Network Infrastructure

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While you are documenting your current network environment, take special note of areas where you are currently experiencing problems. If you stabilize your network before deploying a new operating system, deployment and troubleshooting will be easier, and you can have increased confidence in the upgraded network. Setting up a test lab to duplicate problems and configurations is a good way to evaluate the impact of deploying Windows 2000 with a given set of protocols, hardware drivers, and client/server configurations. For more information about setting up a test lab, see "Building a Windows 2000 Test Lab" in this book.

When documenting your network infrastructure, you are obtaining both hardware data to document your infrastructure's physical structure and software data to document the existence and configuration of the protocols in use on your network. You also need to document the logical organization of your network, name and address resolution methods, and the existence and configuration of services used. Documenting the location of your network sites and the available bandwidth between them will also assist you in deciding whether to perform push or on-demand installations when you upgrade or migrate to Windows 2000. For more information about installing, upgrading, and migrating to the Windows 2000 operating system, see "Automating Client Installation and Upgrade" and "Automating Server Installation and Upgrade" in this book.

Developing a physical and logical diagram of your network will help you organize the information you gather in an understandable and intuitive manner.

Physical Network Diagram

The physical diagram presents the following information about your existing network:

  • Details of physical communication links, such as cable length, grade, and approximation of the physical paths of the wiring, analog, and ISDN lines.

  • Servers, with computer name, IP address (if static), server role, and domain membership. A server can operate in many roles, including primary or backup domain controller, Dynamic Host Configuration Protocol (DHCP) service server, Domain Name System (DNS) server, Windows Internet Name Service (WINS) server, print server, router, and application or file server.

  • Location of devices such as printers, hubs, switches, modems, routers and bridges, and proxy servers that are on the network.

  • Wide area network (WAN) communication links (analog and ISDN) and the available bandwidth between sites. This could be an approximation or the actual measured capacity.

  • Number of users at each site, including mobile users.

Figure 6.1 is an example of a physical network diagram.

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Figure 6.1 Physical Network Diagram

Document firmware version, throughput, and any special configuration requirements for any devices on the network. If you assign static IP addresses to any of these devices, record them. For more information about network connectivity and Windows 2000, see "Determining Network Connectivity Strategies" in this book.

Logical Network Diagram

The logical diagram shows the network architecture, including the following information:

  • Domain architecture, including the existing domain hierarchy, names, and addressing scheme.

  • Server roles, including primary or backup domain controllers, DHCP service servers, or WINS servers.

  • Trust relationships, including representations of transitive, one-way, and two-way trust relationships.

Figure 6.2 is an example of a logical network diagram.

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Figure 6.2 Logical Network Diagram

Network Configuration

In general, the areas of your network configuration that you need to document are listed in the following sections.

Name Resolution Services

Ensure that you have documented all DNS and WINS servers that are on your network, noting configuration and version information as well as hardware details. Note whether any of the DNS servers not running Windows NT on your network can support dynamic registration and Service (SRV) resource records, and whether upgrades for this capability are available from the software manufacturer.

If you have hosts on your network that are not running Windows NT, document the services they use and provide, such as UNIX BIND. You should also document the version of each service in use. For example, if BIND is used on your network, note that versions earlier than 4.9.4 are not compatible with Windows 2000. Document Service Advertising Protocol (SAP) and Routing Information Protocol (RIP) services, if either are presently in use on your network.

IP Addressing Methods and Service Configurations

Ensure that you have documented all DHCP service servers on your network, including the following:

  • Any IP addresses that you have assigned servers or client computers.

  • DHCP settings, such as the default gateway.

  • Details of your subnets, and relate them to your overall domain structure.

  • The number of subnets and hosts on your network, and record the IP addresses and submasks used on your network.

  • How long a client can lease an IP address on your network.

Remote and Dial-up Networking

If you have remote or mobile users, document your remote access and dial-up configurations. If you use third-party software for mobile users, review and document the configuration of those products. If you use virtual private networks (VPNs), document the configuration of your VPN with the goal of evaluating whether you can replace it with Windows 2000 VPN.

Bandwidth Issues

Document your network's current bandwidth utilization. Do this to establish a baseline from which changes can be measured. You can use a variety of third-party and Microsoft tools to measure bandwidth metrics such as bytes and packets sent or received, transmit and receive errors, and packets per second. Document the speed of the network links between your organization's network segments and geographical locations.

Look at the logical and geographical dispersion of your organization in terms of bandwidth considerations. Does it have branch offices, or mobile or remote employees? Consider the amount and type of traffic over your organization's communication links. For instance, are your WAN links periodically slowed by domain replication between domain controllers at different sites? Document the net available bandwidth of all WAN links and network segments. Try to record available bandwidth during the course of low, normal, and high network utilization.