Paths
When you know the physical structure of your network, remember to define the paths between the different nodes with PATH definition statements.
Figure 1 illustrates the meaning of the PATH statement.
Code a PATH statement for each subarea (host or NCP) with which the VTAM® program needs to communicate. Code a PATH statement for every subarea except your own.
The statement first defines the destination subarea. You can use the same statement for more than one subarea. Next, the statement must define the explicit routes and virtual routes (ERs and VRs) that make up that path.
An ER defines the physical elements that connect two subareas. A VR is the logical connection between two subareas. A VR uses the physical route defined by an ER. Associate each ER with a VR. ERs have the additional characteristic of a transmission priority.
The VTAM program needs both ERs and VRs to set up a session. The VTAM program begins with a VR and then uses the PATH table to determine which ER to which the VR maps. A class-of-service table tells the VTAM program which VR to use. In Figure 1, if the class of service says that VR1 is to be used, then the VTAM program uses the PATH statement and map that statement into ER0.
- Change the DESTSA operands to match the subareas in your network.
- Change the ER and the VR operands to fit your own routing scheme.
- Add the VRPWSxy operands to fit your network or use the default values. The VRPWSxy operand defines the minimum and maximum window size for the specified virtual route and transmission priority.
You can use the Network and Design Analysis (NETDA) program to create your path tables.
The following defines the paths for A01MPU in NETA. The sample path tables A02PATH (CNMS0025) and A99PATH (CNMS0036) for A02MPU and A99MPU in NETA are also included on the distribution media. The path definition for B01MPU in NETB is B01PATH (CNMS0105).
