Every day this week the Clustering & High-Availability is writing about some of the top questions we get about Network Load Balancing (NLB) in Windows Server 2008 R2.  We hope you find these helpful!

 

·         Monday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040072.aspx

·         Tuesday: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx

 

Gary Jackman

Software Test Engineer

Network Load Balancing

Microsoft

 

 

Can I run mixed clusters containing both physical servers and VMs as NLB nodes?

Yes.  However, all servers and Virtual Machines (VMs) must be on the same VLAN and IP subnet.

 

 

What is a port rule?

A port rule is a set of parameters which NLB uses to load balance traffic.  It determines how each port’s NLB network traffic is handled.  The default port rule is defined as:

 

Filtering Mode

Multiple

VIP

 ALL

Start Port

0

End Port

65535

Protocol

BOTH

Affinity

Single


 

Depending on the deployment requirements, the user can define port rule per application, or per service which is being load balanced.

 

For example, if you had a web service that hosted both stateless HTTP (port 80) and HTTPS (port 443) you would want to configure two port rules.

 

 

Filtering Mode

Multiple

VIP

 ALL

Start Port

80

End Port

80

Protocol

TCP

Affinity

NONE

 

 

Filtering Mode

Multiple

VIP

 ALL

Start Port

443

End Port

443

Protocol

TCP

Affinity

Single

 

Alternatively if you had a web service had both stateful and stateless HTTP, as well as HTTPS, you could configure three port rules and assign a VIP to the port rules.

 

In the following example, three VIPs are required.

·         VIP1 belongs to the web service that hosts the stateful HTTP

·         VIP2 belongs to the web service that hosts the stateless HTTP

·         For HTTPS you don’t need to assign two separate VIPs as the ALL will apply to all VIPs

 

Filtering Mode

Multiple

VIP

 VIP1

Start Port

80

End Port

80

Protocol

TCP

Affinity

Single

 

Filtering Mode

Multiple

VIP

 VIP2

Start Port

80

End Port

80

Protocol

TCP

Affinity

NONE

 

Filtering Mode

Multiple

VIP

 ALL

Start Port

443

End Port

443

Protocol

TCP

Affinity

Single

 

It should be noted that the three port rule only cover 80 and 443.  Any other traffic destined to the cluster VIP will still be handed, but only by the default host.  For example, if a user attempted to FTP to the cluster VIP and FTP was enabled, the default host will be the only host which accepts the connections.

 

More information about creating and configuring port rules: http://blogs.msdn.com/b/clustering/archive/2010/07/20/10040467.aspx