Module 13: Network Load Balancing Fundamentals

Module 13: Network Load Balancing Fundamentals

• Server Availability and Scalability Overview

• Windows Network Load Balancing

• Configuring Windows Network Load Balancing

Lesson 1: Server Availability and Scalability Overview

• What Is Availability?

• What Is Scalability?

• What Is Load Balancing?

• Comparing Hardware and Software Load Balancing

• What Is Failover Clustering?

What Is Availability?

Availability is a level of service that applications, services, or systems provide, expressed as a percentage of time

Highly available services or systems are available more than 99% of the time

Availability is a level of service that applications, services, or systems provide, expressed as a percentage of time

Highly available services or systems are available more than 99% of the time

High availability:

•Requirements differ based on how availability is measured

•Does not typically include planned outages when calculating availability

What Is Scalability?

Scalability measures the ability to increase capacityScalability measures the ability to increase capacity

Scaling up:

• Increases the capacity of a single server

• Involves adding more or better hardware to a server

Scaling out:

• Increases the capacity of an application

• Involves adding additional servers to perform processing

What Is Load Balancing?

Load Balancing is a system that increases the scalability and availability of the servers that provide access to data

Load Balancing is a system that increases the scalability and availability of the servers that provide access to data

Other load balancing methods:

•A virtual IP address is used to distribute requests between multiple servers

•Not suitable for all applications

Comparing Hardware and Software Load Balancing

Hardware load balancing:

• Uses a device to provide the virtual IP

• Requires multiple devices to guarantee fault tolerance

Software load balancing:

• All cluster nodes provide the virtual IP

• There is no single point of failure

What Is Failover Clustering?

Passive NodePassive Node

Active NodeActive Node

Active NodeActive Node

SharedStorageSharedStorage

Private NetworkPrivate

Network

Public NetworkPublic

Network

Lesson 2: Windows Network Load Balancing

• What Is Windows Network Load Balancing?

• Requirements for Windows Network Load Balancing

• How Windows Network Load Balancing Works

• Data Synchronization between NLB Nodes

What Is Windows Network Load Balancing?

Windows NLB:

• Is a fully distributed software solution for load balancing

• Is included with all versions of Windows Server® 2008

Session Broker:

• For Terminal Services

• Distributes session requests to the least loaded server

• Provides scalability and availability

• Included in all version of Windows Server 2008

Requirements for Windows Network Load Balancing

Requirements:

• At least one network adapter for load balancing

• Only TCP/IP on the NLB adapter

• All NLB nodes on the same subnet

How Windows Network Load Balancing Works

Unicast mode:

• A unique NLB MAC address is assigned to NLB adapter in all nodes

• The original MAC address of the NLB adapter cannot be used

• Packets are received by all NLB nodes

• Only the appropriate NLB node responds

• Outgoing MAC is unique for each node to avoid switch problems

Multicast mode:

• A multicast MAC address is assigned to the NLB adapter in all nodes

• The original MAC address of the NLB adapter can still be used

• Removes the need for two network adapters

• Only the appropriate NLB node responds

Data Synchronization between NLB Nodes

All NLB nodes must have the same data to make sure that all nodes respond identically to requestsAll NLB nodes must have the same data to make sure that all nodes respond identically to requests

Data access can be provided by:

•Synchronizing content between servers

•Storing data in a common location

NLB ClusterNLB Cluster

Database ServerDatabase Server

Lesson 3: Configuring Windows Network Load Balancing

• What Are the Cluster Parameters?

• What Are Port Rules?

• What Is the Filtering Mode?

• What Is Affinity?

• What Are the Host Parameters?

• Demonstration: Creating an NLB Cluster

What Are the Cluster Parameters?

Cluster parameter Description

IP address Virtual IP address of the NLB cluster

Network address MAC address of the NLB cluster

Cluster operation mode Specified whether unicast or multicast operation is used

Cluster parameters include the following:

What Are Port Rules?

Port rules specify how requests to a certain IP address and port range are handledPort rules specify how requests to a certain IP address and port range are handled

Port rules define:

•Filtering mode

•Affinity

•Load weight

•Handling priority

What Is the Filtering Mode?

Filtering mode Description

Multiple hosts All NLB nodes respond based on the weight assigned to each node

Single host Only the NLB node with the highest priority responds

Disable this port range All traffic for this port range is blocked

What Is Affinity?

Affinity Description

None Each client request could be distributed to any node

Single All requests from a single client are distributed to a single node

Network All requests from a single class C sized network are distributed to a single node

Affinity controls how requests from a client are distributed among multiple nodes in an NLB clusterAffinity controls how requests from a client are distributed among multiple nodes in an NLB cluster

What Are the Host Parameters?

Host parameter Description

Initial host state Specifies whether the host automatically joins the NLB cluster when started

Dedicated IP address IP address that is used on the host for cluster management

Priority Determines in which order the host is when a port rule does not apply

Host parameters include the following:

Demonstration: Creating an NLB Cluster

In this demonstration, you will see how to configure an NLB cluster

Lab: Implementing Network Load Balancing

• Exercise 1: Preparing Web Servers for NLB

• Exercise 2: Creating an NLB Cluster for Failover

• Exercise 3: Configuring an NLB Cluster for Load Balancing

Logon information

Virtual machine NYC-DC1, NYC-WEB, NYC-SVR1

User name Administrator

Password Pa$$w0rd

Estimated time: 60 minutes

Lab Review

• When an NLB cluster is configured with single host filtering mode, how is the responding node determined?

• When an NLB cluster is configured with multihost filtering mode, how is the responding node determined?

Module Review and Takeaways

• Review Questions

• Real-world Issues and Scenarios

• Best Practices

• Tools