The following terms are important for understanding virtual port extenders
- Bridge Port Extenders (BPEs)— Devices
that do not fully process packets, nor make forwarding or filtering decisions. Instead, BPEs
simply receive packets from extended ports and forward packets towards the upstream controlling
bridge for L2/L3 processing.
- Cascade port—a port on a controlling
bridge or BPE that connects to an upstream port.
- Controlling Bridge (CB)—In this
context, a switch that provides full L2/L3 packet processing and filtering functionality for
cascade ports and extended ports.
- E-Channel-ID (E-CID)—Identifies the
BPE destination port (or port-list for multicast E-CID).
- E-Tag—A tag header immediately
following the 802.1BR EtherType (0x893F) that contains the E-CID; this tag is only resident
between bridge port extenders and controlling bridge devices.
- Edge Control Protocol (ECP)—Provides
basic acknowledgement and re-transmission mechanism for reliable delivery; used for PE-CSP
- Extended bridge—A controlling bridge
combined with one or more BPEs.
- Extended ports—Ports from BPEs
connected to the rest of the network.
- Port Extender Control and Status Protocol
(PE-CSP)—Simple command/response protocol that allows a controlling bridge to discover,
program, and obtain status from a bridge port extender.
- Upstream port—Port on a BPE that
connects to a cascade port.
- Virtual Port Extender (VPEX)—A
switching architecture based on the IEEE 802.1BR
specification, comprising a CB, and one or more BPEs.