Module 9: Installing and Configuring Network Load Balancing

Module 9: Installing and Configuring Network Load Balancing

Overview Pre-Installation Network Load Balancing Driver Installation
Configuring the Network Load Balancing Driver Cluster Parameters Host Parameters Port Rules TCP/IP Properties Post-Installation Configuration

In this module, you will install and configure the Network Load Balancing driver. You will learn how to configure the driver by selecting the appropriate settings for the Network Load Balancing and TCP/IP Properties dialog boxes. Before you install the Network Load Balancing driver, you will complete a pre-installation checklist that will determine if your network capacity and configuration can meet your needs, you have configured the hosts correctly, and the addressing architecture is appropriate for the cluster. This module will also address issues with post-installation configuration, including how to avoid flooding switch ports and how to adjust convergence parameters.

After completing this module, you will be able to:
Describe the pre-installation decisions for a clustering solution. Install the Network Load Balancing driver. Configure the Network Load Balancing driver. Select the appropriate settings on the Cluster Parameters tab. Select the appropriate settings on the Host Parameters tab. Select the appropriate port rules for the cluster. Determine the proper setting for the Transmission Control Protocol/Internet Protocol (TCP/IP) stack. Determine the post-installation configuration for the cluster.

Pre-Installation Verify that TCP/IP is bound to the network card
Verify that aggregate subnet throughput supports IP traffic Verify that the throughput of each host is documented Verify that cluster members support client throughput Verify that all IP addresses are manually allocated Verify that TCP/IP is bound to the network card

In designing a Network Load Balancing solution, you will collect all of the relevant information that is required to configure your cluster, but initially there are some common considerations that you must address for all of the cluster solutions. Prior to installing the first cluster host, complete the following tasks:

Ensure that only TCP/IP is bound to the network card that you will use as the cluster adapter. The Network Load Balancing driver intercepts and supports all IP packets that the hardware driver of the cluster adapter forwards. The Network Load Balancing driver only supports IP packets. If other protocols, such as Internetwork Packet Exchange (IPX), must be supported, verify that you have installed multiple network interface cards (NIC) in the computer.

Ensure that the aggregate throughput of the subnet will support both cluster IP and dedicated IP traffic for the required number of hosts. If the subnet utilization is a concern, you can install multiple network cards or use round robin DNS entries to allow for a reduction in the number of hosts per cluster.

Ensure that you have documented the throughput of each host
Ensure that you have documented the throughput of each host. If you have configured all of the cluster members identically, the throughput will be similar. For example, if all of your hosts have the same number of CPUs, clock speed, and network cards, their throughput rate will be very similar. If your computers have different clock speeds or number of CPUs, then the throughput rate of each will vary. If you use computers with different throughput rates, you can use the manual load balance feature of Network Load Balancing to distribute clients across cluster members.

If you are going to use Network Load Balancing in a failover mode of operation, ensure that all of the members of the cluster can support the required client throughput. You may deliberately design your system to have performance degrade during failover; for example, if your default host is a quad CPU computer, you can assign a dual CPU computer with lesser throughput as the next priority (failover) computer, accepting that the performance will degrade until the original default computer is repaired and brought back online.

Ensure that all of the IP addresses that you will use for the Network Load Balancing cluster are manually allocated. The Network Load Balancing driver is not a Dynamic Host Configuration Protocol (DHCP) client and cannot use DHCP-allocated addresses. If the address range that you use is within a corporate DHCP group, ensure that the Cluster IP addresses are excluded from any defined ranges.

Hardware Considerations
No special hardware requirements Ethernet or FDDI All hosts on one broadcast subnet All host on one Level 2 switch or VLAN All hosts on a single hub or repeater Two NICs per host preferred: One NIC for cluster traffic and heartbeats One NIC for replications/backend access

The Network Load Balancing driver runs within the cluster hosts as part of the Microsoft® Windows® 2000 Advanced Server operating system; it does not require dedicated hardware support. The current version of the Network Load Balancing driver operates on Fiber Distributed Data Interface (FDDI) or Ethernet-based local area networks (LAN) within the cluster. All cluster members should be on the same broadcast subnet, in the same virtual LAN, or on a single hub. While the Network Load Balancing driver will work successfully by using one NIC, two NICs are preferred. Using two NICs will enable the cluster IP and heartbeat traffic to operate on one NIC and IP traffic for an individual host to operate on the second NIC; for example, when you use two NICs, traffic associated with replication services and backend access to a database is separated from the cluster inbound traffic.

If your Network Load Balancing solution will include multiple NICs, it is recommended that the cluster IP and dedicated IP be on different subnets to maximize the throughput available to cluster IP traffic. Using different subnets increases security by providing isolation between public and private traffic. If all of the NICs are connected to the same subnet, it can create throughput and security limitations in the network. The network adapters that you use must support dynamic allocation of the media access control (MAC) address and multicast MAC address requirements. Both multicast and unicast modes of operation will result in the Network Load Balancing driver programming new MAC addresses into the card.

Controlling Switch Flooding
Hosts on individual ports results in switch flooding Hosts on a hub limits switch flooding Cluster host Non-Cluster host Layer 2 switch Layer 1 hub Hub

In many networks where collapsed backbone switching technology is used, there are very large port counts available. Typically in these environments individual computers are allocated a single switch port to provide maximum possible bandwidth to the computer. If the cluster hosts are directly connected to a switching hub or combined switch/router to receive client requests, you must send incoming client traffic to all of the switch ports that are supporting cluster hosts. After a switching hub has identified which port a particular host (recognized by its MAC address) is connected to, it will no longer duplicate inbound traffic to all of the ports.

Network Load Balancing service prevents a switching hub from identifying the host’s port by masking the source MAC address by using a different MAC address in reply. Masking the source MAC address results in the switch continuing to send inbound data to all of the ports, which is called switch flooding. If the switch has ports associated with computers other than cluster hosts, these ports will also have the inbound traffic reflected on them, consuming bandwidth on ports where the traffic will be discarded.

