LAWN System Diagram

Below are diagrams of the LAWN network, including an overview of how the network is put together and a description of how clients connect and authenticate.

a. Wireless Clients

The wireless radio in your device (laptop, pda, phone, etc.) looks for the LAWN SSID (GTwireless) by using the required valid WEP Key. If a LAWN access point is within range, your device will associate with the access point; connecting your device to the LAWN network. If you want to know more, go to our 802.11 wireless protocol page.

b. Walkup Port Clients

Your device (laptop, pda, phone, etc. is plugged into a walkup port with and ethernet cable (cat5/category5);connecting your device to the LAWN network.

The TCP/IP settings for your device will need to be set to use DHCP. When your device is connected to the LAWN, the Dynamic Host Configuration Protocol (DHCP) will find and lease an available IP address for you to use on the LAWN. It does this by requesting an address, and receiving an acknowledgement from the Mower (the LAWN server and gateway). Leases are given for 10 minutes at a time. If you are actively using your device, it will renew the lease indefinitely by repeating the request and acknowledgement exchange every ten minutes. If your device is not in use and goes into "sleep mode", or is otherwise disconnected from the network, the lease will not be renewed and you will lose your lease on this IP address. To get back on the LAWN, you will have to "wake up" or reconnect your device so that it will look for a new IP address.

Leasing an IP address allows you to communicate with other devices on the LAWN, but it does not allow you to communicate with the Gerogia Tech network or to external networks. You must authenticate, or log in, to the LAWN in order to do much of anything such; as reading mail, instant messaging (IM), or browsing the web.

Curently we use a method of authentication called captive portal. When you use a web browser to connect to any web site, say google.com, your device sendsan http:// request through the mower. (First your device will do a Domain Name Server (DNS) lookup find the IP address associated with the site, this is allowed to pass through the mower without authentication.)

If you are not logged in, the mower will not allow communication with the site (X), but rather redirect (automatically using javascript or manually by presenting a link for you to click) you to an SSL authentication page on the Mower. This process of circumventing the initial request to go to google.com and making you login is called Captive Portal.

When you receive the authenication or login page, you will need to type in your GT account username and password. When you press the Login button, it posts this to the mower. If the username and password are correct, the mower will respond by displaying that you are logged in successfully. This message appears briefly and then redirects (automatically using javascript or manually by presenting a link for you to click) you to your original destination site. Further requests to this site or any other will be allowed to pass without authenticating, provided your host stays connected and continues to renew your
DHCP lease.