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61225236L1-5A Issue 1, August 2003 5
5. OPERATION
Test Capabilities
The SHDSL T1/E1 NTU has the following test capabil-
ities:
• Self diagnostics
• Local loopbacks
• EOC initiated remote loopbacks
• Inband remote loopback detection (E1 mode only)
• Internal bit error rate tester (BERT)
Self Diagnostics
The SHDSL T1/E1 NTU performs self diagnostic tests
of its Read Only Memory (ROM), Random Access
Memory (RAM), LEDs, and non-volatile configuration
setting upon power-up.
Local and Remote Loopbacks
For troubleshooting purposes, the SHDSL T1/E1 NTU
provides three types of loopback tests.
1. Dual sided
2. Network
3. Customer
Inband Loopback Detection
Inband remote loopback response is supported on the
E1 port. The SHDSL T1/E1 NTU supports V.54 and
PN127 inband signalling protocols.
BERT
The SHDSL T1/E1 NTU contains a built-in Bit Error
Rate Test (BERT). The BERT involves injecting and
detecting a Pseudorandom Binary Sequence (PRBS)
toward the network on the selected payload (i.e. G.703
or entire SHDSL payload). The PRBS used in the
SHDSL T1/E1 NTU is PRS15 as defined in ITU-T
0.150 and 0.151. It is also known as
2e15 – 1
pattern.
Customer Port
The SHDSL T1/E1 NTU operates in either E1 mode or
T1 mode.
E1 Mode
In E1 mode the port features are as follows:
• Carries information at the rate of 2.048 Mbps
• Uses CCS framed format with or without CRC-4
• Operates in either Alternate Mark Inversion (AMI)
or High-Density Bipolar 3 (HDB3) line code
• Provides programmable timeslot idle pattern
• Supports ISDN-PRA V3 service
• Displays additional status information via a local
VT100 management screen
See Table 5 for E1 port statistics definitions.
T1 Mode
In T1 mode the port features are as follows:
• Carries information at the rate of 1.544 Mbps
• Uses Superframe Format (SF) or Extended Super-
frame Format (ESF)
• Operates in either Alternate Mark Inversion (AMI)
or Bipolar w/8-Zero Substitution (B8ZS) line code
• Provides programmable timeslot idle pattern
• Monitors the Facility Data Link (FDL) for loopback
commands
• Displays additional status information via a local
VT100 management screen
See Table 6 for T1 port statistics definitions.