unit/slot/port Naming Convention

200 Series software references physical entities such as cards and ports by using a unit/slot/port naming convention. The 200 Series software also uses this convention to identify certain logical entities, such as Port-Channel interfaces.

The slot number has two uses. In the case of physical ports, it identifies the card containing the ports. In the case of logical and CPU ports it also identifies the type of interface or port.

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Type of Slots

Slot Type Description
Physical slot numbers Physical slot numbers begin with zero, and are allocated up to the maximum number of physical slots.
Logical slot numbers Logical slots immediately follow physical slots and identify port-channel (LAG (Link Aggregation Group)) or router interfaces. The value of logical slot numbers depend on the type of logical interface and can vary from platform to platform.
CPU slot numbers The CPU slots immediately follow the logical slots.

The port identifies the specific physical port or logical interface being managed on a given slot.

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Type of Ports

Port Type Description
Physical Ports The physical ports for each slot are numbered sequentially starting from one/ For example, port 1 on slot 0 (an internal port) for a stand alone (nonstacked) switch is 1/0/1, port 2 is 1/0/2, port 3 is 1/0/3, and so on.
Logical Interfaces Port-channel or Link Aggregation Group (LAG) interfaces are logical interfaces that are only used for bridging functions.

VLAN routing interfaces are only used for routing functions.

Loopback interfaces are logical interfaces that are always up.

Tunnel interfaces are logical point-to-point links that carry encapsulated packets.

CPU ports CPU ports are handled by the driver as one or more physical entities located on physical slots.


In the CLI, loopback and tunnel interfaces do not use the unit/slot/port format. To specify a loopback interface, you use the loopback ID. To specify a tunnel interface, you use the tunnel ID.