Considerations for Switch Flooding
Switch flooding can become a problem when:

Applications have significant inbound network traffic directed to the cluster IP; for example where large file uploads use File Transfer Protocol (FTP), the cluster IP will accept a large amount of inbound network traffic. Multiple clusters share a switch and their combined inbound traffic becomes significant compared to the switch port capacity. A switch is configured to use ports to connect to a backbone network that has a higher speed than those that are used to connect to cluster hosts. Under this circumstance, switch occupancy can become high, reducing available bandwidth on all of the ports. For example, consider a multiple cluster solution, where a switch uses a gigabit port to connect to a backbone and 100 megabits per second (Mbps) ports for the individual cluster hosts, with a total inbound traffic average of 20 Mbps. Because all of the traffic will be reflected to all of the ports, the switch occupancy will average 20 percent for all of the cluster hosts. One solution to this scenario is to use multicast mode and set up a virtual LAN in the switch to limit switch flooding.

Switch Flooding Solutions
You can avoid switch flooding problems by using two network adapters per host on the cluster subnet to direct network traffic through the cluster hosts by separating inbound and outbound data. Using two network adapters allows incoming client traffic to flow through the switching hub for simultaneous delivery to all of the hosts, while outgoing traffic flows directly to the switch ports. If you assign a gateway and interface metric for the dedicated adapter that is less than the value assigned to the cluster adapter, the dedicated adapter will be used for outbound traffic.

You can limit all of the traffic for a cluster to one switch port, thereby conserving switch bandwidth. Connect the individual cluster members to a hub, with the hub connected to a single switch port. This solution is viable providing that a single port will support the maximum required throughput for the cluster. Important: Where all of the cluster members are connected to a single switch port the switch can be allowed to learn the MAC address by setting the registry setting for HKEY_LOCAL_MACHINE\SYSTEM\ CurrentControlSet\Services\WLBS\ Parameters\MaskSourceMAC = 0 on all Network Load Balancing hosts. Changing the registry setting allows the switch to direct inbound traffic to only one switch port, eliminating switch flooding.

Network Load Balancing Driver Installation
NLB Cluster Host 1 Properties General Connect using: Configure Description Sharing Intel® PRO/100+ Management Adapter Components checked are used by this connection: Client for Microsoft Networks Network Load Balancing Network Monitor Driver Internet Protocol (TCP/IP) Install… Uninstall Properties This component provides TCP/IP load balancing functionality. Show icon in taskbar when connected Cancel Close Select Driver Configure – Cluster Parameters Host Parameters Port Rules Exit Dialog Box

The Windows Network Load Balancing driver is associated with a single network adapter in your computer. Configuring the properties of the network adapter that will perform Network Load Balancing completes installation of the driver. To avoid networking problems, follow these steps in the exact order shown.

To install Network Load Balancing:
Open Network and Dial-up Connections. Right-click the Local Area Connection on which you will install Network Load Balancing, and then click Properties. The Local Area Connection Properties dialog box appears. Under Components checked are used by this connection, you see Network Load Balancing. Note that it is listed but not selected. (If Network Load Balancing is not listed, search for Installing Network Load Balancing If It was Previously Uninstalled in the Help for Windows 2000 Advanced Server.) Select the Network Load Balancing check box, which will enable the driver. Click Properties to continue configuring the driver or click Close to exit the Local Area Connection Properties dialog box.

Important: If this is the first time that the driver has been enabled, it requires further configuration; if the driver was previously configured, then this configuration is in the registry and will be enabled.

Configuring the Network Load Balancing Driver
Network Load Balancing Properties Cluster Parameters Primary IP address Subnet mask Full Internet name cluster.domain.com Network address 02-bf Multicast support enabled Remote password Confirm password Remote control enabled Please consult on-line help for configuration information Host Parameters OK Port Rules Help Cancel Port Rules control response to traffic Host Parameters apply to default traffic Cluster Parameters apply to the cluster

When you enable the Network Load Balancing driver, you configure it to provide the type of service that is appropriate for your Network Load Balancing cluster plan. There are three tabs associated with the configuration, Cluster Parameters, Host Parameters, and Port Rules. Incorrect configuration can result in incorrect operation or prevent the host that is being configured from joining a cluster. You should plan what type of configuration you want to implement for the host before enabling and configuring the Network Load Balancing driver, because the type of service required, ports supported, IP addresses, and network configuration all influence the configuration parameters.

The Network Load Balancing driver checks configuration parameters entered in the Network Load Balancing Properties dialog box for validity. Cluster operations will not start if a problem is detected. All detected errors are reported in the Windows event log and are classified into the following categories. Event category Description Information events Record state transitions, such as driver startup, the completion of convergence, and the completion of cluster control actions. Warning events Record occurrences that do not prevent cluster operations. For example, a configuration problem, such as an invalid dedicated IP address or other parameter. Error events Record errors that can prevent cluster operations, such as configuration parameter problems, inconsistencies, or unexpected execution errors.

Network Load Balancing Properties
Cluster Parameters Network Load Balancing Properties Cluster Parameters Primary IP address Subnet mask Full Internet name cluster.domain.com Network address 02-bf Multicast support enabled Remote password Confirm password Remote control enabled Please consult on-line help for configuration information Host Parameters OK Port Rules Help Cancel Set Cluster IP Set Cluster Internet name Select Multicast Enable Remote Control

The Cluster Parameters tab contains the configuration elements associated with the virtual IP address, the Domain Name System (DNS) name for the host, the host mode (unicast or multicast), and the remote control password and permission.

To configure the Cluster Parameters tab:
Open Network and Dial-up Connections. Right-click Local Area Connection, and then click Properties. In the Local Area Connection Properties dialog box, click Network Load Balancing, and then click Properties. The Network Load Balancing Properties dialog box appears. On the Cluster Parameters tab, specify values for Primary IP address, Subnet mask, Full Internet name, Multicast support, and the remote options, such as Remote password, Confirm password, and Remote control, by using information from the installation checklist.

