Local area networks
A local area network can be badly damaged by flooding. Network cabling can become waterlogged and non-functional. Patch panels and jacks can be water damaged as well. The switches, hubs, routers, and other electronic devices on your network may well be knocked out by the water. Fully restoring a complicated network can take time and effort, but it’s possible to build out an ad hoc local area network quickly.
To build a simple network, start with an Ethernet hub or switch. Ethernet and TCP/IP networking technologies are the most common networking technologies in use, and are relatively robust and easy to setup in an ad hoc fashion. The hub or switch forms the backbone of your network and manages network traffic between the different computers and devices on your network. To create an ad hoc network, just about any hub or switch will do. If you need to add capacity, most devices include a crossover switch or port, which can be used to connect two devices together using a basic network cable. Some newer devices include auto-sensing ports that automatically adjust for connecting two switches or hubs together.
Once you have a working hub or switch in place, you can start connecting computers to the network using standard Ethernet cables. Try to run the cables along the base of walls and out of the way of foot traffic. Ethernet cables are easy to trip over, and when yanked, can break connectors and jacks, pull equipment to the floor, and otherwise cause havoc. If you need to run cable across a traffic path, try taping the cables to the floor to keep them out of the way. (Note, when pulling up taped down cables, try pulling the tape off the cable while it is still on the floor. Pulling up the tape and cable together is likely to result in tape wrapping around the cable, which becomes very difficult to remove.)
Most computers include Ethernet network interface cards with RJ-45 jacks (they look like large telephone connection jacks) for connecting them to networks. If your computers do not have network cards, they are relatively inexpensive and can be easily installed in any PC.
Another option for an ad hoc network is the use of wireless technologies. The 802.11b and 802.11g standards, often referred to as “Wi-Fi� are easy-to-use and well-supported. The older and slower 802.11b standard is less secure, but also somewhat cheaper than the newer, faster, and more secure 802.11g standard. In any event, either technology is acceptable for an ad hoc network.
Wireless networks consist of access points, which are often built into cable and DSL routers, and wireless network cards, which allow computers to connect to the access point. Access points, much like wired switches and hubs, have limited capacity. For large installations, more than one access point may be required. Wireless networks, due to their “broadcast� nature, require the use of basic security precautions. There are two common WiFi security technologies. WEP, which is associated with 802.11b networks, and WPA, which is associated with 802.11g networks. WEP is no longer considered very secure, but is adequate for an ad hoc network. WPA is much more secure, and is appropriate for both ad hoc and permanent networks.
Once the computers and devices are plugged in to the network, or set up on the wireless network, they may need to be configured. Many TCP/IP networks use DHCP to automatically assign addresses and other information to network devices. Most routers and servers include DHCP servers. You may find that your computers automatically configure themselves properly when plugged into the network.
If your network does not have an active DHCP server, you may need to manually configure the network settings on your computers and devices. For Windows, this is done through Networking or Network Connections control panel. For Macintosh 8.x to 9.x, this is done through the TCP/IP control panel. For Macintosh OS X, this is done through the Network system preferences pane.
For an ad hoc network, you want to set all the computers up on the same subnet. This means providing each computer or device with its own unique address. We recommend using a non-routable address range, such as 192.168.100.X. X can be any number between 1 and 254. Every computer or device should share the first three sets of numbers, and then have a different set of final numbers. Each computer should share the same subnet mask, which should be 255.255.255.0. If there is a functioning Internet router on the network, add its IP address as the default gateway.
It’s possible to share a network with other organizations in a somewhat secure fashion. Ideally, we recommend using a router to segment off the different parts of a network.
Internet Access
Many organizations have become increasingly reliant on the Internet to communicate, conduct research, and interact with other organizations. There are many options for restoring Internet connectivity, and which one is appropriate for your situation depends on what services are available to you and what equipment you have access to. The following is a list of scenarios for obtaining Internet connectivity for temporary offices while providing services in an area affected by a disaster.
- Solution A High-speed connection on site. If the host site for the organization has Internet access via T1, DSL, or cable, the connection could be borrowed via a wireless access point or a long Ethernet cable, even if the service center is not in a room with Internet access.
Pro: Fast, potentially no monetary cost.
Con: Few shelters/service center sites may have high-speed Internet access. Equipment required: SOHO router, cabling ~$150. - Solution B Wi-Fi bridge. Depending on the location, there may be a Wi-Fi access point near the service site. With the right equipment, the signal can be brought onto a wire and redistributed to one or more computers. In some circumstances there would be no cost for the connection. In other cases, there would be a charge for connecting (to a T-Mobile hot spot at Starbucks, for example). This might require an antenna mast or temporary mounting of an antenna on the roof of the building.
Pro: Potentially fast, possibly no per-minute charges.
Con: Somewhat complicated to set up. Equipment required: Wi-Fi/Ethernet bridge, antenna, cabling, router/access point ~$600. - Solution C Dial-up. An individual computer could dial in to an ISP over a telephone line. Several computers could be serviced via a wired or wireless LAN by means of a router with a modem built in, or a computer with a modem and Internet Connection Sharing turned on.
Pro: works anywhere there is an available phone line.
Con: Connection slow, monthly cost to maintain account. Equipment: none for individual computers, for dialup LAN ~$400. - Solution D Mobile Phone/Data card. Individual computers can access the Internet using either PC cards or mobile phones attached by a cable. Such an Internet service connection could be shared on a network by a computer with Internet Connection Sharing.
Pro: Works anywhere there is cellular service, faster than dial-up.
Con: Per-minute charges could be pricey. Equipment: $200 - $300 per laptop. - Solution E
Satellite Internet service. Dish captures a broadcast a signal; can be shared with clients over wired or wireless LAN.Pro: Works almost anywhere. Somewhat faster than dial-up.
Con: Expensive, not particularly easy to set up. Equipment: Also expensive. Satellite equipment, possibly LAN equipment runs ~$400.
Sharing a network
Sharing a network or Internet connection with multiple organizations may be the only available solution. This is relatively simple, but requires some planning so that each organization can get the resources that it needs. Start by setting up the core network where the Internet connection, if any, comes into the office. Most consumer and small business networking equipment can theoretically support around 250 separate computers or network devices, though the more heavily used the network, the fewer devices a router will be able to handle before failing.
Organizations with concerns around privacy and confidentiality may want to use a second router to segregate off their sections of the network. It’s possible to use multiple routers to create a number of different sub-networks that all tie into the core network.
For organizations that have less stringent security needs, sharing a single network should not present many difficulties. The key to smoothly sharing a network is to set up each organization's computers with a different workgroup name and provide each computer with a descriptive name. In Windows, you can set up computer and workgroup names using the Computer Name tab in the Control Panel. For Macintosh OS 8.x – 9.x computers, you can set the computer name in File Sharing control panel. For Macintosh OS X computers, you can set the computer name in the Sharing System Preference pane. Macintosh computers do not natively use workgroup names.