SAP Basis Tech Supports

Symptom
You want to use SAP Web Dispatcher in order to access Web Dynpro for ABAP or BSP applications from the portal. The Web Dispatcher is therefore before the SAP Web AS ABAP.
If Web Dynpro applications are executed in the portal using the Web Dispatcher, errors occur because the Web Dispatcher has sent related HTTP requests to different application servers.
This occurs because the Web Dispatcher does not support the external session ID (ESID) of the portal. As a result, the Web Dispatcher passes on requests that are intended for a certain HTTP session to another application server and not to the server where the session and the respective user context are located.
This note describes the support of the external session ID (ESID) of the portal in the SAP Web Dispatcher.
Reason and Prerequisites
You want to use Web Dispatcher to access Web Dynpro for ABAP from the portal.
Solution
For the support of ESIDs in Web Dispatcher, one of the following SAP Web Dispatcher versions is required:
6.40 patch level 937.00 patch level 26For higher releases, no particular patch level is required.
However, at least one of the above-mentioned versions of the sapwebdisp(.exe) executable is required.
We recommend that you additionally import the above-mentioned versions of the icmon(.exe) executable and the admin directory that are used for the monitoring the Web Dispatcher.
The installation of the Web dispatcher is described in the online help.
In Releases 6.40 and 7.00, the following parameter has to be specified to activate the ESID support:
wdisp/HTTP/esid_support=1
The following patch level changes the default to 1:
6.40: 1867.00: 115
In higher releases, ESID support is the default setting. If you do not require this, you can deactivate it by setting
wdisp/HTTP/esid_support=0

You can set the following parameters for advanced configuration of the ESID support. They are not usually required.
wdisp/HTTP/max_esid_entries (default value 50000)
Describes the maximum number of entries in the ESID table.wdisp/HTTP/max_logon_groups (default value 32)
Describes the maximum number of logon groups that can be addressed by the Web dispatcher.wdisp/HTTP/context_timeout (default value 3600)
Describes the timeout for entries in the ESID table.
The wdisp/HTTP/max_esid_entries and wdisp/HTTP/context_timeout parameters correspond exactly with the wdisp/HTTPS/max_client_ip_entries and wdisp/HTTPS/context_timeout parameters that are used for dispatching SSL end-to-end requests . When you set the parameters, refer to the documentation for the corresponding SSL parameter (see the online help).