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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2
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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.