EP0920153A2
Expired / Lapsed
EP
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Ring network for sharing protection resource by working communications paths
Assignee: NEC Corp
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Filing: 1998-11-30
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Granted: —
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Expires: 2018-11-30
Abstract
Abstract In a ring topology network, a number of nodes interconnect transmission links to form first and second working rings and first and second optical protection rings in a ring topology. Multiple working paths are established on each working ring and multiple protection paths are established on each protection ring corresponding to the working paths. A first working path spans across first and second nodes for transmission of a signal in a first direction of the ring topology, and a second working path of the second working ring spans across the first and second nodes for transmission of a signal in a second direction of the ring topology opposite to the first direction A first protection path on the first protection ring spans across the first and second nodes for transmission of a signal in the second direction of the ring topology, and a second protection path of the second protection ring spans across the first and second nodes for transmission of a signal in the first direction of the ring topology. The first and second nodes normally use the first and second working paths, respectively. Responsive to a failure of one of the first and second working paths, the first and second nodes use a corresponding one of the first and second protection paths, instead of the failed working path.
Inventors
- 👤 Tatsuya Shiragaki
- 👤 Naoya Henmi
- 👤 Makoto Nishio
- 👤 Hitoshi Takeshita
- 👤 Hirofumi Shimomura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 11:24
CPC Classifications
H; H04; H04J; H04J14/00; H04J14/02; H04J14/0278; H04J14/0283; H04J14/0287; H04J14/0293; H04J14/0295; H04J14/0297; H04J14/0201; H04J14/0202; H04J14/0206
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
152 words
A communications network comprising: a plurality of transmission links; and a plurality of nodes for interconnecting said links to form a working
ring and a protection ring in a ring topology, and establishing a plurality of
working paths on said working ring and a plurality of protection paths on
said protection ring corresponding to said plurality of working paths, one of said working paths spanning across first and second nodes of
said plurality of nodes for transmission of a signal in a first direction of said
ring topology, one of said protection paths spanning across said first and second
nodes for transmission of a signal in a second direction of said ring
topology opposite to said first direction, said first and second nodes normally using said one working path
and being responsive to a failure of said one working path for using said
one protection path instead of said one working path.
Claim 2
Dependent Claim
252 words
A communications network comprising: a plurality of transmission links; and a plurality of nodes for interconnecting said transmission links to
form first and second working rings and first and second protection rings
in a ring topology, and establishing a plurality of working paths on each of
said working rings and a plurality of protection paths on each of said
protection rings corresponding to said plurality of working paths, a first one of said working paths of said first working ring spanning
across first and second nodes of said plurality of nodes for transmission of
a signal in a first direction of said ring topology, a second one of said working paths of said second working ring
spanning across the first and second nodes for transmission of a signal in a
second direction of the ring topology opposite to the first direction, a first one of said protection paths on said first protection ring
spanning across the first and second nodes for transmission of a signal in
said second direction of said ring topology, a second one of said protection paths of said second protection ring
spanning across the first and second nodes for transmission of a signal in
said first direction of said ring topology, said first and second nodes normally using said first and second
working paths, respectively, and being responsive to a failure of one of said
first and second working paths for using a corresponding one of the first
and second protection paths instead of the failed working path.
Claim 3
Dependent Claim
200 words
A communications network comprising: a plurality of transmission links; and a plurality of nodes for interconnecting said links to form a working
ring and a protection ring in a ring topology, and establishing a plurality of
working paths on said working ring and a plurality of extra traffic paths on
said protection ring, one of said working paths spanning across first and second nodes of
said plurality of nodes for transmission of a signal in a first direction of said
ring topology, one of said extra traffic paths spanning across said first and second
nodes for transmission of a low-priority signal in a second direction of said
ring topology opposite to said first direction, said first and second nodes normally using said one working path
and being responsive to a failure of said one working path for clearing said
one extra traffic path to establish a first protection path and using the first
protection path, clearing other extra traffic paths to establish a second
protection path if said first protection path is not successfully established
and using said second protection path instead of the failed working path,
said first protection path having a shorter length than said second
protection path.
Claim 4
Dependent Claim
136 words
A communications network as claimed in claim 2, wherein first
and second working paths of said plurality of working paths are assigned a
first network resource and first and second protection paths of said
plurality of protection paths are assigned a second network resource, said first node normally using said first network resource and said
first working path and being responsive to a failure in said first ring for
using said second network resource and said second protection path
instead of said first network resource and said first working path, said second node normally using said second network resource and
said second working path and being responsive to a failure of the second
ring for using said first network resource and said first protection path
instead of the second network resource and the second working path.
