Windows Small Business Server 2011 : Planning the Network Infrastructure (part 1)

7/12/2011 4:41:24 PM

The first tasks in designing a network for your company are

Evaluating the computing needs of the organization
Choosing an Internet connection method and local network type
Selecting network devices
Choosing server hardware
Choosing client hardware and software

UNDER THE HOOD: Network Operating Systems

On an ordinary PC, the role of the operating system is to manage the file system; handle the running of applications; manage the computer’s memory; and control the input and output to attached devices such as cameras, printers, and scanners. A network operating system expands that role, managing the following:

Centralized security
Remote access
Remote file systems
Running shared applications
Input and output to shared network devices
CPU scheduling of networked processes

When multiple computers are connected in a workgroup, as shown in Figure 1 , the result is called a peer-to-peer network: a network without a central server and with no network operating system.

Figure 1. A peer-to-peer network, which has no central server or management

Adding one or more servers running Windows Server 2008 R2 or a Windows Small Business Server 2011 Standard, as shown in Figure 2, is a client/server-based network—one or more servers and multiple clients, all sharing a single security policy. The servers provide both the resources and the security policy for the network, and the clients are the computers that use the resources managed by the server.

Figure 2. A client/server network, which has a central management and resource server

Servers Use Network Operating Systems

Because SBS 2011 has to supply services to as many as 75 users, and you’re depending on it to run your business, a high-powered, robust operating system and highly reliable hardware are essential. When your users rely on a server to get their work done and keep your business running, you certainly don’t want frequent failures—you don’t even want to reboot!

In addition to supplying print, file, or other services, the network operating system has to provide network security. Different businesses and organizations have varying security needs, but all must have some level of data protection. Therefore, the system must offer a range of configurable security levels, from the relatively nonintrusive to the very stringent.

Clients Use Workstation Operating Systems

Like other computers, client computers on a network need an operating system. However, a client operating system doesn’t need to manage the resources for other computers or manage security for the network. Rebooting a workstation can be an annoyance for the user but doesn’t usually disrupt anyone else’s work.

On a Windows Small Business Server network, clients can run Microsoft Windows XP Professional (including Windows XP Tablet PC Edition and Windows XP Professional x64 Edition) and business editions of Windows Vista or Windows 7. However, for best performance and security, Windows Vista SP1 or Windows 7 should be deployed on clients.

1. Determining Your Needs

Before designing a network, decide which features of SBS 2011 your business needs; doing so helps ensure that the network design is dictated by business needs rather than by fancy technology. Key needs to consider include

Centralized user account management
Centralized update management
Web and email access for employees
File sharing and centralized file storage
Database storage using Microsoft SQL Server
Printer sharing
Centralized backup
Centralized fax server
Remote access to the internal network via the Internet, including remote access directly to the user’s desktop from the web
Management of remote computers
Collaboration and document management (SharePoint Foundation 2010)

You also must decide how important the following factors are, as well as what resources are available to support your choices:

Performance
Reliability
Security

Note:

PLANNING Get a thorough idea of what kind of work will be done on the network, when and where it will be done, and by whom. For example, your organization might need to do payroll every other Friday, during which time the file server and printers are under a heavy load.

2. Choosing an Internet Connection

To choose an Internet connection method, you must balance an organization’s bandwidth needs and budget against the available Internet connection methods. The following sections discuss how to do this, as well as how to choose an Internet service provider (ISP).

2.1. Determining Bandwidth Needs

First, determine the baseline level of bandwidth you require. You can then balance this against the organization’s budget and performance goals. Allow for 100 kilobits per second (Kbps) of download bandwidth and 50 Kbps of upload bandwidth for each simultaneous user of email and the web. If remote access is important, allow for a minimum of 100 Kbps of upload bandwidth for each simultaneous remote access user. Table 1 lists various Internet connection speeds and the number of users supported for each speed, assuming that users will be browsing the web and using email. This table does not include requirements for remote connections.

Warning:

IMPORTANT Running an Internet-accessible web server on your network requires at least 50 Kbps or more of upload bandwidth per simultaneous visitor, depending on the size of images or files. This can quickly swamp your Internet connection, which is one reason most small businesses pay for web hosting.

Table 1. Bandwidth requirements for web browsing and email
DOWNLOAD/UPLOAD SPEED	NUMBER OF USERS
256/128 Kbps	1–5
512/256 Kbps	1–5
1024/512 Kbps	5–10
3072/768 Kbps	10–20
5120/1024 Kbps	15–30

Note:

These bandwidth numbers are not intended to be definitive—they are a minimum planning baseline. Each organization and its users have different usage patterns and needs, and you should evaluate your needs accordingly. Be prepared to add more bandwidth if necessary. Your users will never complain that the Internet connection is too fast, but they will definitely complain if it’s too slow!

