Memory Requirement of the SAP Web Dispatcher 

The SAP Web dispatcher must reserve as much memory as possible to store large tables.

The server tables contain the configuration values from the three files, info.icr, groups.icr, and urlprefix.icr (or fetched from the application servers).

The following formula estimates roughly how much memory is required:

Memory requirement  = (S × N_S + G × N_G + U × N_U) × 2 Bytes

The letters have the following meaning:

Variable	Parameter Value	Default value
S	wdisp/max_servers	128
NS	wdisp/max_server_name_len	64
G	wdisp/max_server_groups	128
NG	wdisp/max_server_group_name_len	20
U	wdisp/max_url_map_entries	300
NU	wdisp/max_url_map_path_len	256

For the default settings this comes to 87552 bytes, which is negligible.

MPI Parameters

The MPI memory is a pure communication memory. This means the Web dispatcher reads the data from a partner into this memory and then forwards this data to another partner. Once the data has been forwarded the memory is free again. The whole MPI memory (mpi/total_size_MB) is split into blocks of a fixed size of the value of mpi/buffer_size. The standard value of mpi/total_size_MB is 80 (megabytes). The standard value of mpi/buffer_size is 65536 (bytes).

IP Mapping Tables for Stateful SSL Connections

The SSL client IP table is needed for end-to-end SSL and contains the mapping of client IP to the application server:

The section Profile Parameters of the SAP Web Dispatcher contains further information about the parameter wdisp/HTTPS/max_client_ip_entries, and a table containing examples of the memory required for certain settings.