Primary IP Address and Subnet Mask
The primary address is a virtual IP address and must be set identically for all of the hosts in the cluster. You use this IP address to address the cluster as a whole, and it should be the IP address for the full Internet name that you specify for the cluster. The subnet mask must be identical on all cluster members, as they must be on the same subnet.

Full Internet Name The full Internet name specifies the full Internet name for the Network Load Balancing cluster. This name is used for the cluster as a whole, and should be the same for all hosts in the cluster, the DNS aliases, but this entry must resolve to the cluster virtual IP address.

Multicast Support By default, multicast is not selected, so the cluster will operate in unicast mode. When you select multicast, the network adapter associated with cluster operations will respond to two MAC addresses, one the internal MAC address, and the other a dynamically configured multicast address. All members of a cluster must use the same mode of operation, either unicast or multicast.

Remote Control By default, you must control all cluster hosts locally. If you plan on performing remote administration (start, stop, and configuration of the cluster members), you can enter and confirm a password for remote operations. You can only enable remote control by using the check box.

Selecting Unicast or Multicast Mode
Unicast Mode Multicast Mode Host Communication

Network Load Balancing can use one of two IP protocol configurations, unicast or multicast. By default, Network Load Balancing will use unicast. You must decide whether the unicast mode will be suitable for your cluster. Important: The Network Load Balancing service does not support a mixed unicast and multicast environment. All cluster hosts should be either multicast or unicast or the cluster will not function properly.

Network Load Balancing’s unicast mode induces switch flooding to simultaneously deliver incoming network traffic to all of the cluster hosts. Also, when Network Load Balancing uses multicast mode, switches often flood all of the ports by default to deliver multicast traffic. However, Network Load Balancing's multicast mode gives the administrator the opportunity to limit switch flooding by configuring a virtual LAN within the switch for the ports corresponding to the cluster hosts. You can configure a virtual LAN by manually programming the switch or by using the Internet Group Management Protocol (IGMP) or the Generic Attribute Registration Protocol Multicast Registration Protocol. Note: The current version of Windows Network Load Balancing does not provide automatic support for IGMP or Generic Attribute Registration Protocol Multicast Registration Protocol.

Unicast Mode The unicast operation uses a single MAC address for all of the operations involving the cluster adapter. Using a single MAC address has the side effect of disabling all communication between cluster hosts, because outgoing packets for another cluster host are sent to the same MAC address as the sender. These packets are then looped back within the sender stack and never reach the network.

Multicast Mode Multicast provides no significant advantage over unicast from a network traffic perspective, and the increased multicast processing overhead for routers and switches may lead to degraded or slower performance. You should carefully analyze the network impact when you use multicast to avoid congestion in other network devices.

Host Communication You will need to make decisions about host communications depending on your clustering plan. If communication between hosts is required, you can use: Unicast, if multiple NICs are installed in the host. Unicast is the recommended configuration that works in both routed and nonrouted environments. The configuration complexity is greater because it has multiple NICs and usually multiple subnets. Multicast, if a single NIC is installed in the host. Multicast imposes additional restrictions within a routed environment, in that the routers must handle multicast information. Verify that any routers in your network path will support cluster multicast Address Resolution Protocol (ARP) packets. Note: It is recommended that you use Unicast with multiple NICs for maximum flexibility in a routed environment.

Host Parameters Network Load Balancing Properties Cluster Parameters Priority (Unique host ID) 1 Initial cluster state active Dedicated IP address Subnet mask Host Parameters OK Port Rules Cancel Set Unique ID Set initial state Set Dedicated IP Address

The Host Parameters tab contains the configuration elements, which control the priority for default traffic, the start state for the cluster software, and the dedicated IP address for traffic that is not associated with load balancing.

To configure host parameters:
Click the Host Parameters tab in the Network Load Balancing Properties dialog box. Specify values for Priority (Unique host ID), Initial cluster state, Dedicated IP address, and Subnet mask by using information from your installation checklist. Note: Failure to set a Unique Host ID will result in the Network Load Balancing cluster failing to converge when another host with a new Unique Host ID is started.

Priority Priority specifies a host’s unique priority for handling default network traffic for TCP and User Datagram Protocol (UDP) ports that are not otherwise specified in an explicit port rule. The priority set for this host must be unique in the cluster, but does not require a contiguous series across the cluster members. The host with the highest priority (the lowest numerical value) among the current members of the cluster handles all of the cluster’s default network traffic. If this host fails or goes offline, the host with the next highest priority within the cluster takes over handling this network traffic.

Initial Cluster State The initial cluster state specifies whether Network Load Balancing should start and whether the host should immediately join the cluster when Windows 2000 is starting. If you must start other services and applications before cluster operations begin, you can clear this option so that the host will not join the cluster before you have properly configured its services and applications. You can then command a cluster host to join and leave the cluster by using the start and stop commands in the Network Load Balancing command- line control.

Dedicated IP Address and Subnet Mask
The dedicated IP address and subnet mask specify that the host’s IP address be used for network traffic that is not associated with the cluster (for example, Telnet access to a specific host within the cluster). The dedicated IP address is used to individually address each host in the cluster and should be unique for each host.

Port Rules Network Load Balancing Properties Cluster Parameters Port range 80 to 80 Host Parameters Port Rules Protocols TCP UDP Both Filtering mode Multiple hosts Single host Disabled Affinity None Single Class C Load weight 50 or Equal Handling priority 1 Add Modify Remove Start End Protocol Mode Priority Load Affinity 80 80 Both Multiple Equal None Both Multiple Equal None Set Port Range and Protocol for this rule Set or Modify parameters Add, Modify, or Remove a rule Select or view list of rules

The Port Rules tab maximizes control of the various types of inbound TCP/IP traffic by allowing you to configure the port rules to control the cluster network traffic. By default there is a single rule which handles all of the traffic that is inbound to the cluster virtual IP. You must modify or delete this rule, and create other rules to handle incoming traffic appropriately for your cluster plan.

