Features in Network Load Balancing
NLB includes the following features:
Scalability
Scalability is the measure of how well a computer, service, or application can grow to meet increasing performance demands. For NLB clusters, scalability is the ability to incrementally add one or more systems to an existing cluster when the overall load of the cluster exceeds its capabilities. To support scalability,
NLB can do the following:
Balance load requests across the NLB cluster for individual TCP/IP services.
Support up to 32 computers in a single cluster.
Balance multiple server load requests (from either the same client or from several clients) across multiple hosts in the cluster.
Support the ability to add hosts to the NLB cluster as the load goes up, without bringing the cluster down.
Support the ability to remove hosts from the cluster when the load goes down.
Enable high performance and low overhead through fully pipelined implementation. Pipelining allows requests to be sent to the NLB cluster without waiting for response to the previously sent one.
High-availability :
A highly available system reliably provides an acceptable level of service with minimal downtime. To provide high availability, NLB includes built-in features that can automatically:
Detect and recover from a cluster host that fails or goes offline.
Balance the network load when hosts are added or removed.
Recover and redistribute the workload within ten seconds.
Manageability :
NLB provides the following manageability features:
You can manage and configure multiple NLB clusters and the cluster hosts from a single computer by using NLB Manager.
You can specify the load balancing behavior for a single IP port or group of ports by using port management rules.
You can define different port rules for each Web site. If you use the same set of load-balanced servers for multiple applications or Web sites, port rules are based on the destination virtual IP address (using virtual clusters).
You can direct all client requests to a single host by using optional, single-host rules. NLB routes client requests to a particular host that is running specific applications.
You can block undesired network access to certain IP ports.
You can enable Internet Group Management Protocol (IGMP) support on the cluster hosts to control switch flooding (when operating in multicast mode).
You can remotely start, stop, and control NLB actions from any networked computer that is running Windows by using shell commands or scripts.
You can view the Windows event log to check NLB events. NLB logs all actions and cluster changes in the event log.
Ease-of-use
NLB provides many features that make it convenient to use:
NLB is installed as a standard Windows networking driver component.
NLB requires no hardware changes to enable and run.
NLB Manager enables you to create new NLB clusters.
NLB Manager enables you to configure and manage multiple clusters and all of the cluster's hosts from a single remote or local computer.
NLB lets clients access the cluster by using a single, logical Internet name and virtual IP address—known as the cluster IP address (it retains individual names for each computer). NLB allows multiple virtual IP addresses for multihomed servers.
Note
In the case of virtual clusters, the servers do not need to be multihomed to have multiple virtual IP addresses.
NLB can be bound to multiple network adapters, which allows you to configure multiple independent clusters on each host. Support for multiple network adapters differs from virtual clusters in that virtual clusters allow you to configure multiple clusters on a single network adapter.
You do not have to modify server applications to run in an NLB cluster.
If a cluster host fails and then is subsequently brought back online, NLB can be configured to automatically add that host to the cluster. The added host will then be able to start handling new server requests from clients.
You can take computers offline for preventive maintenance without disturbing cluster operations on the other hosts.
NLB includes the following features:
Scalability
Scalability is the measure of how well a computer, service, or application can grow to meet increasing performance demands. For NLB clusters, scalability is the ability to incrementally add one or more systems to an existing cluster when the overall load of the cluster exceeds its capabilities. To support scalability,
NLB can do the following:
Balance load requests across the NLB cluster for individual TCP/IP services.
Support up to 32 computers in a single cluster.
Balance multiple server load requests (from either the same client or from several clients) across multiple hosts in the cluster.
Support the ability to add hosts to the NLB cluster as the load goes up, without bringing the cluster down.
Support the ability to remove hosts from the cluster when the load goes down.
Enable high performance and low overhead through fully pipelined implementation. Pipelining allows requests to be sent to the NLB cluster without waiting for response to the previously sent one.
High-availability :
A highly available system reliably provides an acceptable level of service with minimal downtime. To provide high availability, NLB includes built-in features that can automatically:
Detect and recover from a cluster host that fails or goes offline.
Balance the network load when hosts are added or removed.
Recover and redistribute the workload within ten seconds.
Manageability :
NLB provides the following manageability features:
You can manage and configure multiple NLB clusters and the cluster hosts from a single computer by using NLB Manager.
You can specify the load balancing behavior for a single IP port or group of ports by using port management rules.
You can define different port rules for each Web site. If you use the same set of load-balanced servers for multiple applications or Web sites, port rules are based on the destination virtual IP address (using virtual clusters).
You can direct all client requests to a single host by using optional, single-host rules. NLB routes client requests to a particular host that is running specific applications.
You can block undesired network access to certain IP ports.
You can enable Internet Group Management Protocol (IGMP) support on the cluster hosts to control switch flooding (when operating in multicast mode).
You can remotely start, stop, and control NLB actions from any networked computer that is running Windows by using shell commands or scripts.
You can view the Windows event log to check NLB events. NLB logs all actions and cluster changes in the event log.
Ease-of-use
NLB provides many features that make it convenient to use:
NLB is installed as a standard Windows networking driver component.
NLB requires no hardware changes to enable and run.
NLB Manager enables you to create new NLB clusters.
NLB Manager enables you to configure and manage multiple clusters and all of the cluster's hosts from a single remote or local computer.
NLB lets clients access the cluster by using a single, logical Internet name and virtual IP address—known as the cluster IP address (it retains individual names for each computer). NLB allows multiple virtual IP addresses for multihomed servers.
Note
In the case of virtual clusters, the servers do not need to be multihomed to have multiple virtual IP addresses.
NLB can be bound to multiple network adapters, which allows you to configure multiple independent clusters on each host. Support for multiple network adapters differs from virtual clusters in that virtual clusters allow you to configure multiple clusters on a single network adapter.
You do not have to modify server applications to run in an NLB cluster.
If a cluster host fails and then is subsequently brought back online, NLB can be configured to automatically add that host to the cluster. The added host will then be able to start handling new server requests from clients.
You can take computers offline for preventive maintenance without disturbing cluster operations on the other hosts.
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