Ethernet Segment (ES): When a customer site (device or network) is connected to one or more PEs via a set of Ethernet links, then that set of links is referred to as an ‘Ethernet segment’.
Ethernet Segment Identifier (ESI): A unique non-zero identifier that identifies an Ethernet segment is called an ‘Ethernet Segment Identifier’. ESI 0 denotes a single-homed site. ESI {0xFF} (repeated 10 times) is known as MAX-ESI.
Ethernet Tag: An Ethernet tag identifies a particular broadcast domain, e.g., a VLAN. An EVPN instance consists of one or more broadcast domains.
Ethernet Tag ID: 32-bit field containing either a 12-bit or 24-bit identifier that identifies a particular broadcast domain (e.g., a VLAN) in an EVPN instance.
EVI: An EVPN Instance spanning the Provider Edge (PE) devices participating in that EVPN.
