Avaya P330 User Manual

Avaya P330

Load Balancing

Manager

User Guide

March 2002

Avaya P330 Load Balancing Manager User Guide

The products, specifications, and other technical information regarding the products contained in this document are subject to change without notice. All information in this document is believed to be accurate and reliable, but is presented without warranty of any kind, express or implied, and users must take full responsibility for their application of any products specified in this document. Avaya disclaims responsibility for errors which may appear in this document, and it reserves the right, in its sole discretion and without notice, to make substitutions and modifications in the products and practices described in this document.

Avaya™, Cajun™, CajunRules!™, CajunDocs™, OpenTrunk™, P550™, LANstack™, and Avaya MultiService Network Manager are registered trademarks and trademarks of Avaya Inc.

ALL OTHER TRADEMARKS MENTIONED IN THIS DOCUMENT ARE PROPERTY OF THEIR RESPECTIVE OWNERS.

Release 2.003

Table of Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vi

The Purpose of This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Who Should Use This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Organization of This Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Chapter 1 — Overview of Load Balancing. . . . . . . . . . . . . . . . . . . . . . 1

What is Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Load Balancing Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

Firewall Load Balancing (FWLB) . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

FWLB Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Benefits of FWLB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Transparent Routing Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Non-Transparent Routing Firewalls . . . . . . . . . . . . . . . . . . . . . .6

Bridging Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Server Load Balancing (SLB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

SLB Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Benefits of SLB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Server Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Direct Server Return (Triangulation) . . . . . . . . . . . . . . . . . . . .10

Application Redirection (AR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

AR Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Benefits of AR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Cache Redirection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Combination of Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Load Balancing Metrics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

Round Robin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Hash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

MinMiss Hash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Weighted Real Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Health Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Persistency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Additional Persistency Schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

Chapter 2 — Getting Started with Avaya P330 Load Balancing

Manager. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Starting Avaya Load Balancing Manager . . . . . . . . . . . . . . . . . . . . .18

The User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

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Logical View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Logical Tree Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Table Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

RSG Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

RS Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Form Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Physical View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Physical Tree Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Virtual Form Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Saving Configuration Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Applied Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Committed Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Searching for Load Balancing Components . . . . . . . . . . . . . . . . . . .26

Chapter 3 — Configuring Firewall Load Balancing. . . . . . . . . . . . . . 27

Firewall Load Balancing Configuration Overview . . . . . . . . . . . . . .28

Defining a Firewall Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Editing the Routing Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Defining RSGs and RSs for FWLB . . . . . . . . . . . . . . . . . . . . . . . . . .31

Editing the Properties Sheets for FWLB . . . . . . . . . . . . . . . . . . . . . .31

Module Properties Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Routing Firewall Properties Sheet . . . . . . . . . . . . . . . . . . . . . . .33

Bridging Firewall Properties Sheet . . . . . . . . . . . . . . . . . . . . . .34

Launching Another Avaya Device Manager . . . . . . . . . . . . . . . . . .34

Chapter 4 — Configuring Server Load Balancing . . . . . . . . . . . . . . . 36

Server Load Balancing Configuration Overview . . . . . . . . . . . . . . .37

Defining a Virtual Server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Defining a Virtual Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39

Proxy IP Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Adding PIP Banks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Modifying PIP Banks . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Deleting PIP Banks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

Health Check Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Adding Health Check Methods . . . . . . . . . . . . . . . . . . . . . .44

Modifying Health Check Methods . . . . . . . . . . . . . . . . . . .44

Deleting Health Check Methods . . . . . . . . . . . . . . . . . . . . .45

Health Check Method Properties . . . . . . . . . . . . . . . . . . . .45

Defining RSGs and RSs for SLB . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Editing the Properties Sheets for SLB . . . . . . . . . . . . . . . . . . . . . . . .47

Module Properties Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Virtual Server Properties Sheet . . . . . . . . . . . . . . . . . . . . . . . . .49

