or implied warranty.


How To Contact The Author
The author welcomes comments/suggestions regarding this program and you may contact him at the following email address:-

Anthony@teamvall.demon.co.uk

or via snail mail at

     2 Deneside Avenue

     Low Fell Gateshead

     Tyne & Wear

     NE9 6AD

     UK


Bibliography

I have found the following books very helpfull in obtaining an understanding of the issues surrounding IP addressing and SubNetting. However as all reccomendations are subjective please inspect these books to make sure that they are what you require.

Title:	TCP/IP Running a Successful Network

Author(s)	K. Washburn & J.T. Evans.

Publisher	Addison-Wesley

ISBN	0-201-62765-5

Title	TCP/IP Illustrated Volume 1 The Protocols

Author(s)	W. Richard Stevens

Publisher	Addison-Wesley

ISBN	0-201-63346-9

Title	TCP/IP Addressing - Designing and Optimizing Your IP Addressing Scheme

Author(s)	Buck Graham

Publisher	Academic Press Ltd

ISBN	0-12-294630-8

Title	Routing In The Internet

Author(s)	Christian Huitema

Publisher	Prentice Hall

ISBN	0-13-132192


GeneratedSubnets
This listbox contains a list IP SubNets which have been generated by the IPAA if you select one of them additional information is displayed


IP Classes

Each IP Address has a degree of hierarchy associated with it, with the first binary digits being used to identify the Class of the IP address.

The following table illustrates the typing of IP Classes:-

Class	1st Address	Last Address	Class Value	No Of Network Bits	Max Hosts/Network

A	1	126	0XXX	7	16,777,216

B	128.1	191.254	10XX	14	65,536

C	192.0.1	223.255.254	110X	21	256

D	224.0.0.0	239.255.255.254	1110	None	Not Applicable

E	240.0.0.0	255.255.255.254	1111	None	Not Applicable

Class Value indicates the value of the first few binary digits in the first series of IP address digits.

There are a number of special cases of IP addresses, specifically address 0 and 127 in the Class A range are reserved address 127 is used for a software loop back test which is essentially a diagnostic device since no IP packet with an address beginning 127.X.X.X should be forwarded by a network adapter onto the network.

Class D addresses are used in Multicasting and Class E addresses are for experimental use only

Note that these values are valid only if not using SubNet-ed addressing the IPAA is used to further break down class A, B or C addresses into Sub Nets