Wi-Fi Structures

Types of Wi-Fi Network Products

• Access Point– Radio transceiver

(transmitter/receiver) unit that plugs into a router, switch, or hub on a home network to let wireless clients– your computers – access your wired network (and Internet connection).

Types of Wi-Fi Network Products

• router (gateway)– Shares broadband

Internet connection among all the client PCs on the network.

– Only difference between wired and wireless router is the latter has the access point built in.

Types of Wi-Fi Network Products

• router (gateway), continued...– Built in Ethernet switch allows for

communication between clients, as well. Expect enough Ethernet ports to connect from 2 to 8 computers using Cat 5 cable.

Types of Wi-Fi Network Products

• Wireless Network Interface Cards (NICs)– The adapter that allows a PC to

connect to the access point, and thus talk to the wireless network.

– All shapes and sizes:1. Internal – PC Card (Sometimes called

CardBus) for laptops2. Internal --PCI Card for desktops3. External – USB or Ethernet-to-

Wireless Adapter4. Embedded (non-removable) –

miniPCI, comes with laptop.

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Other Equipment

• Repeaters – used to extend the signal range of a WLAN component.

• Bridge – connects two separate wired or wireless LANs

Basic Home Wi-Fi Network

The Internet AKA the WAN

Cable/DSL Modem

Router

Home PC connected by Ethernet

Access Point

First LaptopSecond Laptop

Second Home PC connected by Wi-Fi

Basic Home Wi-Fi Network (alternate)

The Internet

Cable/DSL Modem

Wireless Router

Laptop

PDA

Home PC via Wi-Fi

Hub or Switch

Home PCs connected by Ethernet

Game Console

Get the LAN Talking

• DHCP– A Dynamic Host Configuration Protocol (DHCP)

server will provide IP addresses to all the computers on the network.

Most routers include a DHCP server to serve a range of addresses.

Get the LAN Talking

• DHCP– Each computer should

be set to be a DHCP client.

– In Windows, set the network card’s settings to “Obtain IP address automatically.”

Get the LAN Talking

• DHCP– The router will typically be your “default

gateway” to the Internet and will provide the IP address indicating that to all clients.

– If your router’s IP address is 192.168.0.1, all computers using 192.168.0.2 to 192.168.0.254 will use that router to access the Internet.

Home Network- IP Addresses

The Internet

Cable/DSL Modem – gets IP from your ISP,

64.185.133.92

Router Gateway for LAN: 192.168.0.1;To Internet appears as 64.185.133.91

192.168.0.100Access Point: 192.168.0.102

192.168.0.104

192.168.0.105

192.168.0.103

Home Networking Tip• “ipconfig”

– If you need to quickly find out the IP address of your computer and the router/gateway, go to a command window and type ipconfig. (winipcfg in Windows 9x)

Get the WLAN Talking• Set up the SSID:

– To connect to an access point, each client must know the Service Set Identifier (SSID) – the name of the wireless network -- of the access point and set that in its configuration utility.

– CHANGE the SSID -- Vendors typically set the SSID of products to a simple, generic name, like the company name or “default”

– Good Security: Pick a hard-to-guess SSID, such as a mix of letters and numbers with no obvious identifying logic.

Get the WLAN Talking• Set the channel

– Most access points run on a single channel– Set the access point channel and all the

clients that associate to it will use the same channel:

– NOTE: 802.11b has 14 channels worldwide and 11 in the United States, but no more than three – 1, 6, and 11 -- that don’t overlap and thus don’t cause interference. This is only a problem if you’re near other WLANs.

Home Networking Tip• “ping”

– Want to find out if your computer is talking to other computers, or the Internet? Send a ping. At a DOS window, type “ping” and the IP address for a computer or a Web site.

Home LAN Issues

WAN settings

• The Wide Area Network (WAN), at least when it concerns your home network, is the network connection from your Internet Service Provider or broadband Cable/DSL company.

• Some ISPs require you to enter information in your router such as:– Static IP address

– Domain Name Server (DNS)

– Point to Point Protocol over Ethernet (PPPoE) for DSL providers, with username and password

Network Address Translation (NAT)

• NAT lets you share the one “real” IP address provided by the ISP among multiple computers on the home LAN.

• The router/gateway gets that IP address from the ISP and translates it for the other computers, working hand-in-hand with DHCP.

Firewall

• Uses rules to filter traffic from the outside Internet to your LAN, and sometimes vice versa. – Built into many routers; also available via

software installed on each computer.

IP Ports

• Not the physical jacks on the back of the PC...• Each port number Identifies the type of data

being sent to/from a computer. – Port 80: HTTP (Hypertext Transfer Protocol, web

browser traffic)– Port 25 & 110: SMTP & POP (Simple Mail Transfer

Protocol & Point Of Presence, e-mail)– Port 21: FTP (File Transfer Protocol)– Port 53: DNS (Domain Name Resolution)

Port Forwarding• Port Forwarding associates traffic meant

for a specific port on the computer and allows it through.

• Setting a computer as a Web server means you forward traffic to port 80 (reserved for Web traffic) on one specific computer, based on its IP address.– Also called port mapping, pass-through,

punch-through– Could require use of a “Dynamic DNS” service

DMZ• The Demilitarized Zone (DMZ) is the term used

for a single computer on the network that is given completely unfettered access to the Internet.

• Traffic can be incoming or outgoing.• Reserve for PCs that are

– Web servers– Gaming systems– Use video conferencing

• That computer is wide open to the Internet and hackers– keep isolated from others.

Universal Plug and Play (UPnP) • UPnP (www.upnp.org) developed by Microsoft,

is meant to automate connection, installation, and configuration of network products

• Performs “NAT Traversal” to automatically open the ports on a PC needed to work with a routers firewall

• Both router and PC must support UPnP to get the benefit– Mainly works under Windows XP for now

VPN Pass-Through

• Virtual Private Networks (VPNs) allow people to create a direct “tunnel” connection to their corporate network. Many routers will allow you to have the tunnel “pass-through” to the Internet and on to the corporate network.

• Watch for how many simultaneous tunnels are supported

Firmware Upgrades

• Firmware is the built-in software inside of a device that defines functions and features

• Updating most access points/routers requires a firmware upgrade.

• Download a software file and generally install via a utility or through the Web browser interface.