Configuration rules

The following rules will provide help for the proper configuration BCOM and the underlying SNA Stack on MVS, NSK Guardian and Windows NT.

• The RU size should be set to the largest possible value;
• The MAXBLK parameter should be set to the maximum possible value, but not larger than the RU size. The MAXBLK parameter should also account for GDS information (see tables later for precise values);
• Use the largest value possible for the PIU, depending on the underlying medium, to decrease or eliminate segmentation. This value will vary depending on the medium (SDLC, Token-Ring, and Ethernet).

The sample configuration
The following diagram shows a sample configuration that was used to illustrate the relationship between the various size parameters:

The following nodes are defined in the configuration:

• The MVS system runs MVS/ESA Version 5.2 and VTAM Version 4.3. There is one Token-Ring connection (16Mbps ring) through an emulated 3172 (the hardware is a PC Server/390);
• The NSK Guardian system runs Guardian D43. There is one Token-Ring connection (16Mbps ring) through a 3616 controller. The hardware is a K1000-2;
• The AS/400 runs OS/400 Version 3.2. There is one Token-Ring connection (4Mbps ring);
• The Windows NT %Q1W location runs under Windows NT Workstation 4.0SP3 and connects to SNA Server through the TCP/IP protocol over Ethernet 10BaseT. The hardware is a Pentium-200 with 64MB of memory;
• The SNA Server (COYOTE) runs under Windows NT Server 4.0SP3 and SNA Server 3.0SP2. It connects to a 16Mbps Token-Ring (for MVS and NSK Guardian connections), a 4Mbps Token-Ring (for the AS/400) and an Ethernet 10BaseT (for BCOM for Windows NT client);

All the values in the following tables are based on this sample configuration.