Avaya CMC1, Maintenance Procedures

Page: 35 / 426

Maintenance strategy
Protocols
Maintenance Procedures 35
December 2003
Inside the system, data transmission appears in one of two forms:
• Raw digital data, where the physical layer protocols, like DCP, are stripped at the incoming port
and reinserted at the outgoing port.
• Pulse Code Modulation (PCM)-encoded analog signals (analog transmission by a modem), the
signal having been digitized by an analog-to-digital coder/decoder (CODEC) at the incoming
port.
Layer-2 protocols
Layer-2 protocols are given below:
• 8-bit character code — Between the DTE and DCE equipment. Depending on the type of
equipment used, the code can be any proprietary code set.
• Digital multiplexed interface proprietary — Between the originating and the destination DCE.
Family of protocols for digital transmission.
• Voice-grade data — Between the originating and the destination DCE. For analog transmission.
Protocol states
Table 6, Protocol states for data communication, on page 35 summarizes the protocols used at various
points in the data transmission stream. See Figure 3, Intra-port and Inter-port data transmission states, on
page 33.
Table 6: Protocol states for data communication
Transmissio
n type
Incoming
DTE to
DCE
OSI
layer
1
1 OSI means Open Systems Interconnect
Protocols DTE to
DCE DCE to system
port
Inside system
Analog Modem 1 RS-232, RS-449,
or V.35 analog PCM
2
2 PCM means Pulse Code Modulated
2 8- or 10-bit code Voice-grade
data Voice-grade data
ADU 1 RS-232 ADU
proprietary Raw bits
2 Asynchronous 8-
bit code Asynchronous
8-bit code DMI
3
3 DMI means Digital Multiplexed Interface
Digital Data
Module 1 RS-232, RS-449,
or V.35 DCP or BRI Raw bits
2 8-bit code DMI
3
DMI
3
Digital
Signal
Level 1
(DS1) 1 Any DS1 PCM
2
or raw bits
2 8-bit code DMI
3
or voice-
grade data
DMI
3
or voice-
grade data