extend subnet (maybe virtually) over WAN, possible ?

[Banibrata Dutta]

Hi,

Wondering if there is some technology/means available where-in, I could have 2 servers which are physically in 2 different data-centres, be somehow configured to share the same subnet ? Could this be possible somehow using an IP-VPN for instance ? Or some kind of a meta-VLAN ?

The underlying technology used to interconnect the 2 data-centres could be carrier-provided/leased MPLS.

Roughly speaking, here's the current physical topology...

Server-1 --- Router-1 --- WAN-Router2 --- WAN-Router3 --- Router-4 --- Server-2

where Server-1, Router-1 are in data-centre#1 using the egde-router (WAN-Router2) to connect to other data-centre hosting the other 3 nodes i.e. WAN-Router3, Router4 and Server-2.

In fact, I'd like to threat at least a pair of servers in data-centre1 and another pair in data-centre2 to be on the same subnet.

So hungup on same subnet, because there's some "IP-address" migration technology which depends on forced ARP-cache update which works only in a subnet. The IP-address (also called floating-IP) migrates from an active-machine to standby in case of failure, and all client-server reconnections happen on the unique floating-IP, which migrates to the newly elected Active node.

cheers,
BDutta

[Banibrata Dutta]

Just to add a bit, the Router-1 and Router-4 are connected to the servers -- Server-1 and Server-2 via an intermediate switch like Procurve E2520 (24port L2 managed switch).