When configuring port rules on multiple members of a cluster you must ensure that:
For every rule that you configure, you will select the applicable port range and protocols. You can set the port range to an individual port by entering the same value in both dialog boxes and you can set the protocol to TCP, UDP, or both. The rules that you enter on each host in the cluster must have matching filtering mode, affinity, and load weight and priority. If Network Load Balancing detects an inconsistent rule among the hosts in the cluster, it records a message in the Windows event log. The number and type of rules must exactly match for each host in the cluster. If a host attempts to join the cluster with a different number and type of rules from the other hosts, it will fail to go online and a message about the host status will be entered into the Windows event log. The following procedures describe how to create, modify, and delete the port rules.

To create a new port rule:
Click the Port Rules tab in the Network Load Balancing Properties dialog box. Specify values for Port range, Protocols, Filtering mode, Affinity, Load weight, and Handling priority using the information from your installation checklist. Click Add.

To modify an existing port rule:
Click the Port Rules tab in the Network Load Balancing Properties dialog box. Click the rule within the list of rules to display that rule’s parameters in the configuration area above the list of rules. Modify the Port range, Protocols, and Filtering mode parameters as required. Click Modify.

To delete a port rule: Click the Port Rules tab in the Network Load Balancing Properties dialog box. On the Port Rules tab, click the rule that you want to remove, and then click Remove.

Filtering Mode Network Load Balancing Properties Cluster Parameters Port range 80 to 80 Host Parameters Port Rules Protocols TCP UDP Both Filtering mode Multiple hosts Single host Disabled Affinity None Single Class C Load weight 50 or Equal Handling priority 1 Add Modify Remove Start End Protocol Mode Priority Load Affinity 80 80 Both Multiple Equal None Both Multiple Equal None Set Filtering mode For Single Host set Handling Priority

The filtering mode for Network Load Balancing is the method by which a cluster host handles a port’s inbound network traffic to the virtual IP address. The filtering mode can allow inbound traffic to be handled by multiple hosts, a single host, or discarded by a host. The filtering mode (rule) is applied to a numerical range of ports, by defining a port rule with a set of configuration parameters that define the filtering mode. The rules that you enter on each host in the cluster must have matching port ranges, protocol types, and filtering modes.

You can make three choices when deciding on the filtering mode for a Network Load Balancing cluster. They are outlined in following the table. Filtering Mode Action Multiple hosts Specifies that multiple hosts in the cluster handle network traffic for the associated port rule. Single host Specifies that a single host in the cluster, which is selected according to the specified priority, will handle network traffic for the associated port rule. Disabled Specifies that all network traffic for the associated port rule be blocked.

Your selection of multiple, single, or disabled hosts is based on the following information:
Select Multiple hosts when you want inbound traffic to be balanced across cluster members. This setting allows all cluster hosts to share, to a defined extent, all of the inbound client connection requests or UDP data streams. Select Single host when you want all inbound traffic to go to a single member of the cluster. The highest priority host will service all inbound traffic, and if this host fails, then the next highest priority host will handle all of the inbound traffic. This mode of operation provides fault tolerance without load balancing. Select Disabled when you wish to block traffic to a designated port. Blocking traffic allows you to build a firewall-like capability for TCP and UDP data at the Network Load Balancing driver. The filtering capability of the Windows 2000 TCP/IP stack allows additional filtering of inbound traffic, you can protect your application server from some forms of malicious attacks against the defined ports.

Creating rules to disable traffic handling can simplify protection by ensuring that traffic is discarded before being passed to the TCP/IP stack. Note: Filtering by using the disabled setting in a rule applies only to defined TCP and UDP traffic; other protocols, such as ICMP, are not disabled.

Affinity Network Load Balancing Properties Cluster Parameters Port range 80 to 80 Host Parameters Port Rules Protocols TCP UDP Both Filtering mode Multiple hosts Single host Disabled Affinity None Single Class C Load weight 50 or Equal Handling priority 1 Add Modify Remove Start End Protocol Mode Priority Load Affinity 80 80 Both Multiple Equal None Both Multiple Equal None Select Affinity mode for client IP

Depending on the application and client requirements of your Network Load Balancing cluster, you can be required to select an Affinity setting to control how multiple connections from a single client will be distributed in a load balancing cluster. By default affinity will be set to single after you install the Network Load Balancing driver. You implement affinity by directing all client requests from the same IP address, or a Class C group of addresses to the same cluster host.

The following table provides a summary of the affinity choices available to you.
Client Affinity Action None Network Load Balancing does not need to direct multiple requests from the same client to the same cluster host. Single Network Load Balancing should direct multiple requests from the same client IP address to the same cluster host. Single affinity is the default setting. Class C Network Load Balancing directs multiple requests from the same TCP/IP Class C address range to the same cluster host.

You will base your selection of None, Single, or Class C affinity on the following criteria:
Select None (no affinity) when you can distribute the client connections to any cluster member; for example, when load balancing a simple Hypertext Markup Language (HTML) based Web site or a virtual private network (VPN) server, all of the client connections can go to any cluster member. Select Single affinity where the same cluster host must service all connection requests from a single client, for example the same host must handle Hypertext Transfer Protocol (HTTP) connections and Hypertext Transfer Protocol Secure (HTTPS) connections from a client. Select Class C affinity where client connections can appear to come from different IP source addresses; for example when the Network Load Balancing cluster is isolated from the clients by a proxy array, Class C affinity would be the appropriate choice for the clustered environment. If you do not need this capability, select the Single affinity option instead to maximize scaled performance when using client affinity.

When making a decision to enable or disable client affinity use the following criteria:
Enabling either Single or Class C affinity ensures that only one cluster host handles all of the connections that are part of the same client session. Traffic handling by a single host is essential if the server program running on the cluster host maintains session state (such as server cookies) between connections. Disabling client affinity improves performance in a load balancing cluster because it allows different cluster hosts to concurrently handle multiple connections from the same client. To maximize scaled performance, disable client affinity (by using the None option) when it is not needed.

