LinuxQuestions.org
View the Most Wanted LQ Wiki articles.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Networking
User Name
Password
Linux - Networking This forum is for any issue related to networks or networking.
Routing, network cards, OSI, etc. Anything is fair game.

Notices

Reply
 
Search this Thread
Old 11-16-2003, 01:38 PM   #1
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Rep: Reputation: 30
Is there freeware Network Simulation software?


I was wondering if there is some sort of a freeware program to help with learning about networks... I have seen such programs for electronic circuits but couldnīt find anything. I am having problems understanding exactly how to use subnet masks and then calculate how many hosts you could have with the mask even though I have read quite a few articles which are supposed to explain it.

Any Ideas?
Adam
 
Old 11-16-2003, 01:46 PM   #2
jcookeman
Member
 
Registered: Jul 2003
Location: London, UK
Distribution: FreeBSD, OpenSuse, Ubuntu, RHEL
Posts: 417

Rep: Reputation: 33
There are IP calculators...just google ip calc and you will find tons of them.

If you want to know how many hosts you can have with a given netmask then take the count the number of bit positions with corresponding zeros represented by 'n', raise two to that number and subtract '2':

255.255.255.224
=
11111111.11111111.11111111.11100000 (five zeros)
=
2^5 - 2 (raise 2 to the number of zeros - 2)
=
32 - 2
=
30
 
Old 11-16-2003, 02:01 PM   #3
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
THANKS A LOT

Thanks for that wicked explaination I have read lots of things similar but your explaination was what I need to understand how to calculate it easily!

Subtract 2 because the the last is the broardcast address??? and I canīt remember what they first number would be??


Do you have a similar explaination for number of Physical Segments?

Adam

Last edited by jimdaworm; 11-16-2003 at 02:03 PM.
 
Old 11-16-2003, 02:40 PM   #4
jcookeman
Member
 
Registered: Jul 2003
Location: London, UK
Distribution: FreeBSD, OpenSuse, Ubuntu, RHEL
Posts: 417

Rep: Reputation: 33
To do the number of networks it is the exact opposite. Instead of using the number of zeros you use the number of ones. And you don't subtract two, but that depends on if you are doing classfull or classless ip addressing. I will use classless since that is what everyone uses nowadays. Read up on RFC1519.

Take class of address:
First octet rule -
0-127 Class A Default Netmask 255.0.0.0
128-171 Class B Default Netmask 255.255.0.0
127-223 Class C Default Netmask 255.255.255.0

Number of bits subnetted:
IPADDR=10.0.0.0
NETMASK=255.255.0.0

Default netmask since the IPADDR starts with 10 would be 255.0.0.0
Therefore, you borrowed 8 bits to get the 255.255.0.0.

2^8 =
256 subnets possible
 
Old 11-18-2003, 03:02 PM   #5
jimdaworm
Member
 
Registered: Aug 2003
Location: Spain
Distribution: Ubuntu
Posts: 888

Original Poster
Rep: Reputation: 30
Thanks again

Hey this second reply was a little less straigt forward for me but I am off to Read up on RFC1519!!

So impressed by your reply I have printed out this topic!

Thanks
Adam
 
Old 10-19-2006, 01:36 AM   #6
rapatista
LQ Newbie
 
Registered: Oct 2006
Posts: 2

Rep: Reputation: 0
Quote:
Originally Posted by jcookeman
To do the number of networks it is the exact opposite. Instead of using the number of zeros you use the number of ones. And you don't subtract two, but that depends on if you are doing classfull or classless ip addressing. I will use classless since that is what everyone uses nowadays. Read up on RFC1519.

Take class of address:
First octet rule -
0-127 Class A Default Netmask 255.0.0.0
128-171 Class B Default Netmask 255.255.0.0
127-223 Class C Default Netmask 255.255.255.0

Number of bits subnetted:
IPADDR=10.0.0.0
NETMASK=255.255.0.0

Default netmask since the IPADDR starts with 10 would be 255.0.0.0
Therefore, you borrowed 8 bits to get the 255.255.0.0.

2^8 =
256 subnets possible

Hi,

There are 2 different approach in IP adressing i think. One says that B Class is between 128-191 and other is as u say 128-171. Which one is right?
 
Old 10-19-2006, 03:53 AM   #7
jcookeman
Member
 
Registered: Jul 2003
Location: London, UK
Distribution: FreeBSD, OpenSuse, Ubuntu, RHEL
Posts: 417

Rep: Reputation: 33
Quote:
Originally Posted by rapatista
Hi,

There are 2 different approach in IP adressing i think. One says that B Class is between 128-191 and other is as u say 128-171. Which one is right?
Class 'A' networks are 0-127 in the first octet defined bitwise:

0xxxxxxx

Class 'B' networks are 128-191 in the first octet defined bitwise:

10xxxxxx

Class 'C' networks are 192-223 in the first octet defined bitwise:

110xxxxx

Therefore, it must be this way. No other scheme.

Cheers,

Justin

Last edited by jcookeman; 10-19-2006 at 03:58 AM.
 
Old 10-20-2006, 07:44 AM   #8
rapatista
LQ Newbie
 
Registered: Oct 2006
Posts: 2

Rep: Reputation: 0
Quote:
Originally Posted by jcookeman
Class 'A' networks are 0-127 in the first octet defined bitwise:

0xxxxxxx

Class 'B' networks are 128-191 in the first octet defined bitwise:

10xxxxxx

Class 'C' networks are 192-223 in the first octet defined bitwise:

110xxxxx

Therefore, it must be this way. No other scheme.

Cheers,

Justin

Well actually i agree with this one already but;


Quote:
Originally Posted by jcookeman
To do the number of networks it is the exact opposite. Instead of using the number of zeros you use the number of ones. And you don't subtract two, but that depends on if you are doing classfull or classless ip addressing. I will use classless since that is what everyone uses nowadays. Read up on RFC1519.

Take class of address:
First octet rule -
0-127 Class A Default Netmask 255.0.0.0
128-171 Class B Default Netmask 255.255.0.0
127-223 Class C Default Netmask 255.255.255.0

Number of bits subnetted:
IPADDR=10.0.0.0
NETMASK=255.255.0.0

Default netmask since the IPADDR starts with 10 would be 255.0.0.0
Therefore, you borrowed 8 bits to get the 255.255.0.0.

2^8 =
256 subnets possible
u say "128-171 Class B" i didnt understand this one. Also i found this spesification in some other sources (very few). What is the point of this spesification?

Thanx again
 
Old 10-20-2006, 08:06 AM   #9
jcookeman
Member
 
Registered: Jul 2003
Location: London, UK
Distribution: FreeBSD, OpenSuse, Ubuntu, RHEL
Posts: 417

Rep: Reputation: 33
Quote:
Originally Posted by rapatista
Well actually i agree with this one already but;




u say "128-171 Class B" i didnt understand this one. Also i found this spesification in some other sources (very few). What is the point of this spesification?

Thanx again
I was drunk when I posted that. Obviously, I made a typo, but I don't remember as it was quite long ago.
 
  


Reply

Tags
ip


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
C simulation shegay18 Programming 4 06-14-2005 07:49 AM
Network Inventory and Software Distribution Software? tonyfreeman General 1 09-25-2004 05:29 AM
Ossiloscope simulation software... TanelValdna Linux - Software 3 09-09-2004 01:28 PM
Architectural Acoustics Simulation Software carboncopy Linux - Software 0 07-19-2004 10:11 PM
Simulation progam AquamaN Programming 2 03-15-2004 07:26 PM


All times are GMT -5. The time now is 05:17 AM.

Main Menu
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration