The MIB module contains ATM Trunk statistics.

TERMINOLOGY
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PVC: Permanent Virtual Circuit
OAM: Operation and Management
CRC: Cyclic redundancy check
AIS: Alarm Indication Signal
TDM: Time Division Multiplex
FERF: Far End Receive Failure
CPS: Common Part Sub-layer
PDU: Protocol Data Unit
HEC: Header Error Control 
DSP: Digital Signal Processing
CID: Channel Identifier
UUI: User-to-User Information
VoIP: Voice over IP
CCS: Common Channel Signaling 
VoAAL2: Voice over AAL2
SDU: Service Data Unit
HDLC: High Level Data Link Control
SAR: Segmantation and Reassembly

External AIS - is an Alarm Indication Signal associated
with a maintenance alarm detected on a defective 
maintenance span, that is transmitted in the direction 
of the defect as a substitute for normal signal. 
The purpose is to show the downstream  entities that 
a defect has been identified and to prevent other 
maintenance alarms consequent to this first defect.
External AIS bit stream is represented by an all 1's 
signal. 
Ref - ITU-T Rec. M.20 sec. 5.4.2 a 

External RAI - is a Remote Alarm Indication signal 
that is transmitted upstream from an entity that has 
detected defects persisting long enough to constitute 
a received signal failure. Its purpose is to report in 
the backward direction that there is an interruption 
of service in the forward direction.
The forward direction is from the originating end of
the alarm to the remote end.
The backward direction is from the remote end to the
orginating end of the alarm.
Ref - ITU-T Rec. G.704 section 2.1.3.1.3 
      I.366.2 - ANNEX N

External Connection AIS - is a Alarm Indicating Signal 
transmitted in the downstream direction from the AAL 
type 2 connecting point that first detects a defect 
affecting the AAL type 2 connection; this includes 
defects indicated by lower layers.
Ref - ITU-T Rec. I.610 sec 6.2.2.1.1.1 

External Connection RDI -  is a signal transmitted upstream 
by an AAl type 2 endpoint that is in an alarm state as the 
result of having received an AAL type2 connection AIS or 
having detected a defect that affects the AAL type2 
connection. 

All ATM alarm definitions are specified in I.610 
(ITU standard).