Patent EP0818940A2 successfully refreshed from Google Patents.
EP0818940A2
Expired / Lapsed
EP
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Self-healing line switched ring for ATM traffic
Assignee: Nortel Networks Ltd
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Filing: 1997-07-09
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Granted: —
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Expires: 2017-07-09
Abstract
Abstract The invention provides for a method for transporting a SONET/SDH formatted asynchronous transfer mode (ATM) signal and/or a synchronous transfer mode (STM) signal on a line switched ring over a unidirectional path. The SONET formatted ATM signal comprises cells mapped into a STS-Mc or m×STS-1s while the STM signal comprises STS-1s/VTs mapped STS-W. A unidirectional line switched ring is provided for transporting the STM STS-W using a unidirectional path switched protection protocol and the ATM STS-Mc using a unidirectional line switched protection protocol. A ring node comprises input and output ring interfaces, an STS management block, an ATM cell management block, and a non-ATM payload management block. The STS management block routes the traffic to the ATM cell management block and to the non-ATM payload management block, according to the traffic type. The STS management block also provides the UPSR protection for the STS-1s and ULSR protection for the STS-Mc. The ATM cell management block maps the add ATM cells received from the ATM ports into the STS-Mc signal, and delineates the cells from the STS-Mc to present them to the ATM ports. The non-ATM payload management block routes STM VTs or STS-1s to/from the non-ATM ports.
Inventors
- 👤 Donald Russell Ellis
- 👤 Brent E. Allen
- 👤 David Wright Martin
- 👤 Edward Ryszard Sokolowski
- 👤 Patrick M. Mceachern
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 14:27
CPC Classifications
H; H04; H04L; H04L49/00; H04L49/10; H04L49/104; H04L49/105; H04J; H04J3/00; H04J3/02; H04J3/08; H04J3/085; H04Q; H04Q11/00; H04Q11/04; H04Q11/0428; H04Q11/0478; H04J2203/00; H04J2203/0001; H04J2203/0003; H04J2203/0005; H04J2203/0028; H04J2203/0039; H04J2203/0042; H04J2203/0057; H04J2203/006; H04L12/00; H04L12/54; H04L12/56; H04L12/5601; H04L2012/5603; H04L2012/5609; H04L2012/5612; H04L2012/5625; H04L2012/5627
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
129 words
A method for communicating information over a
synchronous (SONET/SDH) line switched ring having a plurality (K)
of communication terminals connected to a first and a second
transmission line, comprising the steps of: at each terminal (k), inserting an outgoing signal onto said first
transmission line along a first direction of transmission defined from
said terminal (k), towards an adjacent terminal (k+1), wherein (k) is an
integer between 1 and (K) giving the sequential position of said node
(k) in said ring; at each said terminal (k), receiving an incoming signal over said
first transmission line from an adjacent terminal (k-1), along said first
direction of transmission; and operating said plurality of communication terminals according
to a unidirectional protection protocol upon detection of a failure
condition in said incoming signal.
Claim 2
Dependent Claim
28 words
A method as claimed in claim 1, wherein said incoming
signal is an incoming asynchronous transfer mode (ATM) STS-Mc and
said outgoing signal is an outgoing ATM STS-Mc.
Claim 3
Dependent Claim
46 words
A method as claimed in claim 1, wherein said incoming
signal is an incoming STS-N comprising an incoming non-ATM STS-W
and an incoming ATM STS-Mc, and said outgoing signal is an
outgoing STS-N comprising an outgoing non-ATM STS-W and an
outgoing ATM STS-Mc, wherein M+W=N .
Claim 4
Dependent Claim
23 words
A method as claimed in claim 3, wherein each of said
incoming and outgoing STM STS-W comprises a plurality of virtual
tributaries (VT).
Claim 5
Dependent Claim
115 words
A method as claimed in claim 2, wherein said
unidirectional protection protocol operates according to a variant of
BellCore GR-1230-CORE standard, comprising unmodified assignments
for all bytes of the transport overhead (TOH) field of said incoming
signal, but: a modified assignment of bits 0-4 of the K1 byte, wherein the
span code (LP-S, SF-P) is used for a lockout of protection code (LP-P),
span code FS-S is used for a signal fail on protection code (SF-P), span
codes (SF-S), (SD-S), (MS-S) and EX-S), and reverse request codes (RR-S)
and (RR-P) are eliminated; and a modified assignment of bits 6-8 of the K2 byte, wherein the
code "Bridges and Switched" is used for a code "Switched".
Claim 6
Dependent Claim
137 words
A method as claimed in claim 3, wherein said
unidirectional protection protocol operates according to BellCore GR-1230-CORE
standard for said incoming and outgoing non-ATM STS-W
and according to a variant of BellCore GR-1400-CORE standard for said
incoming and outgoing ATM STS-Mc, said variant comprising
unmodified assignments for all bytes of the transport overhead (TOH)
filed of said incoming signal, but: a modified assignment of bits 0-4 of the K1 byte, wherein the
span code (LP-S, SF-P) is used for a lockout of protection code (LP-P),
span code FS-S is used for a signal fail on protection code (SF-P), span
codes (SF-S), (SD-S), (MS-S) and EX-S), and reverse request codes (RR-S)
and (RR-P) are eliminated; and a modified assignment of bits 6-8 of the K2 byte, wherein the
code "Bridges and Switched" is used for a code "Switched".