SLB Virtual Service Properties Sheet . . . . . . . . . . . . . . . . . . . . .49

Chapter 5 — Configuring Application Redirection . . . . . . . . . . . . . . 51

Application Redirection Configuration Overview . . . . . . . . . . . . . .52

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VLAN Area Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Mapping VLAN Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

Defining a Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55

Defining RSGs and RSs for Application Redirection . . . . . . . . . . . . .56

Defining a Rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Using Address Wildcards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

Editing the Properties Sheets for AR . . . . . . . . . . . . . . . . . . . . . . . .59

Module Properties Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60

AR Virtual Service Properties Sheet . . . . . . . . . . . . . . . . . . . . .61

Chapter 6 — Real Server Groups and Real Servers. . . . . . . . . . . . . . 62

Real Server Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Real Server Group Backup . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Defining an RSG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Defining a Connected RSG . . . . . . . . . . . . . . . . . . . . . . . . .64

Defining an Unconnected RSG . . . . . . . . . . . . . . . . . . . . . .65

Deleting an RSG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65

Real Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Real Server Backup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

Defining an RS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

Defining an RS for an RSG - Logical View . . . . . . . . . . . . .67

Defining an RS for an RSG - Physical View . . . . . . . . . . . .68

Defining an Unconnected RS . . . . . . . . . . . . . . . . . . . . . . .68

Deleting an RS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Editing the RSG and RS Properties Sheets . . . . . . . . . . . . . . . . . . . .70

Real Server Group Properties Sheet . . . . . . . . . . . . . . . . . . . . .70

Real Server Properties Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Chapter 7 — Application Editor Tool . . . . . . . . . . . . . . . . . . . . . . . . . 72

Application Editor Tool Overview . . . . . . . . . . . . . . . . . . . . . . . . . .72

Using the Application Editor Tool . . . . . . . . . . . . . . . . . . . . . . . . . .73

Adding Application Protocols . . . . . . . . . . . . . . . . . . . . . . . . . .74

Modifying an Application Protocol . . . . . . . . . . . . . . . . . . . . . .74

Deleting an Application Protocol . . . . . . . . . . . . . . . . . . . . . . . .74

Applying Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Appendix A — Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

File Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

Edit Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

Action Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76

Tools Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Help Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Appendix B — Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Avaya P330 Load Balancing Manager User Guide v

Preface

Welcome to Avaya P330 Load Balancing Manager. This chapter provides an introduction to this guide. It includes the following sections:

• - A description of the goals of the guide.

• - The intended audience of this guide.

• Organization of This Guide - A brief description of the subjects contained in the various sections of this guide.

The Purpose of This Guide

This guide contains the information needed to use Avaya P330 Load Balancing Manager efficiently and effectively.

Who Should Use This Guide

This guide is intended for use by network managers familiar with network management and its fundamental concepts.

Organization of This Guide

This guide is structured to reflect the following conceptual divisions:

• Preface - This section describes the guide’s purpose, intended audience, and organization.

• Overview of Load Balancing - This section provides an overview of the terms and concepts used in load balancing.

• Getting Started with Avaya Load Balancing Manager - This section provides an overview of the user interface and instructions on how to start and use Avaya P330 Load Balancing Manager.

• Configuring Firewall Load Balancing - This section describes how to configure Avaya P330 Load Balancing Manager to perform Firewall Load Balancing.

Avaya P330 Load Balancing Manager User Guide vi

Preface

• Configuring Server Load Balancing - This section describes how to configure Avaya P330 Load Balancing Manager to perform Server Load Balancing.

• Configuring Application Redirection - This section describes how to configure Avaya P330 Load Balancing Manager to perform Application Redirection.

• Real Server Groups and Real Servers - This section describes how to configure Real Server Groups and Real Servers for the various load balancing applications.

• Application Editor Tool - This section provides instructions on how to use the Application Editor Tool and how to customize application protocols.

• Menus - The full structure of the menus in Avaya P330 Load Balancing Manager.

