Chapter 5 Networks

1. Chapter 5 Networks

2. Learning Objectives After reading this chapter the reader should be able to: • Understand the importance of networks in the field of medicine • Compare and contrast wired and wireless LANs • Describe the newest wireless broadband networks and their significance

3. A network is a group of computers that are linked together in order to share information. • Although a majority of medical data resides in silos, there is a distinct need to share data between offices, hospitals, insurers, health information organizations, etc. • A network can share patient information as well as provide Internet access for multiple users. • Networks can be small, connecting just several computers in a clinician’s office or very large, connecting computers in an entire organization.

4. There are several ways to access the Internet: dial-up modem, WiFi, satellite and broadband access using a Digital Subscription Line (DSL), cable modem or T1 lines. The most common type of DSL is Asymmetric DSL (ADSL) which means that the upload speed is slower than the download speeds, because residential users utilize the download function more than the upload function. Symmetric DSL is also available and features similar upload and download speeds. Cable modem often begins with fiber optic transmission to the building, with coaxial cable run internally.

5. The following are network data transfer speeds based on the different technologies.

6. The Internet Protocol (IP) is a standard that segments data, voice and video into packets with unique destination addresses. Routers read the address of the packet and forward it towards its destination. Transmission performance is affected by the following:

7. Factors affecting transmission performance • Bandwidth: is the size of the pipe to transmit packets. In reality, networks should have bandwidth excess to operate optimally • Packet loss: packets may rarely fail to reach their destination. The IP Transmission Control Protocol (TCP) makes sure a packet reaches its destination or re-sends it. The User Datagram Protocol (UDP) does not guarantee delivery and is used with, for example, live streaming video. In this case the user would not want the transmission held up for one packet • End-to-end delay: is the latency or delay in receiving a packet. With fiber optics the latency is minimal because the transmission occurs at the speed of light • Jitter: is the random variation in packet delay and reflects Internet spikes in activity

8. Network Types Networks are named based on connection method, as well as configuration or size. As an example, a network can be connected by fiber optic cable, Ethernet or wireless. Networks can also be described by different configurations or topologies. They can be connected to a common backbone or bus, in a star configuration using a central hub or a ring configuration. In this chapter we will describe networks by size or scale.

9. Personal Area Networks (PANs) • Local Area Networks (LANs): • Wired networks: To connect to the Internet through your Internet Service Provider (ISP) you have several options. Modem: you can use the older and slower modem technology to connect your computer to the Internet over routine phone lines. Ethernet is a network protocol and most networks are connected by fiber or twisted-pair/copper wire connections. Ethernet networks are faster, less expensive and more secure than wireless networks.

10. Wireless (WiFi) networks (WLANs): Wireless networks have become much cheaper and easier to install so many offices and hospitals have opted to go wireless to allow laptop/tablet PCs and smartphones in exam and patient rooms. In general, wireless is slower than cable and is more expensive, but does not require hubs or switches.

11. 3. Wide Area Networks (WANs): Cross city, state or national borders. The Internet could be considered a WAN and is often used to connect LANs together. 4. Global Area Networks (GANs): The problem with broadband technology is that it is expensive and the problem with WiFi is that it may result in spotty coverage. These shortcomings have created a new initiative known as Worldwide Interoperability for Microwave Access (WiMax), using the IEEE 802.16 standard. The network will be known as a global area network (GAN).

12. 5. Virtual Private Networks (VPNs): If a clinician desires access from home to his/her electronic health record, one option is a VPN. In this case your home computer is the client and the computer at work you are trying to access is the VPN server. The Internet is the means of connection and VPN will work with wired or wireless LANs. Authentication and overall security are key elements of setting up remote access to someone else’s computer network.

13. Key Points • Clinicians who use client-server based electronic health records need to establish a wired or wireless office network • Wireless networks have become more attractive due to faster speeds and lower prices • Wireless broadband is around the corner and will make Internet access faster and more widely available

14. Conclusion Hospitals’ and clinicians’ offices rely on a variety of networks to connect hardware, share data/images and access the Internet. In spite of initial cost, most elements of the various networks discussed continue to improve in terms of speed and cost. Many clinician offices will require a network expert to ensure proper installation and maintenance. Wireless technology (WiFi) has become commonplace in many medical offices and hospitals. When wireless broadband (WiMax- LTE) becomes cost effective and widely available it may become the network mode of choice. Network security will continue to be an important issue regardless of mode.