Claim 7
Independent Claim
164 words
A method for transporting a SONET/SDH formatted
asynchronous transfer mode (ATM) signal on a unidirectional line
switched ring comprising the steps of: connecting a plurality (K) of nodes in a ring network provided
with a working transmission line associated with a first direction of
transmission and a protection transmission line associated with a
second direction of transmission, opposite to said first direction; detecting at a node (k) an error signal received from a node (k-1)
located adjacent to said node (k) and upstream with respect to said first
direction; at said node (k), generating a status change request upon receipt
of said error signal, and transmitting said status change request on said
working and protection transmission line; and restructuring all said nodes of said ring to operate according to
one of a working transmission line failure (WTLF), a node failure
(NF), a protection transmission line failure (PTLF), and a working and
protection transmission line failure (WPTLF) configuration, upon
receipt of said status change request.
Claim 8
Dependent Claim
32 words
A method as claimed in claim 7, further comprising the step
of restructuring all said nodes of said ring for operation in an idle state
upon receipt of a ring recovery request.
Claim 9
Dependent Claim
23 words
A method as claimed in claim 7, wherein said error signal
indicates one of a lost connection (SF) and a degraded connection (SD).
Claim 10
Dependent Claim
22 words
A method as claimed in claim 8, wherein said ATM traffic
comprises one of an STS-Mc and a plurality (M) of STS-1s.
Claim 11
Dependent Claim
36 words
A method as claimed in claim 10, wherein said error signal,
said status change request and ring recovery request signals are
transported around said ring in the K-bytes of the transport overhead
(TOH) of said STS-Mc.
Claim 12
Dependent Claim
51 words
A method as claimed in claim 7, wherein said step of
restructuring all nodes into said WTLF configuration comprises: remodelling said node (k) to assume a switched state; remodelling said node (k-1) to assume a bridged state; and remodelling all remaining nodes (p), where p≠k, k-1, to assume
a passthrough state.
Claim 13
Dependent Claim
100 words
A method as claimed in claim 12, wherein said node (k) in
said switched state performs the operations of: receiving an incoming ATM STS-Mc from said protection
transmission line; determining the address of a destination node (q) for said
incoming ATM STS-Mc, routing said incoming ATM STS-Mc from said protection
transmission line onto said working transmission line if said
destination node (q) is not said node (k); extracting said incoming ATM STS-Mc from said protection fiber
if said destination node (q) is said node (k); and inserting an outgoing STS-Mc originating at said node (k) into
said working transmission line.
Claim 14
Dependent Claim
103 words
A method as claimed in claim 12, wherein a node (p) in said
passthrough state performs the operations of: receiving an incoming ATM STS-Mc from said working
transmission line; determining the address of a destination node (q) for said
incoming ATM STS-Mc; extracting said incoming ATM STS-Mc from said working
transmission line, if said destination node (q) is same as said node (p); routing any traffic received on said protection transmission line
back onto said protection transmission line if said destination node (q)
is not said node (p); and inserting an outgoing STS-Mc originating at said node (p) onto
said working transmission line.
Claim 15
Dependent Claim
103 words
A method as claimed in claim 12, wherein said node (k-1) in
said bridges state performs the operations of: receiving an incoming ATM STS-Mc on said working
transmission line; determining the address of a destination node (q) for said
incoming ATM STS-Mc; extracting said incoming ATM STS-Mc from said working
transmission line if said destination node (q) is same as said node (k-1); routing said incoming ATM STS-Mc from said working
transmission line onto said protection transmission line if said
destination node (q) is not said node (k-1); and inserting an outgoing STS-Mc originating at said node (k-1) onto
said protection transmission line.
Claim 16
Dependent Claim
76 words
A method as claimed in claim 12, further comprising the
steps of: identifying at said node (k) if said status change request indicates
a NF error and determining the address of a failed node; receiving an incoming ATM STS-Mc and determining the
address of a destination node (q) for said incoming ATM STS-Mc; and discarding incoming ATM STS-Mc if the address of said
destination node (q) is the same as the address of said failed node.
