Computer Networks are structured on the basis of a layered protocol and different connecting devices are used at different layers. The TCP/IP protocol of computer networks has 5 layers namely the Physical, Data Link, Network, Transport & Application Layers. The different connecting devices or connectors used in these different layers in computer networks can be summarized by the following table:
| DEVICE | LAYER | CONNECTS | FEATURES |
| Passive Hub | Below physical layer | Wires from different branches | It is just a connector – does not do anything else |
| Repeater | Physical layer | Two segments of the same LAN | Regenerates signals for greater coverage; No filtering – only forwarding & regeneration |
| Active Hub | Physical layer | To extend the same LAN | It is a multiport repeater |
| Bridges | Both physical & data link layer | Connects two different LANs | Has filtering capacity – uses a bridge table to match address to port |
| 2-Layer Switch | Physical & data link layers | Connect many different LANs | Add functionaly to bridges like advanced filtering and multiport capability |
| Router | Physical, data link & network layers | Connects multiple networks of the same protocol stack | Routes packets based on their logical address |
| 3-Layer Switch | Physical, data link & network layers | Multiple networks of same stack | Adds features to routers like faster look up tables & hence, faster forwarding |
| Gateway | All 5 Layers | Connects networks of different protocol stacks | Provides filtering and security |
