The customer is looking for redundant interconnection of the existing network to the new ACI...

For a redundant interconnection that routes both unicast and multicast traffic, the L3Out (Layer 3 Outside) implementation in Cisco ACI should include the following:

Redundant Connections: Ensure there are at least two connections from the ACI fabric to the external network for redundancy. These connections should be to different leaf switches if possible.

Routing Protocols: Configure a routing protocol that supports both unicast and multicast routing. OSPF or EIGRP can be used for unicast, and PIM (Protocol Independent Multicast) should be configured for multicast.

Route Redistribution: Set up route redistribution between the ACI fabric and the external network to ensure that routes are shared across both networks.

Multicast Configuration: Enable multicast routing within the ACI fabric and configure the necessary multicast policies.

Contract and Policy Configuration: Define contracts and policies that allow the required unicast and multicast traffic to flow between the ACI fabric and the external network.

References :=

Cisco documentation on configuring L3Outs in ACI

Cisco white paper on ACI Multicast Routing