Which protocol is used to communicate end point mapping information to the spine proxy?

LLDP (Link Layer Discovery Protocol) is used for neighbor discovery on local links, not for exchanging endpoint mapping information across the ACI fabric.

In Cisco ACI, the COOP (Council of Oracles Protocol) is a proprietary control plane protocol used by the leaf and spine switches to communicate and synchronize endpoint mapping information. Leaf switches use COOP to inform spine switches (which act as proxy for unknown endpoint locations) about locally learned endpoints, and spines use it to distribute endpoint information throughout the fabric. This ensures that all devices have a consistent view of where endpoints reside for optimized data forwarding.

OpFlex is a control plane protocol used between ACI controllers (APIC) and network devices (like leaf switches, hypervisors) for policy enforcement and communication, but not for direct endpoint mapping information exchange between leaf and spine switches for forwarding.

IS-IS (Intermediate System to Intermediate System) is an interior gateway routing protocol, not used in ACI for endpoint mapping information exchange between fabric nodes.