• Error Messages - A full explanation of the error messages that appear in Avaya P330 Load Balancing Manager.

Avaya P330 Load Balancing Manager User Guide vii

Overview of Load Balancing

This section describes load balancing and includes the following topics:

• What is Load Balancing - A general overview of load balancing.

• Load Balancing Elements - A description of the conceptual load balancing elements.

• Firewall Load Balancing (FWLB) - An overview of Firewall Load Balancing, including descriptions and configuration examples for routing and bridging firewalls.

• Server Load Balancing (SLB) - An overview of Server Load Balancing, including descriptions and examples of SLB with Full and Half Network Address Translation (NAT).

• Application Redirection (AR) - An overview and description of Application Redirection, including a description of Cache Redirection.

• Combination of Applications - A description of how to combine more than one load balancing application.

• Load Balancing Metrics - A description of the various metrics used to direct traffic to different Real Servers.

• Health Check - A description of how health checks are performed by the load balancer.

• Persistency - A description of session and client persistency and how they are sustained.

• Additional Persistency Schemes - A description of backup Real Servers and backup Real Server Groups.

Avaya P330 Load Balancing Manager User Guide 1

What is Load Balancing

Load balancing technology allows system administrators to replace single firewalls and servers with multiple firewall and server farms, achieving the following goals:

• Improving resilience by removing single points of failure.

• Improving performance by utilizing multiple units instead of a single one.

This improves the scalability and maintainability of the firewalls and servers in the network.

The load balancer also serves as a ‘smart redirector’, allowing traffic redirection, commonly known as Application Redirection. This allows for:

• Invisibly intercepting web traffic and forwarding it to deployed web caches.

• Redirecting specific application traffic to content inspection engines.

• Policy based routing, providing routing based on application or data source.

There are several different load balancing applications:

• Firewall Load Balancing (refer to “Firewall Load Balancing (FWLB)” on page 4).

• Server Load Balancing (refer to “Server Load Balancing (SLB)” on page 8).

• Application Redirection (refer to “Application Redirection (AR)” on page 10).

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Chapter 1

Load Balancing Elements

There are several abstract load balancing elements:

• Real Server (RS) - An RS is a physical server that is associated with a Real IP address. One or more RSs may belong to an RSG.

• Real Server Group (RSG) - An RSG is a logical grouping of Real Servers used for load balancing. For example, for SLB, the load balancer distributes packets to Real Servers belonging to a specific RSG.

• Virtual Service - Virtual Services are abstract links to the RSGs provided by a Virtual Server. For example, load-balanced forwarding of HTTP or FTP packets is a Virtual Service.

• Virtual Server - A Virtual Server represents the server to the outside world. It is associated with a Virtual IP address and provides Virtual Services. For example, a load balancer that intercepts traffic from the WAN acts as a Virtual Server.

Traffic from the WAN is directed to the V irtual Server. The Virtual Server provides Virtual Services when transferring packets to the RSG, which is comprised of RSs. The following figure illustrates the conceptual load balancing model.

Figure 1-1. The Conceptual Load Balancing Model

Virtual

Server

Virtual

Service

RSG RSG RSG

Real

Server

Virtual

Service

Real

Server

Virtual

Server

Virtual

Service

Real

Server

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Firewall Load Balancing (FWLB)

This section provides information about Firewall Load Balancing, including a general overview and detailed information about routing and bridging firewalls.

FWLB Overview

Firewall Load Balancing intercepts all traffic between the LAN and the WAN, and dynamically distributes the load among the available firewalls, based on FWLB configuration. Using FWLB, all of the firewalls are utilized concurrently, providing overall improved firewall performance, scalability and availability.

The firewalls are the Real Servers, and the group of firewalls is the Real Server Group. The firewall group is associated with a Virtual Service, which is a routing or bridging firewall.

