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Example: Controlling the Distribution of Client Traffic Within the Cluster

Updated: March 28, 2003

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

An organization implements the following solutions, which include Network Load Balancing, to reduce outages and improve performance:

  • VPN remote access, based on Routing and Remote Access

  • E-commerce Web applications, based on IIS 6.0

  • A customer support FTP site, based on IIS 6.0

VPN remote access solution with Routing and Remote Access

The VPN remote access solution, based on Routing and Remote Access, provides remote access to the organization’s private network by establishing PPTP and L2TP VPN tunnels through the Internet.

The VPN remote access server farm contains five servers that have identical system resources. Network Load Balancing is enabled on the network adapters connected to the Internet. A cluster IP address has been configured for the cluster, and the appropriate DNS entries have been determined but not yet created.

Because the default port rule provides the appropriate affinity and load balancing, no custom port rules are required for the cluster.

E-commerce Web application solution with IIS 6.0

The e-commerce Web application solution, based on IIS 6.0, includes the following applications:

  • Web-based, e-commerce application built with static HTML

  • Web-based, e-commerce application built with ASP

Both applications use:

  • HTTPS (TCP port 443)

  • HTTP (TCP Port 80)

The application that uses ASP maintains user session information after the user is authenticated.

The two e-commerce Web application solutions are combined on the same IIS 6.0 Web farm and, subsequently, the same Network Load Balancing cluster. The IIS 6.0 Web farm contains four computers that have identical system resources. Network Load Balancing is enabled on the network adapters connected to the Internet. A cluster IP address is configured for the cluster, and the appropriate DNS entries have been determined but not yet created.

To facilitate the combination of the two e-commerce Web applications into a single Web farm and cluster, each e-commerce application is assigned to a virtual cluster. By assigning each e-commerce application to a virtual cluster, client access can be stopped individually to allow operations tasks, such as upgrades, to be performed without disrupting client access to the other e-commerce application.

Table 8.12 lists the cluster, virtual cluster, and cluster hosts in the organization’s e-commerce solution.

Table 8.12   Network Load Balancing Clusters and Cluster Hosts in the E-Commerce Solution

 

Cluster Name Solution Type Cluster Host

NLBCluster-B

Web-based, e-commerce applications

Cluster

  • NLBClusterB-01

  • NLBClusterB-02

  • NLBClusterB-03

  • NLBClusterB-04

VirCluster-A

IIS 6.0 and HTML

Virtual cluster

Same as NLBCluster-B

VirCluster-B

IIS 6.0 and ASP

Virtual cluster

Same as NLBCluster-B

Table 8.13 lists the port rules that meet the requirements of the e-commerce Web application solution that includes IIS 6.0 and Network Load Balancing.

Table 8.13   Port Rules for IIS 6.0 E-Commerce Solution on NLBCluster-B

 

Cluster IP Address Start End Protocol Filtering Mode Load Weight Affinity

VirtualIP-A

80

80

TCP

Multiple

Equal

None

VirtualIP-A

443

443

TCP

Multiple

Equal

Single

VirtualIP-B

80

80

TCP

Multiple

Equal

Single

VirtualIP-B

443

443

TCP

Multiple

Equal

Single

Because the port rules, listed in Table 8.13, have a specified load weight of Equal, the same port rules are used for all the cluster hosts. The virtual clusters, VirtualIP-A and VirtualIP-B, are dedicated to the respective e-commerce applications. Because both applications use HTTP (TCP port 80) and HTTPS (TCP port 443), port rules must be specified for each protocol in each virtual cluster.

Customer support FTP site solution with IIS 6.0

The customer support FTP site solution:

  • Is based on IIS 6.0.

  • Provides secured and unsecured access to files.

  • Allows users to upload files to specified areas on the FTP site.

  • Requires file uploads that are centralized on one FTP server to avoid users uploading duplicate files.

  • Uses TCP port 20 for FTP.

  • Uses TCP port 21 for FTP.

The customer support FTP site runs on an IIS 6.0 farm and, subsequently, a Network Load Balancing cluster. The IIS 6.0 farm contains three computers that have identical system resources. Network Load Balancing is enabled on the network adapters connected to the Internet. A cluster IP address has been configured for the cluster, and the appropriate DNS entries have been determined but not yet created.

To support the number of simultaneous users who are performing FTP downloads, all FTP download requests must be load balanced across the entire IIS 6.0 farm. However, to ensure that users upload files to only one location, FTP uploads must be directed to only one server in the IIS 6.0 farm.

To facilitate the differences in cluster host affinity between FTP uploads and downloads, each direction of FTP transfer is assigned to a different virtual cluster. By assigning FTP uploads to a virtual cluster and FTP downloads to another virtual cluster, the organization ensures that FTP downloads can be load balanced across all cluster hosts, while FTP uploads are sent to only one cluster host in the cluster.

Table 8.14 lists the cluster, virtual cluster, and cluster hosts selected in the organization’s customer support FTP site solution.

Table 8.14   Clusters and Cluster Hosts in the Customer Support FTP Site Solution

 

Cluster Name Solution Type Cluster Host

NLBCluster-C

FTP site

Cluster

  • NLBClusterC-01

  • NLBClusterC-02

  • NLBClusterC-03

VirCluster-C

FTP download

Virtual cluster

All cluster hosts can be used for download.

VirCluster-D

FTP upload

Virtual cluster

NLBClusterC-03 is to be used for upload.

Table 8.15 lists the port rules that meet the requirements of the organization’s customer support FTP site solution, which includes IIS 6.0 and Network Load Balancing.

Table 8.15   Port Rules for an IIS 6.0 FTP Site Solution on NLBCluster-C

 

Cluster IP Address Start End Protocol Filtering Mode Load Weight Affinity Handling Priority

VirtualIP-C

20

21

TCP

Multiple Hosts

Equal

Single

NA

VirtualIP-D

20

21

TCP

Single Host

   
  • NLBClusterC-03 = 1

  • NLBClusterC-01 = 2

  • NLBClusterC-02 = 3

The port rules that define VirCluster-C are identical for all the cluster hosts in NLBCluster-C. The port rules that define VirCluster-D are unique for each cluster host in NLBCluster-C, because the handling priority for each cluster host is unique. NLBClusterC-03 is the cluster host that is designated for FTP uploads, and it is assigned a handling priority of 1 to ensure that all file uploads are sent to NLBClusterC-03. The handling priority for NLBClusterC-01 and for NLBClusterC-02 must be unique and of a lower priority than for NLBClusterC-03.

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