Extended Layer 2 over Layer 3 (L2 over L3)

I have a senario where my boss wants to use old 6500 as L3 gateway over a New Layer 3 Core conencting them instead of using 1 gig conenction to 6500- how can i achive this

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Layer 3 Gw- 6500 ( Vlan 100)

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I3

I3

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New 6800 - Core - Layer 3

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I2

I2

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New 9000 - Layer 2 (Vlan 100)

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