Table of Contents
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Chapter 1
Overview
The PA-MC-T3-EC does not support the aggregation of multiple T1 lines (called inverse multiplexing
Note
or bonding) in hardware for higher bandwidth data rates. MLPPP may be used for this purpose in
software.
The T3 section of the PA-MC-T3-EC supports the maintenance data link (MDL) channel when using
c-bit parity framing as well as local and network loopbacks. The T1 section of the PA-MC-T3-EC
supports facilities data link (FDL) in Extended Superframe (ESF) framing, as well as various loopbacks.
Bit error rate (BER) testing is supported on each of the T1 lines, although a test may not be active on
more than one T1 line at a time. BER testing may be done over a framed or unframed T1 signal.
Unchannelized T3 Overview
In the unchannelized mode of operation, a T3 link provides a single high speed user data channel, rather
than being multiplexed into 28 T1 lines. The data channel appears to the system as a serial interface that
may be configured to use the full T3 bandwidth or a smaller portion of the T3 bandwidth. No industry
standard exists for subdividing the T3 bandwidth, but the PA-MC-T3-EC is compatible with the
proprietary formats of five vendors of data service units (DSUs), when used at the far end of the T3 link.
In unchannelized T3 mode, the T3 section sports the maintenance data link (MDL) channel when using
c-bit parity framing as well as local and network loopbacks. Bit error rate (BER) testing is supported on
the T3 link. The PA-MC-T3-EC supports Cisco High-Level Data Link Control (HDLC), Frame Relay,
PPP, and Switched Multimegabit Data Service (SMDS) Data Exchange Interface (DXI) encapsulations
over the serial interface.
T3 Specifications
The PA-MC-T3-EC T3 port is designed to receive and transmit at the DSX-3 level while driving and
receiving from 75-ohm coaxial cables (ATT 734A or equivalent quality coaxial cable). The T3 port
connects directly to any equipment with DSX-3-level BNC connectors.
Table 1-1
Table 1-1
Parameter
Line rate
Line code
Impedance
Output pulse shape
Input signal
Output signal
The coaxial shield side of the T3 BNC connectors is connected to the router chassis ground.
Note
OL-10589-02
lists the specifications that the T3 front end is designed to meet.
Specifications for the T3 Front End
Specification
44.736 Mbps (±20 ppm)
B3ZS (bipolar with three-zero substitution)
75 ohms
ANSI T1.102, pulse amplitude is between 0.36 and 0.85 volts peak
0.035-1.1 volts peak
Able to drive 450 feet (135 meters) of 75-ohm coaxial cable (734A
or equivalent) and meet pulse shape template
PA-MC-T3-EC Port Adapter Installation and Configuration
Unchannelized T3 Overview
1-3
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