?
Solved

Subnetting_why are these two subnets talking?

Posted on 2007-11-19
10
Medium Priority
?
313 Views
Last Modified: 2012-06-21
Hi.  I expanded my (single - unrouted) network over the weekend by changing the subnet from 255.255.255.0 to 255.255.240.0.  I am fairly new to networking but thought that these were two separate subnets and so would not easily talk to each other.  I'm glad they do as my job was that much easier but why, during the changeover, did devices on each subnet still communicate with each other?  Will I lose connectivity at some point if I missed a subnet change on one of my devices.
0
Comment
Question by:valmatic
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3
  • 2
  • +1
10 Comments
 
LVL 6

Accepted Solution

by:
MorDrakka earned 75 total points
ID: 20313059
Hi,

I think that is the case because the fact the two subnets overlap eachother if you have the same starting IPadress.

Let me explain:

Say at first you have this:

http://jodies.de/ipcalc?host=10.0.0.1&mask1=24&mask2=

And you are migrating to this:

http://jodies.de/ipcalc?host=10.0.0.1&mask1=20&mask2=

If you compare the 2 start hostname's with eachother you see they overlap eachother.

Does this clarify somewhat ?

M


0
 
LVL 7

Author Comment

by:valmatic
ID: 20313307
I understand what you mean about the overlap and that looks like exactly what's happening but I'm still unclear as to why that occurs.  (?)  
0
 
LVL 18

Assisted Solution

by:Johnjces
Johnjces earned 75 total points
ID: 20313478
That is the purpose of subnetting. You can easily allow several sub-networks to talk.

Get an IP calculator. That will show you easily the allowed ranges that can be created using a different IP subnet mask.

Here is a link for an online one:

http://jodies.de/ipcalc

Here is a free one from 3Com:

ftp://ftp.3com.com/pub/utilbin/win32/3CIPCalc.zip

Might help

John
0
Plug and play, no additional software required!

The ATEN UE3310 USB3.1 Gen1 Extender Cable allows users to extend the distance between the computer and USB devices up to 10 m (33 ft). The UE3310 is a high-quality, cost-effective solution for professional environments such as hospitals, factories and business facilities.

 
LVL 7

Author Comment

by:valmatic
ID: 20313508
THanks guys,  Guess that answers my question. :)
0
 
LVL 6

Expert Comment

by:MorDrakka
ID: 20314151
WHAT ? I believe I answered it. Johnices even gives the same link as I do.
0
 
LVL 18

Expert Comment

by:Johnjces
ID: 20314196
MorDrakka

I am so sorry! I did not read your post or I would have not included the online IP Calculator.

The only difference was a direct answer to his question, "...but why, during the changeover, did devices on each subnet still communicate with each other? " with; "That is the purpose of subnetting. You can easily allow several sub-networks to talk."

John
0
 
LVL 77

Expert Comment

by:Rob Williams
ID: 20314674
As an "innocent bystander", I would say MorDrakka deserves a point split as a minimum. If you like you can ask the moderators to re-evaluate in the community support forum.
http://www.experts-exchange.com/Community_Support/General/#browseZones
--Rob
0
 
LVL 18

Expert Comment

by:Johnjces
ID: 20315046
valmatic

I do concur with RobWill!

John
0
 
LVL 7

Author Comment

by:valmatic
ID: 20320252
points split.  
0

Featured Post

Get your Conversational Ransomware Defense e‑book

This e-book gives you an insight into the ransomware threat and reviews the fundamentals of top-notch ransomware preparedness and recovery. To help you protect yourself and your organization. The initial infection may be inevitable, so the best protection is to be fully prepared.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When it comes to security, there are always trade-offs between security and convenience/ease of administration. This article examines some of the main pros and cons of using key authentication vs password authentication for hosting an SFTP server.
This article explains the fundamentals of industrial networking which ultimately is the backbone network which is providing communications for process devices like robots and other not so interesting stuff.
NetCrunch network monitor is a highly extensive platform for network monitoring and alert generation. In this video you'll see a live demo of NetCrunch with most notable features explained in a walk-through manner. You'll also get to know the philos…
Michael from AdRem Software explains how to view the most utilized and worst performing nodes in your network, by accessing the Top Charts view in NetCrunch network monitor (https://www.adremsoft.com/). Top Charts is a view in which you can set seve…

765 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question