Using hte same IP Adresses at multiple sites during move / "Extended LAN"

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Oct 15th, 2002
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A customer has two datacenter sites A and B connected over a corporate WAN.

Site A is using IP-range IPA, B is using range IPB.

Both sites will be moved to a new site C, the IP-range is not yet decided.

Is it possible to make the move activities more flexible, to extend the LAN of site A and site B to site C during the move (site C will be connected to A and B, either via the corporate WAN or a separate leased line)? The idea is to use the ranges IPA and IPB in site C and to avoid changing all IP-adresses. At the same time the ranges will still be in use at sites A and B, but individual IP-addresses will NOT overlap!!! The move will not be done in one day or weekend, but some months.

After the move, sites A and B will disappear.

I heard of a technology called "LAN extension", but could not find something on the Cisco Web.

Anyone any idea how to do this?

Thanks a lot in advance!

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eberte.2001 Tue, 10/15/2002 - 07:01
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I suggest you use VLan to configure new site C. You will have 3 VLan that routing traffic. Don't forget to configure default gateways for each VLan in your switch router. You may reconfigure machines in each VLan after moved.

c.zamecnik Tue, 10/15/2002 - 07:09
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Thanks a lot. But can I use the same IP's in this scenario? This is the primary requirement...

And one important thing I forgot to mention is, that site B can only be connected to (new) site C over a WAN-Link: B and C are on distant ends of the globe...

Sorry for not writing this in the first place....

Meanwhile, I came with one of the following possibilities:

1) Bridge IP only

2) Use a "Double NAT" configration between sites

3) Configre a GRE tunnel

Any comments?


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