In the TRS (topology and routing services component of VTAM®) common topology trace table, the deletion of NDRECs (node records) and TGRECs (TG records) are recorded.
The TRS common topology trace table is located in extended private storage. At TRS initialization, a 40-K buffer of storage is allocated for the TRS topology trace. When that buffer is filled with trace entries, another buffer is allocated to continue the trace. Buffer allocation continues until a maximum of 30 buffers is allocated for the TRS topology trace. When all buffers of the TRS topology trace are full of trace entries, the trace wraps back to the first entry on the first buffer of the trace table.
The TRS topology trace table is pointed to from the TRDAT.
The following information about the TRS topology trace table is included
in the TRDAT:
- A pointer to the first buffer of the TRS topology trace
- A pointer to the last buffer of the TRS topology trace
- A pointer to the current buffer of the TRS topology trace
- A pointer to the current TRS topology trace entry
- The number of trace records that have been used in the current buffer of the TRS topology trace
- The number of times the TRS topology trace table has wrapped
- The number of TRS topology trace table buffers allocated
Figure 1 shows the TRS topology trace table format:
Figure 1. TRS common topology
trace table with two buffers allocated
The first X'18' bytes of the allocated buffer
of TRS topology trace table is the header, which contains the following
information:
- Byte (hex)
- Contents
- 00–03
- TRS topology trace control block ID – C"TRTR"
- 04–07
- 0
- 08–0B
- Address of the previous buffer of the TRS topology trace. The previous buffer pointer is 0 for the first buffer of the trace.
- 0C–0F
- Address of the next buffer of the TRS topology trace. The next buffer pointer is 0 for the last buffer of the trace.
- 10–13
- Timestamp (first word) when the trace most recently wrapped back to the beginning. The timestamp is present only on the first buffer of the TRS topology trace.
- 14–17
- Prior timestamp (first word) when the trace wrapped back to the beginning. The timestamp is present only on the first buffer of the TRS topology trace.