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Interface Specifications
Figure 1-2
Features
The PA-4E1G provides the following features and capabilities:
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Note
PA-4E1Gs are available as spare parts PA-4E1G-120(=) and PA-4E1G-75(=).
Interface Specifications
Each PA-4E1G interface is available in either balanced (120-ohm) or unbalanced (75-ohm) mode; a
unique port adapter supports each type. Neither the balanced and unbalanced modes nor the balanced
and unbalanced cables are interchangeable; you cannot configure a balanced port to support an
unbalanced line, nor can you attach an interface cable intended for a balanced line to an unbalanced port.
Balanced interfaces typically use three conductors and three signal states: high, low, and ground. The
high and low signals mirror each other. Unbalanced interfaces use only two signals: signal and ground.
You can discover the mode of each interface by examining the agency approval label on each port
adapter, or by using the show controller cbus command.
Following is an example of discovering whether the PA-4E1G is in balanced or unbalanced mode:
Router# show controllers cbus
Serial1/1/0, applique is G.703 Unbalanced
[remainder of displayed text omitted from example]
Serial1/1/1, applique is G.703 Unbalanced
[remainder of displayed text omitted from example]
The PA-4E1G interface is divided into 32 time slots or frames. (See
PA-4E1G Serial Port Adapter Installation and Configuration
1-2
PA-4E1G—120-Ohm, Balanced (Front Panel View)
Provides framed and unframed service access, E1 (2.048 Mbps) line speeds over unbalanced 75-ohm
or balanced 120-ohm cable, with 15-pin, D-shell (DB-15) receptacles on the port adapter
Operates over E1 leased-line services, and provides ITU-T G.703 with high-density bipolar of order
3 (HDB3) line encoding
Operates with either an external or internal clock signal, and runs at wire speed
Provides for local and remote loopback testing services
Allows you to fractionalize a data stream into a single channel from 64 kilobits per second (kbps)
to 1984 kbps
Provides G.704 framing for n x 64-kbps service support (where n = 1 to 31)
Support for 4-bit cyclic redundancy check (CRC4) to provide and ensure data integrity
Support for point-to-point connections to supported platforms
Eliminates the need for a separate, external data termination unit that is typically used to convert
standard serial interfaces, such as V.35, to E1-G.703/G.704
Chapter 1
Overview
E1 G.703/G.704-120 OHM
Figure
1-3.)
OL-3065-05
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