Table 11: Control Word Bit Description; Figure 19: Control Word Bit Structure - Alcatel-Lucent 7210 SAS M Service Manual

Circuit Emulation (Cpipe) Services
Control Word
The structure of the control word is mandatory for SAToP and is shown in
The control word descriptions are listed in the

Table 11: Control Word Bit Description

Bits 0 to 3
L (Local TDM Failure)
R (Remote Loss of
Frames indication)
M (Modifier)
Sequence number
Page 134

Figure 19: Control Word Bit Structure

Bit(s)
The use of bits 0 to 3 is described in RFC 4385. These bits are set to
'0' unless they are being used to indicate the start of an Associated
Channel Header (ACH) for the purposes of VCCV.
The L bit is set to 1 if an abnormal condition of the attachment
circuit such as LOS, LOF, or AIS has been detected and the TDM
data carried in the payload is invalid. The L bit is cleared (set back
to 0) when fault is rectified.
The R bit is set to 1 if the local CE-bound inter-working function
(IWF) is in the packet loss state and cleared (reset to 0) after the
local CE-bound IWF is no longer in the packet loss state.
The M bits are a 2-bit modifier field. For SAToP, M is set to 00 as
per RFC 4553.
The sequence number is used to provide the common pseudowire
sequencing function as well as detection of lost packets.
Table 11:
Description
7210 SAS M Services Guide
Figure 19.