Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 847
  • Last Modified:

TCP/IP Subneting question

I have a network with several branches.
1 network with: 10.10.3.0
2nd network with 10.10.6.0 till 10.10.9.0
3 network with 10.10.10.0
What subnet can I use in order the network 2 will be isolated. That mean network 1 and 3 won't be able to see network 2?
0
Sharoness
Asked:
Sharoness
  • 3
  • 2
  • 2
  • +2
4 Solutions
 
xRalfCommented:
Hello Sharoness,

do you mean what subnet mask to use?

Regards,

xRalf
0
 
SharonessAuthor Commented:
yes
0
 
xRalfCommented:
255.255.255.0
0
IT Degree with Certifications Included

Aspire to become a network administrator, network security analyst, or computer and information systems manager? Make the most of your experience as an IT professional by earning your B.S. in Network Operations and Security.

 
fwetzlerCommented:
I hope, I understood your question ....
you have 3 subnetted class C networks in the class a range:
1) 10.10.3.0                        (Class C subnetted, Mask=255.255.255.0?)
2) 10.10.6.0 - 10.10.9.255  (Class C subnetted, Mask=255.255.252.0?)
3) 10.10.10.0                      (Class C subnetted, Mask=255.255.255.0?)

Now you want to "couple" network 1 and 3, without interacting possibility of network 2?

OK, in this case you can't handle it with a subnetmask. this is only possible with a router, because the range of network 2 lies between network 1 and network 3.
nowadays a good switch is layer 3 capable and has the possibility of building VLANS ....

If a router is not possible, try to put network 3 on range 10.10.4.0 (255.255.255.0) instaed of 10.10.10.0.
Then you can use a subnetmask 255.255.251.0 for network 1 and network 3. In this case Network 2 is "isolated" ...

good luck
0
 
xRalfCommented:
Maybe fwetzler is right.

I haven't read it carefully and thought that
2nd network with 10.10.6.0 till 10.10.9.0 are actually two networks.

But is the subnet mask 255.255.251.0 possible?
0
 
fwetzlerCommented:
uuups, sorry, 255.255.251.0 is not possible.  only  254, 252 or 248 for supernetting 2, 4 or 8 Class C subnets.
is it possible to swich the adress range of net 1 or net 3?
then you can use 255.255.254 for both nets, and 255.255.255.252 for the net 2 ...

sorry ...
0
 
edster9999Commented:
To isolate the 2nd range you need to set the mask to just cover those IP addresses

1 network with: 10.10.3.0
2nd network with 10.10.6.0 till 10.10.9.0
3 network with 10.10.10.0

The problem is your number fall between the valid ranges.

If you use the mask 255.255.254.0
this is too small and gives you
10.10.6.1 - 10.10.7.254
and
10.10.8.1 - 10.10.9.254

if you use the next bigger one (255.255.252.0)
the size is big enough as it covers 4 3rd digit ranges but the boundaries have to stay the same for these.  You can not move them so the ranges would be
10.10.4.1 - 10.10.7.254
and the next range up would be
10.10.8.1 - 10.10.11.254
which is no good as it covers the .10. one you already have.

So the problem here is you always go across two boundaries or two ranges.  You only get this 2nd network into one range if you go up as far as 255.255.240.0
but this then includes all your networks :
10.10.0.1 - 10.10.15.254

So can you make network 2 smaller ?   Does it really need  762 addresses ?
If you can bring it down to
10.10.6.1 - 10.10.7.254
giving you 508 addresses

Then your masks are

1 : 10.10.3.0 / 255.255.255.0 giving 10.10.3.0 - 10.10.3.254
2 : 10.10.6.0 / 255.255.254.0 giving 10.10.6.1 - 10.10.7.254
3 : 10.10.10.0 / 255.255.255.0 giving 10.10.10.0 - 10.10.10.254

If you really can not shorted range 2 you need to move people downwards
to the 4 and 5 ranges as well as the current 6 and 7 ranges and use the mask
2 : 10.10.4.0 / 255.255.252.0 giving 10.10.4.1 - 10.10.7.254

0
 
kdearingCommented:
A .252 mask won't work on net2 because it includes 10.10.8.0 & 10.10.9.0

You have a couple of basic design problems:
    First is the subnetting issue you've already identified.
    Second, Net2 is really too big. It should be segmented.

Although not the easiest, your best solution is to re-design Net2.
  Carve it up by function (accounting, sales, etc) or by locale (bldg1, bldg2, floor1, floor2, etc) into subnets no larger than a Class C (255.255.255.0).
0
 
SharonessAuthor Commented:
Thanks guys, I really appritiate it. i think i will use Vlans.... i just have to get my boss to approove the purchase.

Thank so much
0

Featured Post

IT Degree with Certifications Included

Aspire to become a network administrator, network security analyst, or computer and information systems manager? Make the most of your experience as an IT professional by earning your B.S. in Network Operations and Security.

  • 3
  • 2
  • 2
  • +2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now