Well, I suggest you look at the pictures of the equipment.

Routers and switches are similar.

Let me give you three different examples. You can look at Cisco 2500, Cisco 2600 and Cisco 2800.

There are three corresponding port labels: e1e11e11.

E 1 If you see this, it must be a device with a solidified interface, that is to say, what kind of port on the device has been fixed and cannot be added, deleted or replaced.

E11In this case, everything connected in the slot is just an interface card, that is, the cards you insert are all interfaces one by one.

E111In this case, prove that you are directly connected to a module in the slot, and all other port cards are plugged into this module.

I wonder if you can understand this.