Networking Basics

Network basics.
Here’s a real basic run down of network basics because 1)I have noticed a few people using the wrong terminology for some devices on the network 2) I like to hear myself type.
Ok so most modern networks are entirely switched so in all likelihood you won’t see a true hub. So a switch forwards packets based on mac address(layer2). This is a number burnt in to your network card at the factory. When your computer wants something from someone on the same lan it sounds an arp request for the mac address of the resource it wants. If that device is there then all is well and the traffic will flow through the switch. Now if you have to cross networks that is where IP address come in(layer3), a router(sometimes called default gateway) forwards these packets onto the next network. Networks are determined by subnet masks. The most common network for people to be on is 192.168.1.x. 192.168.x.x, are private networks. 10.x.x.x are also private networks as well as 172.16.x.x through 172.31.x.x. If you are on a private network and you can get to the internet then your router is performing NAT. Network Address Translation translates private ip address to public it can do this on a one on one basis. When it does it on a many to one bases this is actually calle PAT (port address translation) this is what most consumer grade routers do. They do this because most dsl/cable companies only a lot you one IP.

Any questions? Just email me.