WebSphere Virtual Enterprise, Version 6.1.1
             Operating Systems: AIX, HP-UX, Linux, Solaris, Windows, z/OS


Defining generic server clusters for remote ODR cells

In order for the on demand router (ODR) to route to other cells, generic server clusters must be defined to represent those cells. The purpose of defining generic server clusters is to allow each ODR to recognize the other ODRs that are in remote cells.

About this task

Defining the generic server clusters provides a way for the ODRs in one cell to send traffic to the ODRs in the other cell. There are several reasons why this is important. First, if all the application servers in a cell are unavailable, the ODRs in that cell need to send requests somewhere. They will send the requests to the GSC (representing the ODRs in the other cell). The ODRs in the other cell will then route the requests to application servers in their own cell, ensuring that the requests are handled successfully. Second, if a request which has session data associated with an application server in Cell1 is mistakenly sent to an ODR in Cell2, the ODR in Cell2 needs to be able to forward the request to an ODR in Cell1, as only the ODRs in Cell1 can send the request to the appropriate application server (The ODRs in Cell2 cannot send requests directly to an application server in Cell1). The GSC will again be used to allow the ODR in Cell2 to forward the request to an ODR in Cell1 which will then handle the request.

Procedure

  1. Configure trusted proxies. All ODRs need to include as trusted proxies all other ODRS (including those in remote cells), and all WebServer/IHS Servers that will send traffic to this ODR. Follow the WebSphere Network Deployment instructions in the Proxy server settings topic for most of the instructions to configure ODRs. See Configuring ODRs for WebSphere® Virtual Enterprise specific fields.
  2. From the administrative console, create a new generic server cluster. Select Servers > Generic Server Clusters > New.
  3. Provide a name, select a protocol, and click OK.
  4. Click the newly-created generic server cluster, and click Ports.
  5. Click New, and specify the host name and port number of the ODR as the member of the generic server cluster.

    When defining GSC members in which more than one GSC member (including members in different GSCs) resides on the same node (i.e. has the same host name), you must define the server=<uniqueServerName> custom property on the GSC member definition in order to ensure uniqueness of the GSC member names in the ODC. Without this custom property, the GSC member name will be based on the host name configured, which will not be unique for two members on the same node and will result in improper routing. With this property, the GSC member name will be the value provided in the custom property.

    The ODR normally calculates the cloneID for a server from the host name and the non-SSL ODR port. This same mechanism is used to calculate GSC member cloneIDs. Thus, when an ODR in one cell is represented by a GSC member in another cell, the cloneIDs automatically match. However, an override mechanism is provided which allows the cloneID to be specified manually. To do so, define a custom GSC member property named ODRCloneId with the value set to the desired cloneID. This value must match the calculated cloneID of the ODR in the remote cell.

  6. Repeat step 5 for each ODR in the cell that the generic server cluster represents.
  7. Repeat steps 1 through 5 for each cell in your topology.
  8. Click Save to save your configuration changes.

Results

Configuring the GSC representations of the ODRs in the remote cell allows traffic which was misrouted to one cell to be forwarded to the correct cell, maintaining cell affinity. It does not enable failover, meaning that if an ODR has no available servers in its cell, it will be unable to service the request. To enable the ODR to send the request to an application server in a remote cell, in the case that no local servers are available, see Configuring the on demand router for multi-cluster failover and load balancing routing .




Related information
Creating and configuring ODRs
Configuring ODRs
Cell affinity function
Enabling cell affinity
Configuring cell affinity in a multi-tiered environment
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Last updated: Oct 30, 2009 1:32:42 PM EDT
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