Load Weighting and Priority
Network Load Balancing Properties Cluster Parameters Port range 80 to 80 Host Parameters Port Rules Protocols TCP UDP Both Filtering mode Multiple hosts Single host Disabled Affinity None Single Class C Load weight 50 or Equal Handling priority 1 Add Modify Remove Start End Protocol Mode Priority Load Affinity 80 80 Both Multiple Equal None Both Multiple Equal None Select equal load distribution or manual load distribution

When designing a Network Load Balancing solution, you must decide how you will distribute the inbound client connections across the hosts. When using Multiple hosts filtering mode, you use Load Weight and host priority to determine how the Network Load Balancing cluster will handle the client request load. When you use the Single host filtering mode, the Network Load Balancing driver sets the Handling priority to determine the order each host will handle traffic for an associated port rule.

The following table shows the distribution mechanism based on load weight and priority settings.
Parameter Action Load Weight Specifies the percentage of load-balanced network traffic that this host should handle for the associated port rule. Allowed values range from 0 (zero) to 100. Equal Load Distribution Specifies that the host accept an equal portion of the load-balanced traffic in Multiple host filtering mode for the associated port rule. Handling Priority Specifies the local host's priority for handling the networking traffic for the associated port rule. The allowed values range from 1, the highest priority, to the maximum number of hosts allowed. This value must be unique for all of the hosts in the cluster.

Note: The sum of the load weights for all of the cluster hosts does not have to equal 100 because hosts can dynamically enter or leave the cluster. The actual fraction of traffic handled by each host is computed as the local load percentage value divided by the sum of all of the load weights across the cluster.

When making a decision to select Equal, Load weight, or a Handling priority value use the following criteria: Select Equal load weight when you require inbound traffic to be load balanced across a cluster and all of the members provide the same performance. Select Load Weight when you must balance inbound traffic across cluster members with different performance characteristics. Set a priority value when one cluster member will handle all of the inbound traffic, and other members provide fault tolerance.

Internet Protocol (TCP/IP) Properties
General You can get IP settings assigned automatically if your network supports this capability. Otherwise, you need to ask your network administrator for the appropriate IP settings. OK Cancel Obtain an IP address automatically Use the following IP address: IP address Subnet mask Default gateway Advanced… Obtain DNS server address automatically Use the following DNS server addresses: Preferred DNS server: Alternate DNS server: Enter cluster dedicated IP address for single NIC configuration, enter primary IP or dedicated IP addresses for multiple NIC configurations Enter additional IP addresses in the Advanced dialog box

You must add the IP addresses selected for the configuration of the Network Load Balancing driver to the properties of the TCP/IP stack. If your configuration has the recommended multiple network adapters operating in unicast mode, it is recommended that you place the dedicated IP address in the Internet Protocol (TCP/IP) Properties dialog box, with the default gateway, and the primary IP address in the Advanced TCP/IP Settings dialog box. Using the appropriate IP addresses will ensure that outbound traffic uses the dedicated adapter, minimizing non-client-to-cluster traffic on the cluster adapter.

To set up TCP/IP for Network Load Balancing on a single network adapter:
In the Local Area Connection Properties dialog box, click Internet Protocol (TCP/IP), and then click Properties. In IP address box, type the address that you entered as the Dedicated IP address in the Network Load Balancing Properties dialog box on the Host Parameters tab. In Subnet mask box, enter the subnet mask and default gateway information for your TCP/IP network. Click Advanced, and then click Add. Enter the cluster IP address in the space for the IP address, followed by the appropriate subnet mask, and, if necessary, default gateway. This IP address corresponds to the cluster's Primary IP address that you entered in the Network Load Balancing Properties dialog box on the Cluster Parameters tab.

If you need to configure additional virtual IP addresses for your cluster (for example, if you are running a multihomed Web server), you can do so in the Advanced TCP/IP Settings dialog box. Note: It is essential that you enter the dedicated IP address first, in the Internet Protocol (TCP/IP) Properties dialog box (not in the Advanced TCP/IP Settings dialog box). This configuration allows all outbound connections made on behalf of this host (for example, Telnet or File Transfer Protocol (FTP)) to be initiated with this address.

To set up TCP/IP for Network Load Balancing on multiple network adapters:
In the Local Area Connection Properties dialog box, click Internet Protocol (TCP/IP), and then click Properties. In IP address, type the address that you entered as the Primary IP address in the Network Load Balancing Properties dialog box on the Cluster Parameters tab. You can also enter the dedicated IP address (corresponds to the dedicated IP address that you entered in the Network Load Balancing Properties dialog box on the Host Parameters tab) in this box. You will then enter the cluster's primary IP address in the Advanced TCP/IP Settings dialog box. In the Subnet mask box, enter the subnet mask and default gateway information for your TCP/IP network.

Note: If you use the dedicated IP address, ensure this address appears first, in the Internet Protocol (TCP/IP) Properties dialog box. If you need to configure additional virtual IP addresses for your cluster (for example, if you are running a multihomed Web server), click Advanced and then click Add. You can then specify additional virtual IP addresses for this network adapter and provide other information as necessary.

Post-Installation Configuration
Internet Protocol (TCP/IP) Properties General You can get IP settings assigned automatically if your network supports this capability. Otherwise, you need to ask your network administrator for the appropriate IP settings. OK Cancel Obtain an IP address automatically Use the following IP address: IP address Subnet mask Default gateway Advanced… Obtain DNS server address automatically Use the following DNS server addresses: Preferred DNS server: Alternate DNS server: Network Load Balancing Properties Cluster Parameters Port range 80 to 80 Host Parameters Port Rules Protocols TCP UDP Both Filtering mode Multiple hosts Single host Disabled Affinity None Single Class C Load weight 50 or Equal Handling priority 1 Add Modify Remove Start End Protocol Mode Priority Load Affinity 80 80 Both Multiple Equal None Both Multiple Equal None

When the installation and configuration of the Network Load Balancing driver is complete, the parameters used to define the cluster operation are stored in the registry. For the majority of management operations you will use the driver properties user interface (UI) and the TCP/IP Properties dialog box to make changes to the Network Load Balancing operation. If you are required to make changes that have no corresponding UI component, for example when doing detailed tuning, you can be required to make changes directly in the registry.

