Radware Alteon, Инструкция по применению

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Document ID: RDWR-ALOS-V2900_AG1302
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Chapter 20 – Persistence
The persistence feature ensures that all connections from a specific client session reach the same
real server, even when Server Load Balancing (SLB) is used.
The following topics are addressed in this chapter:
• Overview of Persistence, page 583 —Gives an overview of persistence and the different types of
persistence methods implemented in Alteon.
• Cookie-Based Persistence, page 585 —Cookie persistence provides a mechanism for inserting a
unique key for each client of a virtual server. This feature is only used in non-Secure Sockets
Layer (SSL) connections. Discusses how persistence is maintained between a client and a real
server using different types of cookies.
• HTTP and HTTPS Persistence Based on Client IP, page 584 —Explains how both HTTP and HTTPS
traffic map to the same server based on client IP.
• Server-Side Multi-Response Cookie Search, page 595 —Explains how to configure Alteon to look
through multiple HTTP responses from the server to achieve cookie-based persistence.
• SSL Session ID-Based Persistence, page 596 —Explains how an application server and a client
communicate over an encrypted HTTP session.
• Windows Terminal Server Load Balancing and Persistence, page 598 —Explains how to configure
load balancing and persistence for Windows Terminal Services.
Overview of Persistence
In a typical SLB environment, traffic comes from various client networks across the Internet to the
virtual server IP address on Alteon. Alteon then load balances this traffic among the available real
servers.
In any authenticated Web-based application, it is necessary to provide a persistent connection
between a client and the content server to which it is connected. Because HTTP does not carry any
state information for these applications, it is important for the browser to be mapped to the same
real server for each HTTP request until the transaction is completed. This ensures that the client
traffic is not load balanced mid-session to a different real server, forcing the user to restart the
entire transaction.
Persistence-based SLB lets you configure the network to redirect requests from a client to the same
real server that initially handled the request. Persistence is an important consideration for
administrators of e-commerce Web sites, where a server may have data associated with a specific
user that is not dynamically shared with other servers at the site.
In Alteon, persistence can be based on:
• Using Source IP Address, page 584
• Using Cookies, page 584
• Using SSL Session ID, page 584