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RTM Host Interface
Using the request/response unit (RU) formats given at the end of this section, an
SNA host application program can communicate with the RTM feature in the 3708
and can solicit RTM information from the following sources:
• One logical unit (LU)
• All LUs
• All LUs with nonzero RTM data.
The host application program can reset the RTM logs. Also, the host application
program may change the parameters affecting collection of RTM information by
updating the following on a one-or-all LU basis:
• Set RTM boundaries
• Set RTM definition code
• Activate/deactivate RTM data collection (host only)
• Return unsolicited data when a session ends
• Return unsolicited data when a counter overflows.
Note: An ACTPU/DACTPU causes the control unit to revert to the defaults for
RTM parameters. All RTM data in the 3708 is lost.
Solicited RTM Information
When a request is made to the 3708 on an SSCP-PU session via a host request
containing an RTM major vector, the 3708 examines the request. If the request is
accepted, a positive response is returned to the host. If the host request does not
solicit any data, the 3708 considers the request completed after sending the positive
response and updating the appropriate RTM logs; it then reverts to contention state.
If the host request is soliciting information, one or more 3708 responses are then
returned to the host as the solicited response. Each of these responses contain data
pertinent to a specific LU attached to the 3708. If the reset bit is included in the
request, the RTM data for that LU is reset upon transmission of the record. This
reset function includes the RTM counters (including overflow) and the total
transaction time.
If an outbound request is intended for a specific LU, it must contain an SNA
address list with one element providing the 3708 with the local address of the LU.
Each inbound request contains an SNA address list with two elements: the first
element provides the local address of the PLU; the second element provides the local
address of the associated SLU. Including of local addresses in the inbound RUs
allows the host RTM application program to correlate response time data with the
associated PLU and SLU session pair. Translation of the addresses into 8-byte
EBCDIC names is the responsibility of one or more upstream nodes.
A session correlation vector is also returned with the RTM data that is unique to
each session pertaining to a specific 3708. This allows a host application program to
determine the appropriate session pair after that session has been unbound, provided
that the application program was able to determine the session identity previously.
The RTM datais only collected when a device is in an LU-LU session. When
unsolicited RTM transmission on UNBIND is not supported, the data associated
with each logical terminal may pertain to multiple LU-LU sessions. Should multiple
session data be present, a flag is set in the appropriate RTM log indicating this. The
flag is reset when the RTM data is sent inbound. Note that the session correlation
number is updated upon acceptance of each BIND for that LV.
8-22
IBM 3708
Description
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