UNDER THE HOOD: Bits and Bytes

Network speeds are measured in either kilobits per second (Kbps) or megabits per second (Mbps), whereas download speed and hard disks are rated in kilobytes per second (KBps) or megabytes per second (MBps). For example, a 640-Kbps DSL connection might download files at 60 KBps from a fast website, but a 1.5-Mbps cable Internet connection might download at 180 KBps from the same site. (Some of the bandwidth is used up by transmission overhead and inefficiencies.) When you compare network speeds, make sure you’re using the same units of measurement.

2.2. Types of Internet Connections

To choose an Internet connection method, you need to know which methods are available as well as their performance characteristics. Table 2 lists the most common connection methods and their speeds.

Table 2. Internet connection types
TYPE OF CONNECTION	DOWNLOAD SPEED	UPLOAD SPEED	NOTES
Dial-up	28.8–53 Kbps	28.8–40 Kbps	Analog telephone line. Sometimes referred to as Plain Old Telephone Service (POTS).
ISDN (Integrated Services Digital Network)	64–128 Kbps (one channel or two)	64–128 Kbps (one channel or two)	Must be within 50,000 feet of a telephone company central office (CO). Connection is dial-up (not persistent).
ADSL (Asynchronous Digital Subscriber Line)	256 Kbps–8 Mbps	128 Kbps–1 Mbps	Must be within 18,000 feet of a CO.
IDSL (DSL over ISDN)	128–144 Kbps	128–144 Kbps	Works at greater distances from a CO than other DSL variants.
SDSL (Synchronous DSL)	128 Kbps–2.3 Mbps	128 Kbps–2.3 Mbps	Must be within 20,000 feet of a CO.
Cable	128 Kbps–15 Mbps	128 Kbps–1 Mbps	Must have access to broadband cable service; speed can fluctuate depending on the number of users on a given cable loop.
Microwave wireless	256 Kbps–10+ Mbps	256 Kbps–10+ Mbps	Must be in line of sight to the ISP’s antenna; maximum distance 10 miles.
Frame relay/T1	56 Kbps–1.54 Mbps	56 Kbps–1.54 Mbps	Good availability; very reliable; consistent throughput; expensive.
802.11b (WiFi)	Up to 11 Mbps	Up to 11 Mbps	Speed decreases with increasing distance from access point.
802.11g or 802.11a	Up to 54 Mbps	Up to 54 Mbps	Speed decreases with increasing distance from access point.
802.11n	Up to 540 Mbps	Up to 540 Mbps	Speed decreases with increasing distance from access point.
Geosynchronous satellite	150 Kbps–3 Mbps	33.6 Kbps–128 Kbps	Requires line of sight to satellite (southern sky in North America). Unsuitable for real-time multimedia because of high latency.
Ethernet	10 to 1000 Mbps	10 to 1000 Mbps	Limited availability. Backbone connection might be DSL or T1, limiting actual bandwidth.

2.3. Choosing ISPs

After determining the preferred connection type and bandwidth, it’s time to actually find ISPs. Two websites to check are http://www.cnet.com/internet-access and http://www.dslreports.com . In addition to speed and cost, look for the following features:

Static IP address To host any kind of Internet-accessible service such as email, Microsoft Outlook Anywhere, remote access, or websites, you need a static IP address or an ISP that supports the Dynamic DNS service, or you need to manage your external DNS with a DNS service that supports dynamic updates, such as http://www.zoneedit.com . SBS 2011 includes support for tzo.com dynamic DNS if you use the built-in wizards to register or transfer your domain name.
Terms of service and ports Many ISPs have terms of service (TOS) on consumer-grade accounts that prohibit hosting email servers, or they have a policy that blocks specific ports such as port 25. You need to ask before you buy.
Transfer limitations If the ISP has a monthly data transfer limit, make sure the limit isn’t lower than your anticipated usage—charges for going beyond the limit can be significant.
Web hosting If you want the ISP to host the organization’s Internet website, look for virtual hosting (so that your organization can use its own domain name) with enough disk space on the ISP’s web servers.
Backup Internet connection If your business is dependent on always being connected to the Internet, choose a secondary Internet connection with sufficient bandwidth to allow you to maintain minimal service in case the primary Internet connection fails. This second Internet connection should use a different ISP and a different connection technology. You can use a dual WAN router to use both connections simultaneously.