What is a port channel interface, and how does it relate to EtherChannel?

A port channel is the virtual (logical) interface created when physical interfaces are bundled into an EtherChannel.

* Member ports bundled into one port channel. *

EtherChannel was originally developed by Cisco as a LAN (Local Area Network) switch-to-switch technique for grouping several Fast Ethernet or Gigabit Ethernet ports into one logical channel.

Key terminology:

• EtherChannel — the technology/concept of link aggregation
• Port channel — the resulting virtual interface (e.g., Port-channel 1)
• Member interfaces — the physical ports bundled into the port channel

How it works:

• The physical interfaces are bundled together into a port channel interface
• Configuration applied to the port channel automatically applies to all member interfaces
• STP (Spanning Tree Protocol), routing protocols, and other features interact with the port channel, not individual links
• The switch treats the bundle as one logical interface for all purposes

Go deeper:

• EtherChannel Protocols and Configuration (FlackBox) — how the logical port-channel is built from physical members, with SU/P flags.
• What is EtherChannel (Study-CCNA) — the one-logical-link concept and why STP sees the bundle as one link.