The load balancer:

• Balances traffic across two or more firewalls (up to 1024) in your network, allowing the firewalls to work in parallel.

• Maintains state information about the traffic flowing through it and ensures that all traffic between specific IP address source and destination pairs flows through the same firewall.

• Performs health checks on all paths through the firewalls. If any path is not operational, the load balancer diverts traffic away from that path, maintaining connectivity across the firewalls.

Often, two load balancers are needed to support FWLB. One device is deployed on the LAN side (internal) of the firewalls and another on the WAN side (external). If a Demilitarized Zone (DMZ) is implemented to allow remote access, a third load balancer must be deployed on the DMZ side of the network. Additional devices can be added to provide redundancy, eliminating any device or path as a single point of failure.

A vaya P330 Load Balancin g Manager supports both routing and bridging firewalls. Routing firewalls may be transparent or non-transparent.

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Chapter 1

Benefits of FWLB

FWLB allows you to:

• Maximize firewall productivity.

• Scale firewall performance.

• Eliminate the firewall as a single point of failure.

Transparent Routing Firewalls

For transparent FWLB, the load balancer receives a packet, makes a load balancing decision, and forwards the packet to a firewall. The firewall does not perform NAT on the packets; the source and destination IP addresses are not changed.

Two load balancers are required for transparent FWLB, one on each side of the firewalls. One device intercepts traffic between the WAN and the firewall, and the second device intercepts traffic between the LAN and the firewall.

Transparent routing firewalls act as a “next hop” device from the perspective of the load balancer. After a firewall is selected in a load balancing decision, normal routing to that firewall takes place.

The load balancers ensure that all packets belonging to a session pass through the same firewall in both directions. The devices select a firewall based on a symmetric hash function of the source and destination IP addresses. This ensures that packets traveling between the same source and destination IP addresses traverse the same firewall.

The following figure illustrates transparent FWLB.

Figure 1-2. Transparent Firewall Load Balancing

5 Avaya P330 Load Balancing Manager User Guide

The load balancer enables you to route packets to a DMZ. A DMZ is a portion of the client’s network, apart from the client’s LAN, where remote access is allowed. After creating a DMZ, a third load balancer is installed to route packets to the DMZ. The following figure illustrates transparent FWLB with a DMZ.

Figure 1-3. Transparent FWLB With DMZ

Non-Transparent Routing Firewalls

Non-transparent routing firewalls are firewalls that support dynamic NAT.

For non-transparent FWLB, the load balancer receives an outgoing packet, makes a load balancing decision, and forwards the packet to a firewall. The firewall keeps a bank of IP addresses and replaces the source IP address of the outgoing packet with a unique, arbitrary IP address from the bank. The firewall then forwards the packet to an edge router which routes it to the correct destination on the WAN.

For incoming packets, the unique NA T address is use d as a destination IP address to access the same firewall. The firewall performs reverse NAT by replacing the NAT destination address with the actual destination address (the client IP address), and then forwards the packet to the load balancer, wh ich routes the packet to its destination. No load balancing is performed on incoming packets.

For non-transparent FWLB, only one load balancer is required. The device is positioned on the LAN (internal) side of the firewalls. Since the firewalls perform NAT, a load balancer is not needed between the WAN and the firewalls.

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Chapter 1

In transparent FWLB, persistency is ensured by the load balancer. In non-transparent FWLB, the firewalls ensure persistency through NAT, and there is no need for the load balancer to intervene.

The following figure illustrates non-transparent FWLB.

Bridging Firewalls

Bridging firewalls are firewalls that do not perform forwarding at the IP address layer , but rather appear as transparent bridges. Bridging firewalls are transparent to devices inside and outside of the secured network. The bridging firewalls do not have IP or MAC addresses to which traffic is directed. Therefore, the firewalls must physically appear on the traffic path.

