Consider this interface name GigabitEthernet1/0/48

I know that GigabitEthernet is an interface type. What does 1, 0 and 48 stand for?

2 Answers 2


Those are for the slot, subslot and port number.

This is mainly used by (and come from) Cisco routers, which are modular.

Those routers can have different cards inserted into a slot, so the final numbering will depend on the type of card inserted.

From sunsetlearning.com

The first thing you need to remember is the convention: slot#/port#. With this convention it is indicating from less to more specific which port you are referencing. The slot can be the device itself or a slot for HWICs (High-Speed WAN Interface Card) or NMEs (Enhanced Network Module). By default non-modular devices, or switches and routers that have no extra slots for HWICs or NMEs, have only one slot, slot 0. So all interfaces will be in slot 0, such as FastEthernet 0/0 or FastEthernet 0/24. Devices that have expansion slots also have slot 0, that is their built in ports. When you start plugging in modules, they become slots 1,2,3….and so on. So with slot you are indicating where the port is, either on the device, or on a card on the device. Then comes the port number. So if I tell you to go configure port GigabitEthernet 0/23 on a switch, you know that it is a built in port, and it is the twenty-third one in.


It depends on the type of hardware equipment that you use. In most case, it means Number In Stack/Card or Slot / Port . SubInterface (like VLAN or IP SubNet)

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