Network Load Balancing registry information is stored under the
HKEY_LOCAL_MACHINE\SYSTEM\ CurrentControlSet\Services\ WLBS\Parameters subkey. Important: Do not make changes in the registry values unless you are sure that the changes are required. Incorrect settings can disable the driver. Before you edit the registry, make sure that you understand how to restore it if a problem occurs.

In tuning Network Load Balancing, the most common element that can require registry changes is the heartbeat message timing. A longer message exchange period will reduce the networking overhead that is needed to maintain fault tolerance, but it will increase the failover delay. Likewise, increasing the number of message exchanges prior to convergence will reduce the number of unnecessary convergence initiations because of transient network congestion, but will also increase the failover delay time. Using the default values, five seconds are needed to discover a missing host, and the cluster needs another five seconds to redistribute the load. A total of ten seconds to complete failover should be acceptable for most TCP/IP programs.

The default values for redistribution of the cluster are:
By default, the time period a cluster host waits before sending the next heartbeat is one second. Adjusting the AliveMsgPeriod registry parameter can customize the time between heartbeats. By default, a cluster host is declared inactive by the other hosts if its heartbeat is missed for five periods. You can customize this value by adjusting the AliveMsgTolerance registry parameter. You should pick the settings for AliveMsgTolerance and AliveMsgPeriod that are based on your failover requirements.

Lab A: Installing and Configuring the Network Load Balancing Driver

Objectives After completing this lab, you will be able to install and configure the Network Load Balancing driver.

Scenario You will commence the lab with nothing installed except Windows 2000 Advanced Server with Internet Information Services (IIS) and File Transfer Protocol (FTP). You will work in pairs to configure and test computers, verify the operation of the Web services and then install the Network Load Balancing driver. You will then work individually to test the Network Load Balancing cluster that you created (the cluster will have only one member). Finally, you will -reconfigure and test the cluster by working with another student to create two member clusters.

Exercise 1: Checking Networking Configuration
In this exercise, you will check the IP configuration of the network cards. All of the students will complete this procedure and do not need to work with a partner. The students will collect information about the network adapters in their computers.

To discover and document current network settings
Right-click on My Network Places and select Properties to open Network and Dial-up Connections. Double-click on the first network adapter in Network and Dial-up Connections and record the following information from the General tab of the Local Area Connection status: Note: Local Area Connection may have been renamed. Use the currently assigned name.

Information to Collect Collected Information
a. Connection Status ______________________________ b. Connection Speed ______________________________ c. Adapter Name ______________________________ Note: If the Connection Status is Not Connected, your card will not function.

Click Properties in the Local Area Connection status.
Select Internet Protocol (TCP/IP), and then click Properties. Record the following information from the Internet Protocol (TCP/IP Properties dialog box.

a. IP Address ______________________________ (If configured to use DHCP, enter Automatic) b. Subnet Mask ______________________________

Close all of the pages to return to Network and Dial-up Connections.
Double-click on the second network adapter in Network and Dial-up Connections and record the following information from the General tab of the Local Area Connection status. Note: Local Area Connection may have been renamed. Use the currently assigned name and record this information.

a. Connection Status ______________________________ b. Connection Speed ______________________________

Click Properties in the Local Area Connection status.
Select Internet protocol (TCP/IP), and then click Properties. Record the following information from the Internet Protocol (TCP/IP) Properties dialog box. Note: The adapter with a statically assigned address, which is connected to this classroom network, will be used as the Network Load Balancing adapter.

a. IP Address ______________________________ (If configured to use DHCP, enter Automatic) b. Subnet Mask ______________________________ Note: The adapter with a statically assigned address, which is connected to the classroom network, will be used as the Network Load Balancing adapter. If you have more than two adapters with statically assigned addresses the instructor will advise which adapter to use.

Exercise 2: Checking Current MAC Addresses for Network Adapters
In this exercise, you will identify and record the MAC addresses of the cards. All students will complete this procedure and do not need to work with a partner to complete the procedure. The students will collect information on the MAC addresses for network adapters on their computer. Note: In subsequent exercises this information will be shared with a partner.

To discover the MAC address by using Ipconfig
Click Start, click Run, and then type cmd in the Run dialog box. Click OK to open a command window. At the command prompt, type Ipconfig /all and then press ENTER. Record the Physical Address and IP Address for the network adapters.

a. Physical Address for Adapter 1 ______________________________ b. IP Address for Adapter ______________________________ c. Physical Address for Adapter 2 ______________________________ d. IP Address for Adapter ______________________________

To discover the MAC address by using Ping and ARP
Ask your partner for the IP address of their network adapters. Information to Collect Collected Information a. IP Address for Partner Adapter 1 ______________________________ b. IP Address for Partner Adapter 2 ______________________________

Click Start, click Run, and type cmd in the Run dialog box.
Click OK to open a command window. At the command prompt, type Ping partner Adapter 1 IP address and then press ENTER. At the command prompt, type Ping partner Adapter 2 IP address and then press ENTER. At the command prompt, type Arp –a Record the Physical Address for the network adapters.

Close all of the command windows.
Information to Collect Collected Information a. Physical Address for Partner Adapter 1 ________________________ b. Physical Address for Partner Adapter 2 ________________________ Close all of the command windows.

Exercise 3: Accessing a Student Partner Web Page
You will work with a partner to complete this procedure. You will use Internet Explorer to access a Web page on your partner’s computer.