Figure 1-4. Non-Transparent Firewall Load Balancing

For bridging FWLB, the load balancers must be positioned on both sides of the firewalls. Each device load balances between IP address interfaces of the peer device behind the firewall. For this to work, each firewall must reside in a different VLAN and subnet, and the physical ports connected to the firewalls must be on different VLANs as well. In addition, for each VLAN, both load balancers must be in the same subnet.

Each load balancer interface and the firewall connected to it reside in a separate VLAN. This ensures persistency since all the traffic through a particular firewall is contained in the firewall’s VLAN.

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The following figure illustrates bridging FWLB.

Figure 1-5. Bridging Firewall Load Balancing

VLAN 1

LAN

Load Balancer

VLAN 2

Server Load Balancing (SLB)

This section provides information about Server Load Balancing, including a general overview and detailed information about SLB.

SLB Overview

Server Load Balancing intercepts all traffic between clients and servers, and dynamically distributes the load among the available servers, based on the SLB configuration.

In a non-balanced network, each server provides access to specific applications or data. Some of these applications may be in higher demand than others. Servers that provide applications with higher demand are over-utilized while other servers are under-utilized. This causes the network to perform below its optimal level.

Firewall 1

Firewall2

Load Balancer

Access Router

Internet

Load balancing provides a solution by balancing the traffic among several servers which all have access to identical applications and data. This involves intercepting all traffic between clients and load-balanced servers and dynamically distributing the load according to configured schemes (metrics).

The load balancer acts as a Virtual Server to the outside world (the WAN) and has a Virtual IP address.

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Chapter 1

Benefits of SLB

SLB improves network performance by:

• Minimizing server response time.

• Maximizing server availability.

• Increasing server utilization and network bandwidth. This is accomplished by balancing session traffic between the available servers, according to rules established during configuration.

• Increasing reliability. If any server fails, the remaining servers continue to provide services seamlessly.

• Increasing scalability. Server configuration can be performed without disrupting the network.

Server Load Balancing

The server load balancer changes one of the source and destination IP addresses. When a packet arrives from a client to a server, the load balancer changes the destination IP from the Virtual IP address to the Real IP address. When a packet is sent from a server to a client, the load balancer changes the source IP address from the Real IP address to the Virtual IP address.

The following figure illustrates Server Load Balancing:

Figure 1-6. Server Load Balancing

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Direct Server Return (Triangulation)

Direct server return, or triangulation, is an additional implementation of SLB. In standard SLB, the load balancer intercepts traffic between the servers and clients in both directions. In triangulation, load balancing is performed only on traffic from the clients to the server. Traffic from the servers is returned to the client directly through a router without any need for load balancing intervention.

For triangulation, the Real Servers must be specially configured. The Real Servers must also be capable of receiving packets with the V irtual IP address as the destination IP address, and of sending packets with the Virtual IP address as the source IP address. The Virtual IP address should be configured in the Real Servers as a “loopback” IP address, and the router (not the load balancer) should be configured as the servers’ default gateway.

When the load balancer detects that a Real Server supports triangulation and is configured properly, it does not change the destination IP address of the packet. The Virtual IP address is left as the destination IP address, and the packet does not undergo NAT.

Application Redirection (AR)

This section provides information about Application Redirection, including a general overview, and detailed information about Cache Redirection.

AR Overview

With the growing importance of the Internet as a source of information, an organization's LAN may suffer from a degradation of performance due to congestion of the router connecting the network to the Internet.

Since much information retrieved from the Web is either repeatedly requested by a user or requested by multiple users, many organizations implement a local caching mechanism to prevent unnecessary Internet traffic. The local caches must be on the traffic path between the client and the Internet router. As a result, all traffic, even traffic not intended for the cache, passes through the cache.

Load balancing solves this problem by redirecting packets from their original destination to an alternative server based on the Application Redirection configuration. Cache Redirection is the most common implementation of Application Redirection.

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Benefits of AR

By redirecting client requests to a local cache or application server, you can increase the speed at which clients access information and free up valuable network bandwidth.

