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Maintenance Data Link for European E3/E2 Telco Services

IP.com Disclosure Number: IPCOM000110856D
Original Publication Date: 1994-Jan-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Kauffmann, JA: AUTHOR [+3]

Abstract

The Maintenance Data Link (MDL) carries performance information and control commands across the Network Interface (NI). Performance information appearing in one direction of transmission is a presentation of the quality of transmission in the opposite direction.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Maintenance Data Link for European E3/E2 Telco Services

      The Maintenance Data Link (MDL) carries performance information
and control commands across the Network Interface (NI).  Performance
information appearing in one direction of transmission is a
presentation of the quality of transmission in the opposite
direction.

      Occurrences of transmission error events indicate the quality
of transmission.  Examples of transmission error events are BIP-4
(Bit Interleaved Parity) errors, Frame Synchronization (Bit error)
event, etc.

      The performance report is sent each second using a bit-assigned
message structure.  The performance report contains information for
each of the previous one-second intervals.  Counts of events are
accumulated in each contiguous one-second interval.  At the end of
each one-second interval, a counter is incremented.

The frame formats are defined by different CCITT standards as
described below:

Communication Line Rates:

o   E3: 34.368 Mb/s

o   E2:  8.448 Mb/s

Standard CCITT Frame Formats:

o   E3: G.751 or G.753 (and G.703)

o   E2: G.742 or G.745 (and G.703)

This disclosure involves the following modification of the standard
formats:

o   Note that in CCITT Frame Formats G.742, G.745, G.751, G.753,
    three nibbles are defined as justification bits for multiplexed
    applications.  In a clear channel operation defined herein, these
    bits are used to carry payload data.

o   The standard formats do not contain the provision for a
    Maintenance Data Link Channel.  However, they contain spare time
    slots (frame bits) that are defined and used herein as a
    Maintenance Data Link Channel equivalent to the ones offered in
    the U.S.  for T1 and T3 communication services.

o   The standard formats do not provide for the detection of bit
    errors within the frame.  The last four bits of the information
    field are defined herein to provide a BIP-4 covering all the bits
    in a frame in order to detect bit errors in the received frame at
    the far end.  The count of frames containing errors gives an
    indication of the performance level of the communication link.

      Within each frame, one bit is used as a maintenance data link
for reporting performance messages to the far end adapter of the
link.  The data rates for the maintenance data link are as follows:

Maintenance Data Link line rates:

o   E3 (G.751):   22.375 Kb/s

o   E3 (G.753):  16.000 Kb/s

o   E2 (G.742):   9.962 Kb/s

o   E2 (G.745):   8.000 Kb/s

      In G.751 and G.742, the bit position used for the maintenance
data link must...