Section 311-580-20B
030-101527 Rev. B
10
0407IBRB
T1
ORB
3115-80
Test Access
Digroup
(Split Access)
TL1 PM Commands/Responses to
Performance Monitoring System
Figure 7.
TL1 PM Retrieval Diagram - Intrusive Mode Shown
DCS or other Test
Head Device
Encapsulated
TL1 Messages
in ESF Data
Link
TL1z
Command/
Response
TEST
RESOURCES
T1 LINE
RPTR
CSU
T1
OFFICE
RPTR
3115-80
CSU
NPRM
PRM
CSU
PRM
NIU
NPRM
MONITOR
NETWORK MONITOR / TEST ACCESS
TL1 Reporting to Performance
Surveillance System
Figure 8.
NPRM Application Diagram
T1
LINE RPTR
6.10.2
The TL1 commands conform to standard commands
such as RTRV-PM, INIT-REG, etc. The protocol is a modified
X.25 LAPB. A generalized diagram of this procedure is shown
in Figure 7.
6.11
Real Time Performance Reporting
Real-time PM reporting from both the facility and CPE can be
provided using one of two methods, SPRMs (Supplemental Per-
formance Report Messages) or NPRMs (Network Performance
Report Messages). Both methods are similar in structure but dif-
fer in content. Both methods also conform to ANSI
Specifications described in T1.403-1998. These message for-
mats are similar to ANSI T1.403 PRMs (Performance Report
Messages) that is sent toward the network at 1-second intervals
via the ESF Data Link by the CPE CSU. The NPRM or SPRM
messages allow network equipment to determine if the T1 signal
was in error before being sent to the customer. It also indicates
if the T1 signal from the CPE contained errors before it enters
the network.
6.11.1
Network Performance Report Message
6.11.1.1
The NPRM mode operates by sending an NPRM mes-
sage toward the network once every second. This message
contains performance information that covers the last four sec-
onds of operation. This NPRM is inserted into the Data Link by
the NIU after" the 1-second PRM from the customer CSU that
is passed through the NIU. Note that the CSU may not generate
PRMs or may be operating in the PUB 54016 mode that does not
use PRMs. The NIU will always generate an NPRM whether
CSU PRMs are generated or not. In order to allow network
monitoring equipment to differentiate between CSU PRMs and
NPRMs, the NPRM is assigned a SAPI address of 16, allowing
easy differentiation from a CSU PRM that has an assigned SAPI
address of 14. A generalized network diagram of NPRM report-
ing and collection is illustrated in Figure 8.
6.11.1.2
NPRM is generally preferred to SPRM since it pro-
vides more detailed information, and does not modify the
customer CSU PRMs thereby guaranteeing compatibility with
all T1.403-1995 compliant CSUs.
6.11.2
Supplemental Performance Report Message
The Supplemental Performance Report Message (SPRM)
mode, like the NPRM mode, consists of a performance report
message that is sent toward the network at 1-second intervals.
6.11.2.1 SPRM Mode - ESF Circuits
When installed on ESF circuits and the CSU is generating
PRMs, the 3115-80 will actually modify bits in the customer-gen-
erated PRM in order to provide performance information on
the circuit at the point of the network interface. This modified
PRM is known as the Supplemental Performance Report Mes-
sage (SPRM). Typically, the R", U1" and U2" bits of the
customer PRM are the modified bits. The R bit channel is used
to flag whether or not SPRM information had been added to the
PRMs and, if so, what mode of SPRM is in use. The U1 and U2
bits are used to multiplex the additional performance informa-
tion into the PRMs.
6.11.2.2 SPRM Mode - SF Circuits
When installed on SF circuits and frame format conversion is en-
abled (i.e., network is ESF framed), the 3115-80 will generate its