Application Redirection improves network performance by:

• Providing faster client access to information.

• Increasing effective network bandwidth.

• Filtering traffic.

• Directing only suitable traffic to the local cache.

• Connecting and load balancing multiple caches.

• Performing the redirection process in a way that is transparent to the client.

• Allowing redundant caches to be configured.

Cache Redirection

For Cache Redirection, the load balancer is positioned on the traffic route and redirects traffic from the original destination to an alternative cache server. The redirection process involves the following steps:

1. The load balancer checks whether the packet characteristics

2. The load balancer checks whether the application port is suitable

3. The load balancer routes the packet to the cache server instead of

4. The cache checks if it has the relevant information. If it does, it

comply with one of the defined filter rules. The user configures rules to define which clients or destinations are to be redirected to the cache.

for redirection (i.e., HTTP).

to the original destination on the Internet.

forwards the cached information to the client. If it does not have the information, it retrieves the information from the Internet, saves it to the cache, and then forwards the information to the client.

The load balancer supports transparent caches. A transparent cache is a cache that is capable of accepting packets not a ddressed to its IP add res s. The cache usually uses NAT in its IP address stack, so the higher layers can process packets not addressed to the cache’s IP address.

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The following figure illustrates Cache Redirection.

Figure 1-7. Cache Redirection

In this figure, the sequence of events is as follows:

1. The user issues an HTTP request. The source IP address is the user’s IP address and the destination IP address is the Web server’s IP address.

2. The load balancer routes the packet to the local cache. The packet still has the Web server’s IP address as its destination IP address.

3. If the cache has the required page, the cache returns the page to the load balancer with the destination IP address of the client and the source IP address of the Web server. If the cache does not have the required page, the cache returns the packet to the load balancer, and the load balancer routes the packet to the Web server.

4. On the way back from the Web server, the load balancer routes the packet to the cache.

5. The cache saves the packet and routes it back to the load balancer.

6. The load balancer sends the page to the user.

A client's request for a Web page and the cache's request for a Web page have the same source and destination IP addresses. To distinguish between them, the load balancer uses separate VLANs for clients and the cache. If the request is on the clients' VLAN, the load balancer forwards the request to the cache. If the request is on the cache's VLAN, the load balancer forwards the request to the WAN.

Similarly , the WAN’s return of a Web page and the cache's forwarding of a Web page to a client have the same source and destination IP addresses. To distinguish between them, the load balancer uses separate VLANs for clients and the cache. If the response is on the cache’s VLAN, the load balancer forwards the response to the cache. If the response is on the clients' VLAN, the load balancer forwards the response to the client.

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Combination of Applications

You can enable the P333R-LB to use various applications concurrently. For example, it is possible to configure the same P333R-LB to perform Server Load balancing for an Intranet web-server, Application Redirection for web traffic that is Internet-bound, and Firewall Load Balancing for traffic that is Internet-bound.

In some cases, the same “type” of traffic can be given two different actions by the load balancer . In these situations, it is necessary to tell the load balancer which action to choose. In the example described above, web traffic to the intranet server can be configured to either be directed to the web cache, or bypass the web cache and directly access the Intranet server. The latter configuration will save the web cache resources to deal with Internet-bound traffic.

You can specify the preferred action as one of the following:

• Configure SLB to take precedence over AR.

• AR can take precedence over SLB.

• Configure AR filters to redirect traffic from client/server addresses, using wildcards.

• Configure AR filters to specify which traffic not to redirect (“no-ar” as service) from specific client/server addresses, using wildcards.

Load Balancing Metrics

There are several methods, or metrics, that a load balancer can use to distribute traffic among multiple servers, firewalls or caches. These metrics tell the load balancer which Real Server should receive each session.

