IBM 3708 Description page 260

Should a counter-overflow occur, collection of RTM data for that logical terminal is
suspended until the RTM data is reset. This is done when a host request is received
from the host for that terminal (or all terminals) containing a Reset vector, or when
a request is received that changes the boundaries or definition for that LU, or when
data is sent unsolicited to the host.
When the host requests RTM data from a specific LU whose RTM data is zero, all
the RTM data is returned for that device. The no-data flag is set. This provides the
host application program with the ability to determine the actual parameters
associated with a given LV, regardless of the data contained in its RTM log.
When the host requests only nonzero RTM data from all LUs, only those LUs with
nonzero RTM data responds, except for the last LV which responds regardless of its
RTM data content.
While a request unit (RV) is in process, additional REQMS or RTM requests are
rejected by the 3708 until a positive or negative response is received for the
transmitted RV. Also, if the 3708 is busy processing an unsolicited alert or RTM
response, the PU is in send state and any requests from the host are rejected until
the unsolicited operation is completed and a response is received for the transmitted
responses.
Unsolicited RTM Information
Besides allowing solicited information to flow on the SSCP-PU session, the host can
enable the 3708 to transmit unsolicited RTM information when UNBIND is
processed for an LU-LU session or when an RTM counter overflows. When one of
these conditions occurs, the associated RTM information is scheduled within the
3708 for transmission to the host RTM application program on the SSCP-PU flow.
Once transmitted, the data for that logical terminal is reset.
If the transmission was caused by an RTM counter overflow, a flag is set in the
RTM data to indicate the potential loss of data. If the transmission was caused by
an UNBIND and another BIND is accepted for that logical terminal before the
RTM information can be transmitted, additional responses are discarded until the
RTM data is transmitted. The session correlation vector is updated after the RTM
information is transmitted. A potential loss of data because of the new BIND is
indicated in the next RTM transmission (not the transmission just sent).
Negative Responses
The following negative responses may be returned from the 3708 in response to an
REQMS or NMVT request:
1003 Negative Response:
An NS (network services) header was received, but (1) it
was neither REQMS nor NMVT, or (2) it was NMVT but RTM is not supported.
The request is rejected and error recovery is the responsibility of the sender.
1007 Negative Response:
An invalid NS header was received. The request is
rejected and error recovery is the responsibility of the sender.
0815 Negative Response: Another NMVT request was in process in the 3708 when
this request was received. The request is rejected and error recovery is the
responsibility of the sender.
Chapter 8. Network Management and Problem Determination
8-23