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Subnet / network question

Our network is working fine with the following configuration
A NSA SonicWALL - DCHP server with LAN ADDRESS
10.0.0.1
 255.255.254.0

This allows us to use Servers and switches, printers
10.0.0.2    thru     10.0.0.253
and our workstations and laptops
10.0.1.0    thru     10.0.1.253

QUESTION
We are setting up a remote office via a MPLS and I want those machines as
10.0.5.0   thru  10.0.5.253  

PROBLEM  
When attempting to add a custom route in our SonicWall firewall it says
that the 10.0.5.0 / 255.255.254.0    is an INVALID subnet
 
I am NOT a subnet expert don't think  I can learn the math in a day or two.  Any advice appreciated.
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azpete
Asked:
azpete
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4 Solutions
 
cavp76Commented:
For 10.0.5.0 - 10.0.5.253  should be 255.255.255.0 (/24 subnet)
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RKinspCommented:
Bit checking.

254 means that your last significant bit is not part of the subnet, so it cannot be 1. (5 has a 1 on the last significant bit).

Use 10.0.4.0, 255.255.254.0.

Good luck.
-RK
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RKinspCommented:
cavp has it better since you are going with 10.0.5.0 to 10.0.5.254

-RK
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ssisworoCommented:
just convert to binary..
here the example :

                    decimal                    binary
ADDRESS = 10.0.0.1             => 00001010.00000000.00000000.00000001
MASK       = 255.255.254.0   => 11111111.11111111.11111110.00000000
                                                 ------------------------------------------------------
                           your network   00001010.00000000.0000000                         ===> 10.0.0
                           your address                                                   0.00000001      ===>  1


the problem is :

your network               10.0.5.0 => 00001010.00000000.00000101.00000000
MASK                 255.255.254.0 => 11111111.11111111.11111110.00000000
                                                    --------------------------------------------------------
                                                        00001010.00000000.0000010                  
                                                                                                        1 <==== of course this invalid
                                                                                                                     (must be 0)



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cavp76Commented:
Or get a IP/Subnet Mask calculator...Boson Utilities ;)
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ssisworoCommented:
the solution :
1. you can change mask to 255.255.255.0
    ==> so you network area increasingly enlarged and grew smaller address
or
2. you can change network to 10.0.4.0  (remove the '1' in address area)

your network               10.0.5.0 => 00001010.00000000.0000010   |   1.00000000
MASK                 255.255.254.0 => 11111111.11111111.1111111   |   0.00000000
                                                        -----------------------------------    |
                                                               network area                      |
                                                                                                           |   ----------------
                                                                                                           |   address area
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ssisworoCommented:
note :
if you want 2 machines or more to communicate, must be in a network. unless you have a router to bridge between different network.
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