is it possible to have the same subnets from one location to another using data link

Zacharia Kurian
Zacharia Kurian used Ask the Experts™
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Our IT department is getting shifted to another location with better equipments. Currently in the head office we have 2 different sub nets using CISCO 1841 router (static IP routes), with non manageable gigabyte switches.

In the new location we will be having L3 & L2 switches (D-Link), and these 2 location will be connected through fiber data link from the ISP. Now my question is, can we have the same sub nets in the branch, which are been used in the head office? For example if in the head office the sub nets are 192.168.2.0/24 and 192.168.3.0/24, can we use these same sub nets in the branch? in way both the location should be on these same sub nets.

If this is possible, what all configurations are required to be done in;

(a) in the  head office 1841 router which is having static routes.
(b) configuration that are to be done in L3 and L2 switches (D-Link) in branch office?
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AkinsdNetwork Administrator

Commented:
Yes it is possible but not common

You will have to setup Dynamic NAT between the two locations.
Your devices will have to communicate using host names when going accross the network.
gt2847cSr. Security Consultant

Commented:
Is there a particular requirement that you have to have the same subnets?  There are more reasons than can be easily enumerated here why you wouldn't want to do this, and very few legitimate reasons for trying it...
Commented:
To use the same subnets on both ends you will need to build a GRE Layer2 Bridge.

http://www.openflow.org/wk/index.php/Tunneling_-_GRE/L2TP
If your ISP will provide you Layer 2 connectivity then yes! I did just this configuration with an AT&T Metro Ethernet connection. It was very simple to manage, but we have 10 sites and more than 800 computers, 800 phones, etc... It got very chatty so I broke them all back out.

I didn't have to build any tunnels or anything, as far as my switches were concerned everything was connected to it via dark fiber...

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