Does the EdgeADC support Persistence based load-balancing?

PostedMarch 28, 2024

UpdatedMarch 28, 2024

Persistence, also known as sticky sessions, in the context of load balancers, refers to a method used to maintain a consistent user session on the same server during multiple requests. When a user first connects to a web application via a load balancer, persistence ensures that all subsequent requests from that user during the session are directed to the same backend server. This is crucial for applications where the session state is stored locally on the server, such as in shopping carts or user login sessions. Persistence is achieved through various mechanisms, such as IP hashing, where the user’s IP address determines the server, or cookie insertion, where the load balancer places a special cookie in the user’s browser to track the server assignment. This approach enhances the user experience by ensuring continuity and consistency in their interaction with the application.

The EdgeADC supports several Persistence based load-balancing policies.

Option	Description
Persistent Cookie	Layer 7 Session Affinity/Persistence The IP list-based load balancing mode is used for each first request. The ADC inserts a cookie into the headers of the first HTTP response. After that, the ADC uses the client cookie to route traffic to the same back-end server. This cookie is used for persistence when the client must go to the same back-end server each time. The cookie will expire after 2 hours, and the connection will be load balanced according to an IP List Based algorithm. This expiry time is configurable using a jetPACK.
IP Bound	Layer 3 Session Affinity/Persistence Cookie. In this mode, the client’s IP address forms the basis to select which Real Server will receive the request. This action provides persistence. HTTP and Layer 4 protocols can use this mode. This method is helpful for internal networks where the network topology is known, and you can be confident that there are no “super proxies” upstream. With Layer 4 and proxies, all the requests can look as if they are coming from one client, and as such, the load would not be even. With HTTP, the header (X-Forwarder—For) information is used when present to cope with proxies.
IP List Based	The connection to the Real Server initiates using “Least connections” then, session affinity is achieved based on the client’s IP address. A list is maintained for 2 hours by default, but this can be changed using a jetPACK.
Shared IP List Based	This service type is only available when the Connectivity Mode is set to Direct Server Return. It has been primarily added for support with VMware load balancing.
Persistent Cookie	Layer 7 Session Affinity/Persistence The IP list-based load balancing mode is used for each first request. The ADC inserts a cookie into the headers of the first HTTP response. After that, the ADC uses the client cookie to route traffic to the same back-end server. This cookie is used for persistence when the client must go to the same back-end server each time. The cookie will expire after 2 hours, and the connection will be load balanced according to an IP List Based algorithm. This expiry time is configurable using a jetPACK.
Classic ASP Session Cookie	Active Server Pages (ASP) is a Microsoft server-side technology. With this option selected, the ADC will maintain session persistence to the same server if an ASP cookie is detected and found in its known cookies list. On detection of a new ASP cookie, it will be load balanced using the Least Connections algorithm.
ASP.NET Session Cookie	This mode applies to ASP.net. With this mode selected, the ADC will maintain session persistence to the same server if an ASP.NET cookie is detected and found in its list of known cookies. On detection of a new ASP cookie, it will be load balanced using the Least Connections algorithm.
JSP Session Cookie	Java Server Pages (JSP) is an Oracle server-side technology. With this mode selected, the ADC will maintain session persistence to the same server if a JSP cookie is detected and found in its known cookies list. On detection of a new JSP cookie, it will be load balanced using the Least Connections algorithm.
JAX-WS Session Cookie	Java web services (JAX-WS) is an Oracle server-side technology. With this mode selected, the ADC will maintain session persistence to the same server if a JAX-WS cookie is detected and found in its list of known cookies. On detection of a new JAX-WS cookie, it will load balanced using the Least Connections algorithm.
PHP Session Cookie	Personal Home Page (PHP) is an open-source server-side technology. With this mode selected, the ADC will maintain session persistence to the same server when a PHP cookie is detected.
RDP Cookie Persistence	This load balancing method uses the Microsoft-created RDP Cookie based on username/domain to provide persistence to a server. The advantage of this method means maintaining a connection to a server is possible even if the IP address of the client changes.