Cisco AS5800 Specifications download pdf (Page 70)

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Cisco AS5800 Operations, Administration, Maintenance, and Provisioning Guide

DOC-7810814=

Chapter 2 Commissioning

Task 3. Enabling the T3/T1 Controllers

Table 2-6 describes some of the T3 and T1-controller concepts that are applied in the previous steps.

Table 2-6 Controller Terms and Descriptions

Concept Description

Framing type Defines the control bits and data bits.

For T3s, Cisco supports:

• M23—M23 multiplexer framing (default)

• C-bit—C-bit parity framing

For T1s, Cisco supports:

• ESF—Extended super frame. Required for 64 KB operation on DS0s. ESF requires 2k-framing bits

for synchronization. The remaining 6k is used for error detection, CRC, and data link monitoring.

ESF is recommended for PRI configurations.

• SF—Super frame. SF (D4) is used in channel bank robbed bit signalling (RBS) configurations. The

in-band signaling occurs within the 6th and 12th frames. SF uses the framing bit for frame

synchronization. SF is not recommended for PRI configurations.

Line code type An encoding method used to allow synchronous data to be transmitted in a compatible format. Common

line codes are RZ (return to zero), NRZ (non-return to zero), B8ZS, AMI, and HDB3.

• AMI—Alternate mark inversion. Signal transitions are referenced by a binary 1 (mark). AMI is used

on older T1 circuits. B8ZS is more reliable than AMI.

• B8ZS—Most popular line-code scheme used in North America. To maintain clock synchronization,

B8ZS replaces string 8 binary 0s with variations. B8ZS is more reliable than AMI, and it should be

used with PRI configurations.

Clock source Refers to both timing and synchronization of the T1 carrier. Timing is encoded within the transmitted

data signal, and it ensures synchronization throughout the network.

Clocks are prioritized by slot number (slot 0 to slot 5). The highest priority clock is selected from the

card in slot 0. If this clock fails, the highest priority clock from the card in slot 1 becomes the default

clock, and so forth.

Timeslot

assignment

Timeslots are assigned to channels. For T1 PRI scenarios, all 24 T1 timeslots are assigned as ISDN PRI

channels. After timeslots are assigned by the pri-group command, D-channel serial interfaces are

automatically created in the configuration file (for example S1/0/0:0:23, S1/0/0:1:23, and so on).

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Cisco AS5800 Specifications Page 70