Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1999-06-28
2003-07-29
Nguyen, Chau (Department: 2663)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S388000
Reexamination Certificate
active
06600742
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates to an SDH transmission unit for use with a network based on an SDH (Synchronous Digital Hierarchy) transmission system, and more particularly to an SDH transmission unit having a function as an ADM (Add-Drop Multiplexer).
2) Description of the Related Art
In an SDH transmission network (called SONET (Synchronous Optical Network) in the North America), high speed (source) networks which handle transmission (signal) frames of a predetermined transmission capacity (rate) of OC-N [Optical Carrier-level N: N=192 (approximately 10 Gb/s)/48 (approximately 2.4 Gb/s)/12 (approximately 600 Mb/s) and so forth) are implemented at present, and as a network application (network configuration) of it, for example, such terminal/linear, regenerator, ring [UPSR (Unidirectional Path Switched Ring)/BLSR (Bidirectional Line Switched Ring)] as shown in
FIGS. 47
to
49
are available.
Referring to
FIGS. 47
to
49
, an ADM (SDH transmission unit)
100
having a main function of time slot assignment (TSA) of performing Add/Drop/Through processing in accordance with a line (signal) unit mapped to an OC-N signal frame mentioned above uses functions corresponding to such various applications as mentioned above so that the various applications can be applied by the single unit.
Where, for example, a high speed side line (OC-N) has a ring (UPSR) configuration as shown in
FIG. 50
, an ADM (node A) handles (accommodates) a line capacity for a sum total (=N channels) of channels (STS-1×n) allocated to communication among nodes (stations) B, C and D on the ring, and adds the same signal to signals in the EAST/WEST directions of the ring or selects one of same signals sent from the EAST/WEST directions to the ADM (node A) as a termination side node with respect to the node C which has a higher line quality and drops a pertaining signal channel (low speed line signal) to the low speed line (tributary) side.
A tributary block (TB) which performs processing of low speed side lines (OC-N/4, N/16, N/64 and so forth) can apply various applications such as a ring configuration similar to that on the high speed line side described above and a 1+1 redundancy configuration of the work/protection systems. Therefore, the TB is constructed taking an interface between various functioning boards (units) into consideration which is used to satisfy accommodation compatibility of interface (IF) units corresponding to various transmission levels (capacities) or applications.
In particular, for example, as shown in
FIG. 51
, a TB
200
has a plurality of IF units (IF boards (cards))
300
for performing production/termination processing of OC-n transmission frames corresponding to various transmission levels (OC-n: when n<N and N=192, for example, n=48/12/3 and so forth) of low speed side lines. Where the IF boards
300
accommodate low speed lines (tributary networks) of a 1+1 redundancy configuration, they are used for work units/protect units, but where the IF boards
300
accommodate low speed lines of a ring configuration, they are used for EAST/WEST side transmission units.
Each of the IF boards
300
includes, for a transmission line (line: OC-n level) input signal, an O/E (opto-electric) conversion section
301
, a frame synchronism protection section
302
, a descrambling section
303
, an SOH reception processing section
304
, a byte demultiplexing section
305
, a supervision section
306
for various alarms such as an AIS and transfers a signal demultiplexed from a received OC-n transmission frame to a routing block (RB)
400
which is positioned in the next stage and performs low speed side line time slot assignment.
On the contrary, each of the IF boards
300
includes, for a signal transferred from the RB
400
after low speed side time slot assignment (Add assignment), a byte multiplexing section
307
, an SOH insertion section
308
, a scrambling section
309
, an E/O conversion section
310
, a BIP (Bit Interleaved Parity) processing section
311
and so forth and performs multiplexing of the Add assigned signal into a transmission frame (OC-n level), addition of an SOH to the multiplexed transmission frame, scramble coding, E/O conversion and so forth to produce a transmission line (OC-n level) output signal.
It is to be noted that the RB
400
performs switching operations (switching/bridging and so forth) of the low speed side lines suitable for the various applications described above. For example, the RB
400
has a function
40
a
of performing, where the 1+1 redundancy configuration is employed, a line switching (line selection) process in accordance an APS (Automatic Protection Switch) protocol for a transmission line, but performing, where the ring (UPSP) configuration is employed on the OC-n described above, selection processing of signals in the EAST/WEST directions. The RB
400
further has a time slot assignment (Add/Drop/Through: TSA) function
40
b
for low speed side lines. Consequently, the RB
400
can cope with various applications to the low speed side lines and allows connection to a high speed side line (high speed block
500
).
The high speed block (HB)
500
includes an interface section
501
for interfacing with the high speed line side (a high speed circuit signal), and a TSA function
502
for performing time slot assignment (Add/Drop/Through) on the high speed line side and accommodates the low speed side lines by means of the TB
200
(RB
400
) However, since the number of accommodated slots for the IF boards (cards)
300
(the number of the IF boards (cards)
300
) for the low speed side lines (OC-n) which can be accommodated in one TB
200
(RB
400
) has a physical restriction, for example, a plurality of (m) RBs
400
are accommodated for the high speed side line capacity (N channels) as shown in
FIG. 52
so that all of the high speed side lines (for N channels) are accommodated in all of the RBs
400
.
For example, if the high speed side lines have a ring configuration (UPSR) which handles signals (transmission frames) of the OC-192 (10 Gb/s) level, then the HB
500
is constructed with a signal processing capability of the OC-192 (10 Gb/s) capacity, and, for example, four RBs
400
having a signal processing capability of the OC-48 (2.4 Gb/s) level are accommodated in the HB
500
. Further, four IF boards
300
are accommodated in each of the RBs
400
if the IF boards
300
are for the OC-12 (600 Mb/s) level, but one IF board
300
, which is one fourth that in the case just described, is accommodated in each of the RBs
400
if the IF board
300
is for the OC-48 (2.4 Gb/s) level.
In short, a number of IF boards
300
corresponding to a transmission level applied to the low speed side lines equal to the number of slots corresponding to the processing capability (capacity) of the TB
200
(RB
400
) are allocated to the TB
200
(RB
400
). If it is assumed that the total signal capacity when the IF boards
300
for the OC-n level are accommodated in the full slots is the processing capacity of the TB
200
, then when the IF boards
300
for the OC-(n×4) level are accommodated, the number of slots in which IF boards
300
are accommodated is reduced to one fourth, thereby providing compatibility in mounting of various IF boards
300
.
In particular, the ADM
100
described above is designed with the OC-n level set as a basic transmission level taking accommodation compatibility of the IF boards
300
for various transmission levels in the TBs
200
and the signal capacity for the high speed side lines (HB
500
) (the processing capacity of the TBs
200
) into consideration.
However, the ADM
100
described above has a subject to be solved in that, if IF boards
300
having a capacity smaller than the basic transmission capacity OC-n (for example, a capacity of an OC-n/4 or the like) are accommodated in a TB
200
, then this directly results in reduction of the processing capacity of the TB
200
.
For example, such an ins
Hiromori Masaki
Ito Hirokazu
Matsuo Hiroyuki
Matsuzaki Seiji
Fujitsu Limited
George Keith M.
Katten Muchin Zavis & Rosenman
Nguyen Chau
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