To access your partner’s Web page
On the desktop, double-click Internet Explorer. Ask your partner for the IP address of their computer. In the Address dialog box enter the IP address of your partner’s computer. A web page with text indicating your partner’s number should appear in Microsoft Internet Explorer. Close Internet Explorer.

Exercise 4: Installing and Configuring the Network Load Balancing Driver
In this exercise, you will: Use the Planning Worksheet that is provided to configure the Network Load Balancing driver by entering the required information in the wizard. Update the TCP/IP properties to include the required Network Load Balancing addresses. Reconfigure the Web site to use the cluster address. Test the Web site and record information on the operation of the cluster.

All students will complete this procedure and do not need to work with a partner. You will install Network Load Balancing and reconfigure your Web site to use the cluster virtual IP address.

To install and configure the Network Load Balancing driver
Right click My Network Places and then click Properties. Double-click on the network adapter that you will use to install Network Load Balancing. Click Properties in the Local Area Connection status dialog box. In the Local Area Connection Properties dialog box, select the Network Load Balancing driver check box. Note: If Network Load Balancing is not shown in the list, click Install, select Service and then select Network Load Balancing to add to the list.

Click Properties to open the Network Load Balancing Properties dialog box.
Using the supplied Planning Worksheet for Exercise 4, enter the information in the Cluster Parameters, Host Parameters and Port Rules properties dialog boxes. When all of the information is entered, click OK in the Network Load Balancing Properties dialog box. In the Local Area Connection Properties dialog box select Internet Protocol (TCP/IP), and then click Properties. In the Internet Protocol (TCP/IP) Properties dialog box, ensure that the dedicated IP address and subnet mask of the cluster is entered in the Use the following IP address dialog boxes from the reference sheet at the end of this exercise.

Click Advanced, and in the Advanced TCP/IP Settings page, add the cluster IP address and subnet mask to the IP Addresses list. Note: If you receive a dialog box advising that WINS is not configured, click Yes to continue. Click OK in the Local Area Connection Properties dialog box to activate the Network Load Balancing driver. Close the Local Area Connection status dialog box.

To check that the Network Load Balancing driver is functional
Click Start, point to Programs, point to Administrative Tools, and then click Event Viewer to start the Event Viewer Microsoft Management Console (MMC). Examine the System Log and look for events from a source of Windows Load Balancing Service (WLBS). Record the event ID’s, and examine the events to discover if there is an indication that your cluster is working correctly. Note: If you have Error events for Wlbs in your System Log, advise your instructor.

When your partner is at the same point in the procedures, ask your partner for the cluster and dedicated IP Address for their Network Load Balancing network adapter. Information to Collect Collected Information a. Cluster IP Address for Partner ____________________________ b. Dedicated IP Address for Partner ____________________________

Click Start, click Run, and then type cmd in the Run dialog box.
Click OK to open a command window. At the command prompt, type Ping partner Cluster IP address and then press ENTER. At the command prompt, type Ping partner Dedicated IP address and then press ENTER. At the command prompt, type Arp –a Record the Physical Address associated with the Cluster IP and Dedicated IP Address of your partner.

Information to Collect Collected Information a. Physical Address for Partner Cluster ________________________ IP b. Physical Address for Partner ____________________________ Dedicated IP Close all of the command windows. Note: If the cluster is configured for Unicast, both addresses will be the same; if it is configured for Multicast, the addresses will be different.

To configure the Default Web site to use the cluster IP address
Click Start, point to Programs, point to Administrative Tools, and then click Internet Services Manager. In the Internet Information Services console, expand the local host icon, right-click Default Web Site, and then select Properties. In the Default Web Site Properties dialog box, select the Web Site tab and in the IP address dialog drop- down list, select the cluster virtual IP address. By default the IP address will be set to (All Unassigned). Click OK to close the Default Web Site Properties dialog box. Close Internet Services Manger console.

To test that the Web site is using the correct IP address
Use Internet Explorer to access both the cluster IP address and the dedicated IP address of your local computer. Document the result in the following area: a. Accessing the cluster IP address (a page should display correctly). b. Accessing the dedicated IP address (an HTTP 404 error should occur). Use Internet Explorer to access both the virtual IP address and the dedicated IP address of your partner’s computer. Document the results in the following area: b. Accessing the dedicated IP address (an error indicating no site at this address should occur).

Exercise 5: Configuring a Multihost Network Load Balancing Cluster
All students complete this procedure with a partner. You will reconfigure the Network Load Balancing driver to create a two-host cluster and reconfigure your Web site to use the cluster IP address. Students will complete the procedure on the lowest number student ID computer first, and then complete the process on the other student computer.

To reconfigure a student host to be the first member of the multihost cluster
Double-click the network adapter that is used for Network Load Balancing. Click Properties in the Local Area Connection status dialog box. In the Local Area Connection Properties dialog box, select Network Load Balancing. Click Properties to open the Network Load Balancing Properties dialog box. Using the supplied Planning Worksheet, enter the information in the Cluster Parameters, Host Parameters and Port Rules properties dialog boxes.

Ensure that the Initial cluster state is selected on the Host Parameters dialog box.
When all of the information is entered, click OK in the Network Load Balancing Properties dialog box. In the Local Area Connection Properties dialog box, select Internet Protocol (TCP/IP), and then click Properties. In the Internet Protocol (TCP/IP) Properties dialog box, ensure that the dedicated IP address and subnet mask of the cluster is entered in the Use the following IP Address dialog boxes. Click Advanced, and in the Advanced TCP/IP Settings dialog box, add the cluster IP address and subnet mask to the IP Addresses list.

Click OK in the Local Area Connection Properties dialog box to activate the Network Load Balancing driver. Close the Local Area Connection status dialog box. Click Start, point to Programs, point to Administrative Tools, and then click Event Viewer to start the Event Viewer MMC. Examine the System Log and look for events from a source of WLBS. Record the event ID’s, and examine the events to determine that your cluster is working correctly.