Claim 17
Independent Claim
220 words
A method for communicating information on a
bidirectional line switched ring (BLSR) configuration including a
plurality (K) of ring nodes connected by a first and a second
transmission line, comprising the steps of: deploying said BLSR in a homing-type configuration, each node
(k) having an incoming path associated with a node drop direction and
an outgoing path associated with a node add direction: at a first node (q), where q≠k, of said BLSR, transmitting a first
SONET/SDH formatted signal along said first transmission line, said
first SONET/SDH formatted signal having a bandwidth K×BW; at each node (k), where k≠q, of said BLSR, receiving said first
SONET/SDH formatted signal from said first transmission line,
extracting same over a respective incoming path, and re-transmitting
said first SONET/SDH formatted signal over a respective outgoing path
back into said first transmission line; at each said node (k), inserting a respective outgoing
SONET/SDH formatted signal into said second transmission line over
said respective outgoing path, each outgoing SONET/SDH formatted
signal comprising traffic formatted at a respective node (k), and having
a bandwidth BW; and at each said node (k), extracting a respective incoming
SONET/SDH formatted signal received from said second transmission
line over said respective incoming path, each incoming SONET/SDH
formatted signal comprising traffic addressed to said respective node
(k), and having said bandwidth BW.
Claim 18
Dependent Claim
150 words
A node for a SONET/SDH line switched ring comprising: a first ring interface with a first working port for receiving an
incoming optical signal OC-Mc from a working transmission line
associated with a first direction of transmission, and converting same
into an incoming STS-Mc; a second ring interface with a second working port for
converting an outgoing STS-Mc into an outgoing optical signal OC-Mc
and transmitting same over said working fiber; an ATM cell management block for routing an output ATM cell
extracted from said incoming STS-Mc as one of a drop ATM cell and a
passthrough ATM cell, and multiplexing said passthrough ATM cell
and an add ATM cell into said outgoing STS-Mc; and an STS management block for routing said incoming STS-Mc
between said first ring interface and said ATM cell management block,
and said outgoing STS-Mc between said ATM cell management block
and said second ring interface.
Claim 19
Dependent Claim
98 words
A node as claimed in claim 18, further comprising: a first protection port at said second interface, connected to a
protection transmission line associated with a second direction of
transmission opposed to said first direction of transmission; a second protection port at said first interface connected to said
protection transmission line; and an STS protection controller for detecting an error signal in said
incoming STS-Mc and instructing said STS management block to
configure said first and second ring interfaces to route said incoming
STS-Mc and said outgoing STS-Mc in conformity with a unidirectional
line switched protection protocol (ULSPP).
Claim 20
Dependent Claim
150 words
A node as claimed in claim 18, wherein said ATM cell
management unit comprises: a STS management interface for receiving said incoming ATM
signal and delineating therefrom said drop and said passthrough ATM
cells and for receiving said add ATM cell and multiplexing same into
said outgoing ATM signal; a cell control unit for routing said add, drop and passthrough
ATM cells to one of said ATM trib interface and said STS management
interface, according to a respective virtual path identifier (VPI); an ATM trib interface for receiving said drop ATM cell and
routing same to an ATM trib port, and for receiving said add cell from
said ATM trib port and routing same to said cell control unit; a first routing table for storing the VPI of said drop ATM cell and
passthrough ATM cell; and a second routing table for storing the VPI of said add ATM cell.
Claim 21
Dependent Claim
223 words
A node for a SONET/SDH line switched ring comprising: a first ring interface with a first working port for receiving a
SONET/SDH formatted incoming optical signal from a working
transmission line associated with a first direction of transmission, and
converting same into an incoming non-ATM signal and an incoming
ATM signal; a second ring interface with a second working port for
converting an outgoing non-ATM signal and an outgoing ATM signal
into an outgoing SONET/SDH formatted optical signal and
transmitting same over said working transmission line; an ATM cell management block for processing and transmitting
an output ATM cell extracted from said incoming ATM signal as one of
a drop ATM cell and a passthrough ATM cell, and multiplexing said
passthrough ATM cell and an add ATM cell into said outgoing ATM
signal; an STS management block for routing said incoming non-ATM
signals as one of an output non-ATM signal and a passthrough non-ATM
signal, routing said passthrough non-ATM signal and an input
non-ATM signal as said outgoing non-ATM signal and routing said
incoming and outgoing ATM signals between said first and said second
ring interfaces and said ATM cell management block; and a non-ATM payload management for processing and
transmitting said output non-ATM signal to a non-ATM port, and for
processing and transmitting said outgoing non-ATM signal to said STS
management block.
Claim 22
Dependent Claim
167 words
A node as claimed in claim 21, further comprising: a first protection port at said second interface, connected to a
protection transmission line associated with a second direction of
transmission opposed to said first direction of transmission; a second protection port at said first interface connected to said
protection transmission line; an STS protection controller for detecting an error signal in said
incoming ATM signal and said incoming non-ARTM signal, and for
instructing said STS management block to configure said first and
second interfaces to route said incoming and said outgoing ATM
signals in conformity with a unidirectional line switched protection
protocol (ULSPP), and to route said incoming and outgoing non-ATM
signals in conformity with an unidirectional path switched protection
protocol (UPSPP); and a non-ATM protection controller for detecting a further error
signal in said output and input non-ATM signals and instructing said
non-ATM payload management to route said output and input non-ATM
signals between said STS management block and said non-ATM
port according to said UPSPP.
References Cited (Backward Citations)
No citation records indexed.
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