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Accessing two identical networks

Unanswered Question
Sep 19th, 2007
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I have the following dilema. I have two private networks with the same subnet e.g. 192.168.0.X.


In each LAN I have several devices with IP addresses 192.168.0.1, 192.168.0.2, 192.168.0.3 and so forth. Currently there is no connection between both LANs.


I need to address devices from both LANs from one station, but changing their IP addresses is not an option.


I need to know what type of equipment do we need to make this happen, if it is a router, a bridge or something else.


Any help would be deeply appreciated.

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Overall Rating: 5 (1 ratings)
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guruprasadr Wed, 09/19/2007 - 06:34
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HI,


If my understanding is not wrong on your Question.


You wanted to make the 2 different identical VLANS to communicate each other.


You need a L3 Capability Equipment to Route the Traffic between the different VLANS in different Subnets.


Since inside LAN, you can go for a L3 Featured CISCO Switch else if the LANS are located in different Branch Office better go for a CISCO Router.


PLS RATE if HELPS


Best Regards,


Guru Prasad R

paul.matthews Wed, 09/19/2007 - 06:43
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You will need routers - two of them. You will need to use NAT to translate the addresses so they look different - make net1 look like 192.168.1.0/24 and net2 look like 192.168.2.0/24 for example, so that within the network they use their local addresses, but outside communication makes them look like something else.

mheusing Wed, 09/19/2007 - 07:10
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  • Cisco Employee,

Hi,


You need a router doing NAT.

The simple reason is: for your host connecting to f.e. 192.168.0.1 in LAN1 and 192.168.0.1 in LAN2 both stations must have unique IP addresses. So the NAT requirement is: 192.168.0.0/24 in LAN1 may be unchanged, but 192.168.0.0/24 in LAN2 has to be translated in a free/unused IP subnet.

There are some documents describing the configuration details, like in "Translating Overlapping Address: Example"

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008044eddc.html#wp1073462

You will find more documents searching for "overlapping address nat" in Cisco search.


Hope this helps! Please rate all posts.


Regards, Martin

jrullan01 Wed, 09/19/2007 - 14:30
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Martin,


Thank you for the prompt reply. I'll follow your sugestion and hopefully solve my problem.



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