Some commonly used metrics are:

• Round Robin

• Hash

• MinMiss Hash

• Weighted Real Servers

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Round Robin

Hash

Using Round Robin, the load balancer issues sessions to each RS in turn. The first RS in the group receives the first session, the second RS receives the next session, and so on. When all the RSs receive a session, the issuing process starts over with the first RS. Round Robin ensures that each RS receives an equal number of sessions.

Using the Hash metric, sessions are distributed to RSs using a predefined mathematical hash function. The hash function is performed on a specified parameter. The source IP address, destination IP address, or both are used as the hash function input.

The load balancer creates a list of all the currently available RSs. The result of the hash function is used to select an RS from the list. Any given parameter always gives the same hash result, providing natural persistency.

If an RS is removed or added to the group, persistency is broken. This occurs since the order of the RSs in the list changes, but the hash still points to the same list entries. The following figure illustrates how a loss of persistency occurs when an RS becomes non-operational:

Figure 1-8. Hash Metric - Loss of Persistency

In the above figure, when Server 2 becomes non-operational, the list of available servers is readjusted, causing a lack of persistency. However, if Server 2 becomes operational again, the list of available servers is restored to its original order, and persistency is recovered.

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MinMiss Hash

MinMiss hash distributes sessions to RSs in the same way as the Hash metric. However, MinMiss hash retains persistency even when an RS is removed from the group. When an RS fails or is removed, the load balancer does not change the position of all the RSs in the list. Instead, it redistributes the remaining RSs to the list entries freed by the failing RS. The following figure illustrates how persistency is retained when an RS becomes non-operational.

Figure 1-9. MinMiss Metric - Persistency Retained

In the above figure, when Server 2 becomes non-operational, the list of available servers is not readjusted. Only the list entries that are now empty are replaced with other available servers. Therefore, persistency is retained for all available servers. However, if Server 2 becomes operational again, the list of available servers is recalculated so that the smallest number of servers is affected. The list is not restored to its original configuration. As a result, persistency is only partially recovered.

Weighted Real Servers

You can assign weights to RSs to enable faster RSs to receive a larger share of sessions. This minimizes overloading and maximizes functionality.

If you assign a weight to an RS, the sessions are distribute d to the RSs in the metric chosen (Round Robin, Hash or MinMiss). However, the weighted RS is assigned a larger share of sessions. For example, if you assign a weight of 20 to one RS and leave the default weight (10)on the second RS, the weighted RS receives 2 sessions for each session directed to the second RS. This is useful for RSs with different bandwidths or processor speeds.

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Health Check

The load balancer constantly checks the RSs to ensure that each RS is accessible and operational. An RS that fails the health check is automatically removed from the load balancer’s internal list of currently available RSs, and traffic is redirected to other available RSs.

There are several types of health check methods that the load balancer can use, including:

For FWLB, checking the firewalls is insufficient. The health checks must be performed on the entities beyond the firewalls as well. In order to ensure that the health check packets traverse the same firewall in both directions, the packet’s source and destination IP addresses should be the IP addresses of the load balancer interfaces on each side of the firewall. For each load balancer, both the local and remote addresses must be configured. In addition, the load balancers on both sides of the firewall must be configured symmetrically.

• ICMP Ping - Each RS is periodically pinged. If no answer is received, the RS is not operational.

• TCP Port Checking - A TCP connection is periodically opened to each RS, checking for successful completion of the connection.

Persistency

For non-transparent FWLB (with NAT), there is only one load balancer. In this case, you must configure an IP address beyond the firewall as the health check address. Like other non-transparent FWLB sessions, the health check session returns through the same firewall according to the NAT address it was given.

Persistency is the maintenance of the connection between the server and the client over multiple sessions. Persistency ensures that all traffic from the client is directed to the same RS.

Persistency is achieved by using naturally persistent load balancing metrics (such as Hash or MinMiss hash) or by forcing persistent load balancing decisions on non-persistent load balancing metrics (such as Round Robin). Persistency is forced by storing the history of the latest decisions in a cache for a limited time, and then sending the packets to the appropriate RS according to the previous load balancing decisions.

