A multi-homed host device is a device that is connected to more than 1 leaf node in a fabric. A host device can create ethernet links to up to two (2) leaf nodes. These links are collectively known as an Ethernet Segment (ES). Each ES is identified by a unique 10-octet hexadecimal identifier known as an Ethernet Segment Identifier (ESI). This ESI is used by the leafs to identify that they are a part of the same ES.
Multi-homing enables maintenance of EVPN services in case of the following types of network failure:
Core Failure - Failure of link between the Leaf and Spine nodes of the Fabric.
Leaf Device Failure - Failure of a Leaf to which the host is connected.
Client Interface Failure - Failure of the link between the host and the Leaf to which the host is connected to.
Note
BGP EVPN Multi-homing is supported on the Extreme 8720, Extreme 8520, SLX 9250, and SLX 9150 platforms. It is not supported on the Extreme 8820, SLX 9740, SLX 9640, and SLX 9540 platforms.