LinuxQuestions.org
Latest LQ Deal: Latest LQ Deals
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 04-04-2006, 10:21 AM   #1
cxy0481
LQ Newbie
 
Registered: Oct 2005
Posts: 11

Rep: Reputation: 0
How to subnet RFC1918 10.190.X.X


Can 10.190.X.X be subnetted? I realize this is a private, Class A network. Not real strong on subnetting, this was the network ID I was given to work with. Looking for maximun subnets, minimal hosts.

Thanks.
 
Old 04-04-2006, 10:41 AM   #2
nx5000
Senior Member
 
Registered: Sep 2005
Location: Out
Posts: 3,307

Rep: Reputation: 57
Its a ClassA subnetted as a ClassB
Maximum subnet, minimal hosts gives:
Netmask 255.255.255.254
=>
16384 net of 2 hosts

Use this for lazy people:
http://www.cotse.com/networkcalculator.html
 
Old 04-04-2006, 10:52 AM   #3
cxy0481
LQ Newbie
 
Registered: Oct 2005
Posts: 11

Original Poster
Rep: Reputation: 0
So subnetting the CLASS A network as a CLASS B is not an issue? That is what I was trying to get straight in my head. I can increase the number of hosts and decrease the number of subnets just by backing down the 4th octet to 252 for example?

Thanks again.
 
Old 04-04-2006, 11:03 AM   #4
nx5000
Senior Member
 
Registered: Sep 2005
Location: Out
Posts: 3,307

Rep: Reputation: 57
I made an error, its 255.255.255.252
252 is :
11111100 , which leaves 00 for hosts (00,01,10,11). You remove 00 and 11 which are the entire network and broadcast so you have 2 machines per subnets
Then you want to have more hosts, you shift to the left
11111000
which is 248 (or /29 in cidr notation)
and gives you 000=3 bits = 8 machines -2 = 6

No its not a problem is CIDR routing. http://www.faqs.org/rfcs/rfc1519.html

The rfc you mention are the address that the internet global router (not your internal, local adress in rfc terminology) will not route. If they receive a packet for this adress (they don't have your netmask, they only look at the prefix:10), they thrash it. Its for security measures.

Last edited by nx5000; 04-04-2006 at 11:06 AM.
 
Old 04-04-2006, 11:53 AM   #5
cxy0481
LQ Newbie
 
Registered: Oct 2005
Posts: 11

Original Poster
Rep: Reputation: 0
Thanks. I'll give it a try.
 
Old 04-06-2006, 11:16 AM   #6
baldy3105
Member
 
Registered: Jan 2003
Location: Cambridgeshire, UK
Distribution: Mint (Desktop), Debian (Server)
Posts: 891

Rep: Reputation: 184Reputation: 184
The "Class" of a network is just a convention. You can in reality subnet a network however you want as long as you are aware of the limitations. 10.0.0.0 is classically a Class A network and would be found with a 255.0.0.0 mask. However you can subnet it however you want as long as you remember that the first address is always the network identifier and the last is always the subnet broadcast address.

If you give 10.0.0.0 a class c mask or 255.255.255.0 then you have 65536 possible subnets of 10.x.x.x each with 256 addresses, but the .0 and .255 addresses are not usable as hosts.

This is why the 255.255.255.254 mask is never used as it gives two addresses, one network and one broadcast and nothing in between. Ooops. 255.255.255.252 gives two usable host addresses, hence why it is used for point-to-point WAN links.

Basically network 10.0.0.0 doesn't exist on the internet, you need to NAT out to the internet so you can pretty much please yourself as long as you maintian a consistent scheme within you network.
 
Old 04-06-2006, 11:45 AM   #7
cxy0481
LQ Newbie
 
Registered: Oct 2005
Posts: 11

Original Poster
Rep: Reputation: 0
subnetting 10.190.X.X

Thanks.

What I did was use 10.190.X.X network, with 255.255.252.0 subnet mask.

Gives me all of the SUBNETS and HOSTS I need. I kept thinking classful addressing vs. classless addressing. Thanks again to all..
 
  


Reply


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
subnet jpostma Linux - Hardware 1 10-16-2005 03:11 PM
another subnet. bruse Linux - Networking 1 07-19-2005 01:35 PM
printer support for Cannon mpc 190 sweet*amber Red Hat 0 05-01-2004 09:10 AM
a /27 within a /24 subnet arnix Linux - Networking 1 07-16-2003 10:16 PM
Can IP from different subnet be configured on another subnet russell Linux - Networking 1 08-23-2002 02:47 AM

LinuxQuestions.org > Forums > Linux Forums > Linux - Networking

All times are GMT -5. The time now is 03:51 PM.

Main Menu
Advertisement
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
Open Source Consulting | Domain Registration