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Persistency is achieved by opening a new entry for a server group based on the following:

• New entry on source IP address - All sessions from a specific source are directed to the same RS. This is useful for applications where client information must be retained on the RS between sessions.

• New entry on destination IP address - All sessions to a specific destination are directed to the same RS. This is useful for caching applications to maximize successful cache hits when the information is not duplicated between RSs.

• New entry on source IP and destination IP addresses - All sessions from a given source to a given destination are directed to the same RS. This is useful for Firewall Load Balancing, since it ensures that the two unidirectional flows of a given session are directed through the same firewall.

Additional Persistency Schemes

Using the P333R-LB, you can configure a Real Server to backup one or more primary Real Servers. A backup Real server is not used unless the primary Real Server is down.

You can also configure a Real Server Group (RSG) to backup one or more primary RSGs. A backup RSG can run a different service than the primary RSG while providing backup to all of the primary RSG’ s services. Similar to the Real Server, the backup RSG is not used unless all Real Servers in the RSG are down.

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Getting Started with Avaya P330 Load Balancing Manager

This chapter provides instructions on how to start A vaya Load Balancing Manager and an overview of the user interface. It includes the following topics:

• Starting Avaya Load Balancing Manager - Instructions on how to start Avaya P330 Load Balancing Manager.

• The User Interface - An introduction to Avaya P330 Load Balancing Manager’s user interface.

• Saving Configuration Changes - Instructions for applying and committing changes to the load balancing configuration.

• Searching for Load Balancing Components - Instructions on how to search for RSs and RSGs in Avaya P330 Load Balancing Manager.

Starting Avaya Load Balancing Manager

To start Avaya P330 Load Balancing Manager for the Avaya P330:

1. Click the A list of P333R-LB module IP addresses appears in the Tree View of the Avaya P330 Manager.

* Note: In order that the Load Balancing Manager tab appear, at least

one of the interfaces should be configured on the load balancer. For more information , refer to P333R-LB User Guide or P333R-LB Quick Start.

Load Balancing Manager

tab in the A vaya P330 Manager.

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The User Interface

The user interface consists of the following elements:

• Menu Bar - Menus for accessing Avaya Load Balancing Manager functions (refer to Appendix A, Menus).

• Toolbar - Toolbar buttons for accessing Avaya Load Balancing Manager functions.

• Logical or Physical View - Depending on the tab selected, the application displays one of the two views.

— Logical View - A logical representation of the network

showing Virtual Servers and Services and their associated RSGs and RSs. The Logical View includes a hierarchical Tree Area, Table Area, RSG Area, RS Area, and Form Area. The various areas display information related to the element selected in the Tree Area.

Menu Bar

Toolbar

Tree Area

Status Bar

The following figure shows the Logical View of the user interface, with its various parts labeled.

Figure 2-1. The User Interface - Logical View

Table Area

Form Area

RSG Area

RS Area

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— Physical View - A physical representation of the P333R-LB

devices in the network showing RSs and RSGs. The Physical View includes a Tree Area and a Form Area. The Form Area displays information related to the element selected in the Tree Area.

The following figure shows the Physical View of the user interface, with its various parts labeled.

Figure 2-2. The User Interface - Physical View

Menu Bar

Toolbar

Tree Area

Status Bar

Form Area

• Status Bar - An area at the bottom of the screen that displays the communication status between Avaya Load Balancing Manager and the network.

The toolbar provides shortcuts to Avaya Load Balancing Manager’s main functions. The following table describes the buttons on the toolbar and gives the equivalent menu options.

Table 2-1. Toolbar Buttons

Buttons Description Menu Item

Saves configuration changes to the

File > Commit

device.

Cuts a rule from a table to the

Edit > Cut

application clipboard

Copies a rule from a table to the

Edit > Copy

application clipboard.

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