____________________________________________________________
Note: If you have Error events for Wlbs in your System Log, advise your instructor.

To verify that the Network Load Balancing driver is functional
Note: Complete this procedure on the higher number student ID computer. Use the cluster and dedicated IP Address for the Network Load Balancing network adapter on the lower number student ID. Information to Collect Collected Information a. Cluster IP Address ______________________________ b. Dedicated IP Address ______________________________

Click OK to open a command window. At the command prompt, type Ping partner Cluster IP address and then press ENTER. At the command prompt, type Ping partner Dedicated IP address and then press ENTER. At the command prompt, type Arp -a Record the Physical Address associated with the Cluster IP and Dedicated IP Address of the lower number student ID computer.

____________________________________________________________
Information to Collect Collected Information a. Physical Address Cluster IP ____________________________ b. Physical Address Dedicated IP ____________________________ Compare the MAC addresses recorded previously with the results obtained in Exercise 2 and explain the differences. ____________________________________________________________ The MAC address associated with the cluster virtual IP is shown as 03-bf-xx-xx-xx-xx because it is now a multicast MAC address. The dedicated IP address is the MAC address of the card (the hard- wired address).

To configure the default Web site to use the cluster IP address
Note: Complete this procedure on the lower number student ID computer. Click Start, point to Programs, point to Administrative Tools, and then click Internet Services Manager. In the Internet Information Services console expand the local host icon, and right-click the Default Web Site, and then select Properties. In the Default Web Site Properties dialog box, select the Web Site tab and in the IP Address drop-down list, select the cluster virtual IP address. The IP address will be set to the value that was used in Exercise 4. Click OK to close the Default Web Site Properties dialog box. Close the Internet Service Manager console.

Note: Complete this procedure from the higher numbered student ID computer. • Use Internet Explorer to access both the virtual IP address and the dedicated IP address of the lower number student ID computer local computer. Document the results in the following area: a. Accessing the virtual IP address (a page should display correctly). b. Accessing the dedicated IP address (an HTTP 404 error should occur).

To reconfigure the second student computer to be a member of the cluster
Students will complete the following procedure on the higher number student ID computer. Double-click the network adapter that is used for Network Load Balancing. Click Properties in the Local Area Connection status dialog box. In the Local Area Connection Properties dialog box, select Network Load Balancing. Click Properties to open the Network Load Balancing Properties dialog box. Using the supplied Planning Worksheet, enter the information in the Cluster Parameters, Host Parameters, and Port Rules properties dialog boxes.

Ensure that the Initial cluster state is selected in the Host Parameters dialog box.
When all of the information is entered, click OK in the Network Load Balancing Properties dialog box. In the Local Area Connection Properties dialog box, select Internet Protocol (TCP/IP), and then click Properties. In the Internet Protocol (TCP/IP) Properties dialog box, ensure that the dedicated IP address and subnet mask of the cluster is entered in the Use the following IP Address dialog boxes. Click Advanced, and in the Advanced TCP/IP Settings dialog box, add the cluster IP address and subnet mask to the IP Addresses list.

Click OK in the Local Area Connection Properties dialog box to activate the Network Load Balancing driver. Close the Local Area Connection status dialog box. Click Start, point to Programs, point to Administrative Tools, and then click Event Viewer to start the Event Viewer MMC. Examine the System Log and look for events from a source of WLBS. Record the event ID’s, and examine the events to discover if there is an indication that your cluster is working correctly. Note: If you have Error events for Wlbs in your System log, advise your instructor.

To verify that the Network Load Balancing driver is functional
Note: Complete this procedure on the lower number student ID computer. Use the Cluster and Dedicated IP Address for the Network Load Balancing network adapter on the higher number student ID. Information to Collect Collected Information a. Cluster IP Address ______________________________ b. Dedicated IP Address ______________________________

Click OK to open a command window. At the command prompt, type Ping partner Cluster IP address and then press ENTER. At the command prompt, type Ping partner Dedicated IP address and then press ENTER. Was the Ping command to the addresses successful? At the command prompt, type Arp –a

Record the Physical Address associated with the Cluster IP and Dedicated IP address of the higher number student ID computer. Information to Collect Collected Information a. Physical Address Cluster IP ____________________________ b. Physical Address Dedicated IP ____________________________ Compare the MAC addresses that were recorded previously with the results that were obtained in Exercise 2 and explain the differences.

____________________________________________________________ The MAC address of the cluster IP is not shown in the Arp -a listing because the IP address is also the local computer IP address; so the ping did not result in traffic on the network. Only the dedicated IP of the high number student computer is shown. Close all of the command windows.

To configure the default Web site to use the cluster IP address
Note: Complete this procedure on the higher number student ID computer. Click Start, point to Programs, point to Administrative Tools, and then click Internet Service Manager. In the Internet Information Services console expand the local host icon, and right-click the Default Web Site, and then select Properties. In the Default Web Site Properties dialog box, select the Web Site tab and in the IP Address drop-down list, select the cluster virtual IP address. The IP address will be set to the value used in Exercise 4. Click OK to close the Default Web Site Properties dialog box. Close the Internet Service Manager console.

Note: Complete this procedure from both the lower and higher numbered student ID computers. • Use Internet Explorer to access both the virtual IP address and the dedicated IP address of the local computer of the lower number student ID computer. Document the results in the following area: a. Accessing the virtual IP address (a page should display correctly). b. Accessing the dedicated IP address (an HTTP 404 error should occur).

Explain the different results obtained from the lower and higher numbered student computers.
____________________________________________________________ Both students access the Web site by using the virtual IP address, because this is the local IP address for the computer, the HTTP request is not sent on the network and is fulfilled by the local computer.

Review Pre-Installation Network Load Balancing Driver Installation
Configuring the Network Load Balancing Driver Cluster Parameters Port Rules TCP/IP Properties Post-Installation Configuration

Module 9: Installing and Configuring Network Load Balancing

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Module 9: Installing and Configuring Network Load Balancing

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