Extreme Networks Px Series manual Load Balancing Modes, Layer 4 Load Balancing

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Load Balancing Modes

In this document, the Internet users are referred to as clients, because they are clients of the application switch. The website, which is actually an address inside the application switch, is also called a virtual IP address, or VIP. Because the Px series application switch uses the unique combination of IP address and source port, the VIP is referred to as a virtual service.

Load Balancing Modes

The Px series application switch can perform packet redirection for load balancing in two different ways:

Layer 4 load balancing

Layer 7 load balancing

Layer 4 Load Balancing

In layer 4 mode, the application switch decides which server should receive a given user request using server selection policies. It selects a server without looking at the content of the request. The following server selection policies are supported by the Px series application switch:

Round robin

Weighted round robin

Least connections

Weighted least connections

For more information on policies, see Chapter 6.

The application switch can balance almost any traffic using network address translation (NAT) at layer 4. The application switch rewrites the destination IP address of the request to point to the real server selected to handle the request, and sets the source IP address of the request to point to one of the internal IP addresses of the Px series application switch. When the server responds to the request, the application switch rewrites the response so that it appears to originate from its VIP address, and forwards the response to the client.

Figure 1-2 illustrates a single client-server transaction using layer 4.

Px Series Application Switch Installation and Configuration Guide

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Contents Published April Part number 100101-00 Rev Page Contents Installing the PxM Application Switch Module Configuring Servers and Services Index Index of Commands Introduction PrefaceText Conventions ConventionsIcon Alerts you to Convention DescriptionRelated Publications Preface Purpose of Server Load Balancing Server Load Balancing Concepts1Conceptual view of server load balancing TermsLayer 4 Load Balancing Load Balancing Modes2Single client-server transaction using layer Layer 7 Load Balancing and Content Analysis3Establishing a layer 7 request Port Rewrite Getting Started on Load Balancing ConfigurationGetting Started on Load Balancing Configuration Page Overview of the SummitPx1 Application Switch Installing the SummitPx1 Application SwitchSummitPx1 Front View Color Indicates 1Px series application switch LEDsSignal Description SummitPx1 Application Switch Rear View2DB-9 Adapter Pinouts To DB-9Determining the Location Installing the SummitPx1 Application SwitchRack Mounting Free-Standing Powering On the SummitPx1Setting Up Console Communication Configuring Switch IP Parameters Configuring the 10/100 Ethernet Management Port Installing I/O Modules Installing the PxM Application Switch ModuleRemoving I/O Modules Removing I/O Modules Page Managing the Switch Abbreviated Syntax and Command Completion Using the Command-Line InterfaceSyntax Symbols 1Command Syntax SymbolsLine-Editing Keys Symbol DescriptionSpecifying Text Values 2Line-Editing KeysCommand History Configuring Management AccessPrompt Text Changing the Default Passwords Modifying Accounts Creating AccountsManaging the PxM Command DescriptionConfiguring VLANs 4SNMP Configuration Settings Configuring SnmpSetting Description System ContactSettingDescription Configuring DNS Client Services5DNS Client Configuration Commands Using Secure Shell 2 SSH2Config ssh2 key Enabling SSH2 for Inbound Switch AccessUsing SCP2 from an External SSH2 Client SSH2 Client Functions on the Switch Showing CPU Load UtilitiesChecking Basic Connectivity Logging Starting the GlobalPx Content Director Agent Configuring a Startup Banner MessageInternet DNS server Example ConfigurationFollowing commands configure all system-related facilities Page Configuring Real Servers Configuring Servers and ServicesConfiguring Server Groups Configuring Virtual Services Layer 4 Port-based Load Balancing Layer 7 Virtual ServicesConfiguring Traffic Tagging 1Tag Specifications Configuration ExampleTag Specification Description Tag Range Configuration Example Page Scheduling Policies Choosing Policies, Persistence Modes, and NAT1Scheduling Policies Persistence ModesSpecifier Policy Description UDP Flow Persistence Client IP Persistence Mode1Client IP persistence mode Cookie Persistence Modes Configuring Client IP Stickiness2Self-identifying cookie persistence mode Persistence Modes Hashed Cookie Persistence Session Learned Cookie Persistence Mode 4Learned cookie persistence mode Configuring Cookie Stickiness SSL Session Identifier Persistence NAT Modes Full-NAT ModeConfiguring Full-NAT Mode and Proxy IP Addresses Server-only Half-NAT ModeConfiguring Half-NAT Mode Config source-flow name next-hop gateway-mode ip Real Syslog server SummitPx1 Configuration Example Page Domain and URL Switching URL Switching1Typical switching scenario Domain Switching2Domain switching example URL Switching Configuring URL Switching3Simple URL switching example 4More Complicated URL switching example 5Hierarchical approach to pattern rules 1Wildcard Combinations Creating Domain and URL Switching RulesWildcard Example Definition Modifying Existing URL Rules and Domains Application Servers Management net Configuration Example Page Using Vrrp with the SummitPx1 Configuring RedundancyGive backup systems lower priorities Adding and Configuring VRRPsUsing Vrrp in Existing Redundant Networks Vrrp Automatic Synchronization 1Application switch using multiple VLANsFollowing commands can be passed from master to backup Using Esrp with the PxM Configuring Redundancy for the PxMFor SW2 Configuring the PxM for Multiple VLANsConfiguring a Default Gateway Overview Health ChecksServer Startup Pacing Health Checking Procedure Timers and Counters Configuring Health ChecksTypes of Health Checks You can disable health checks for a server group Page 1Statistics Display Commands Monitoring the SwitchShowing Traffic Statistics Displays packet-level counters for 2Configuration Display Commands Showing Configuration DetailsConfiguration Displays SummitPx128 # show server details Status DisplaysColumn Description Show health Information5Management and Troubleshooting Commands Managing and Troubleshooting OperationCommandDescription Esrp IndexHttp GET AUX Page Index of Commands