A Basic Network Wiring Trace
To illustrate the overall layout of a basic Cat5 network in a small office, Figure 2 provides a simplistic look at the physical path of a data packet traveling through a LAN. Let's walk through it step by step, so that you can clearly understand the layout.
- From a PC in a work area, the packet travels out of the NIC through a patch cable to the RJ-45 jack in a wall plate.
- From the wall plate, the packet travels over the wall plate–connected cable (i.e., horizontal wiring) to a telecommunications closet that terminates at a jack in a patch panel.
- The packet then goes through a patch cable that cross-connects the horizontal wiring to the backbone wiring.
- The packet then heads to the equipment room, where it connects to another patch panel.
- A final patch cable connects the equipment room's patch panel to a network switch.
- The switch then sends the packet to its destination, which could be a server on the LAN or a router interface to another LAN or the Internet.
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Return traffic back to the initial PC would traverse the same equipment in reverse order.
Network Clients
Because the typical purpose of a network is to allow a client system to communicate with other systems, let's discuss the requirements of a networked client. Assuming the client's OS supports networking via a supported protocol (which is almost always TCP/IP), all that's necessary is a NIC and a path to another system. The simplest computer network consists of two systems, each with a NIC, and with a specially wired crossover cable between them. Although most business-class systems feature an integrated NIC, you should know that multiple varieties of NICs exist. Offerings from 3Com and Intel—by far the most popular—are good choices. Don't settle for a NIC that has less than full-duplex 100Mbps capabilities, which shouldn't be a problem; tier-one suppliers are including 1000Mbps (Gigabit) NICs onboard their systems.
Hubs and Switches
Although you can use minimal equipment to configure a two-system network, configuring three or more systems requires at least one additional piece of hardware: a switch or a hub. Switches and hubs both permit multisystem communication on a network, but for a few good reasons, switches are by far the favored choice of today's businesses. In simple terms, whereas a hub provides a shared connection to the network for all connected devices, a switch establishes a dedicated communication path for network conversations between two devices on the network. This functionality greatly reduces the chance of collisions (multiple conversations on the same network media conflicting with one another) and thus increases throughput. Also, devices connected to a hub share all the hub's available bandwidth, but devices connected to a switch receive a predefined allotment of bandwidth. Switches also offer improved security by preventing a host from seeing traffic not directed to it.
An excellent choice for SMBs today, 100Mbps switches are quite affordable. Those businesses that have a higher demand for bandwidth might need to implement 1Gbps switches.
Routers
It doesn't make sense for network traffic destined for your LAN to travel across expensive WAN or backbone connections. A router's job is to contain local network traffic while ensuring that traffic destined for another segment has a path, or route, to get there. An ideal location for a router is between your corporate network and the Internet. One of the first vendor names to come to mind when you think of routers is Cisco, but in the SMB space you have many fine choices that will provide what you need without breaking your budget. Cisco recognizes the need for some middle ground and targets its Linksys brand to SMBs.
Other SMB Networking Considerations
SMBs can no longer hide from the wireless-network push. As soon as an executive asks to use a wireless-enabled laptop in a meeting room, the proverbial genie is out of the bottle. To protect your network and effect a smooth transition to wireless, you can adhere to Wi-Fi standards such as 802.11g and purchase proven solutions by name-brand vendors. Watch for a later article in this series to walk you through the implementation of a wireless network. In the meantime, consider how a wireless network might help you build your network infrastructure in areas where physical wiring is prohibitively expensive or impossible to install.
Also, if you plan to connect your company's network to the Internet, you must take precautions to protect your internal resources from intrusion and attacks. Connecting your company's network to the Internet without a firewall is like leaving the doors to your headquarters unlocked 24 × 7. Just one unscrupulous visitor can wreak havoc on your company's assets. Firewalls inspect the network traffic between security zones and decide whether to permit or deny that traffic. Generally speaking, this inspection occurs at either the network layer or the application layer of the protocol stack. Network-layer inspection is considered faster than application-layer inspection, but it doesn't provide as detailed an inspection of the packets. This lack of a thorough inspection might make packets more susceptible to breach.
Whether you build your entire network internally or use outside resources, employing proven design and implementation techniques will ensure a solid foundation for your data movement in your company. Additionally, having the knowledge and documentation for how your network is put together will save many hours of troubleshooting when a problem does arise.
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