Network Device Terminology Simplified

When you are trying to convey information to an IT person the words Routers, Switches and Radios is probably the second most not understood.  So what is what and what does each type of device do on a network.

Switches and Radios

Small Workgroup Cisco Switch

Small Workgroup Cisco Switch

Physically Switches and Access Points/Radios do the same thing.  Switches are for physical medium like Cat5 wiring (Ethernet).  Radios/Access Points do the same thing as switches but for wireless medium.  Both devices are Layer 2 devices.  So they don’t care about IP addresses only MAC addresses (the physical address of the device) and get network traffic to the correct place.  Consumer routers, Cable Modems, DSL Modems in general have 4 ports of switched access and one or two radios.  In large network deployments these devices are deployed in multiple locations.  Switches run the infrastructure and Access Points deploy traffic wirelessly.

Routers

Small Cisco Router RV320

Small Cisco Router

So what about routers?  Routers separate the outside world from the inside world.  They know in general one thing.  They know the IP Address of where it needs to send traffic that does not belong to them,, and that is called WAN (Wide Area Network which is generally the Internet).  They also know what is on the inside of the network or LAN (Local Area Network).  A computer on the inside of the network will send traffic that is not a LAN address to the router.  The router then decides how to get it to what is called the next HOP.  That next HOP is usually another router.  The process continues until it reaches the router at the destination router which then decides if it can deliver it or not to the final destination.  Most routers these days have a low grade firewall which will apply rules to the incoming traffic.  Most all consumer routers have a basic set of firewall rules which state very simply that everything can be sent out and nothing can be sent in unless it is return traffic.  Cable Modems and DSL Modems are routers that Modulate and Demodulate the signal from DSL provider (phone line) or Cable company (Coax) as well as provide routing.

I hope that this discussion helps somewhat in what the differences are.