Claim 5
Dependent Claim
121 words
A communications network as claimed in claim 2, wherein first
and second working paths of said plurality of working paths are assigned
first and second network resources, respectively, and first and second
protection paths of said plurality of protection paths are assigned said
second and first network resources, respectively, said first node normally using said first network resource and said
first working path and being responsive to a failure of said first ring for
using said second protection path instead of said first working path, said second node normally using said second network resource and
said second working path and being responsive to a failure of the second
ring for using the first protection path instead of the second protection path.
Claim 6
Dependent Claim
23 words
A communications network as claimed in claim 4 or 5, wherein
said first and second network resources are optical energy of different
wavelengths.
Claim 7
Dependent Claim
49 words
A communications network as claimed in claim 1, 2, 3, 4 or 5,
wherein said first node is arranged to detect said failure and transmit a
command signal to said second node for instructing the second node to
switch from said one working path to said one protection path.
Claim 8
Dependent Claim
16 words
A communications network as claimed in claim 7, wherein said
first node is a destination node.
Claim 9
Dependent Claim
22 words
A communications network as claimed in claim 7, wherein said
command signal is transmitted in format in which bit positions represent
information.
Claim 10
Dependent Claim
214 words
A communications network as claimed in claim 1, 2, 3, 4 or 5,
wherein each of said first and second nodes comprises: a first demultiplexer for receiving a multiplex signal from said one
working path for producing drop-off signals; a first multiplexer for multiplexing add-up signals onto said one
working path; a first path switch connected between said first demultiplexer and
said first multiplexer; a second demultiplexer for receiving a multiplex signal from said
one protection path for producing drop-off signals; a second multiplexer for multiplexing add-up signals onto said one
protection path; a second path switch connected between said second demultiplexer
and said second multiplexer; a transmit protection switch; a receive protection switch; and control circuitry for monitoring said one working path and
controlling said transmit protection switch so that one of said add-up
signals is coupled to said first multiplexer when no failure is detected in
said one working path and coupled to said second multiplexer when a
failure is detected in said one working path, and controlling said receive
protection switch so that one of said drop-off signals of said first
multiplexer is received when no failure is detected in said one working
path and one of said drop-off signals of said second multiplexer is received
when said failure is detected.
Claim 11
Dependent Claim
29 words
A communications network as claimed in claim 10, wherein
said control circuitry is arranged to exchange control signals with adjacent
nodes for controlling said transmit and receive protection switches.
Claim 12
Dependent Claim
32 words
A communications network as claimed in claim 10, wherein
each of said first and second demultiplexers comprises an optical
demultiplexer and each of said first and second multiplexers comprises an
optical multiplexer.
Claim 13
Dependent Claim
157 words
A communications network as claimed in claim 10, wherein
said transmit protection switch includes first and second output ports
associated with ones of said working paths and third and fourth output
ports associated with ones of said protection paths, said transmit protection switch being responsive to a control signal
from said control circuitry for coupling two add-up signals to said first and
second output ports respectively and coupling each one of said two add-up
signals to one of the third and fourth ports, wherein said receive protection switch includes first and second
input ports associated with ones of said working paths and third and fourth
input ports associated with ones of said protection paths, said receive protection switch being responsive to a control signal
from said control circuitry for receiving two drop-off signals from said first
and second input ports and receiving each one of the drop-off signals from
one of the third and fourth input ports.
Claim 14
Dependent Claim
103 words
A communications network as claimed in claim 11, wherein
said transmit protection switch comprises: first, second, third and fourth optical couplers respectively
connected to said first, second, third and fourth output ports; and first, second, third and fourth optical switches, said first optical
switch having outputs respectively coupled to said first, third and fourth
optical couplers, said second optical switch having outputs respectively
coupled to said second, third and fourth optical couplers, said third optical
switch having outputs coupled respectively to said first and third optical
couplers, and said fourth optical switching having outputs respectively
coupled to said second and fourth optical couplers.
Claim 15
Dependent Claim
103 words
A communications network as claimed in claim 11, wherein
said receive protection switch comprises: first, second, third and fourth optical couplers respectively
connected to said first, second, third and fourth input ports; and first, second, third and fourth optical switches, said first optical
switch having inputs respectively coupled to said first, third and fourth
optical couplers, said second optical switch having inputs respectively
coupled to said second, third and fourth optical couplers, said third optical
switch having inputs coupled respectively to said first and third optical
couplers, and said fourth optical switching having inputs respectively
coupled to said second and fourth optical couplers.
Claim 16
Dependent Claim
46 words
A communications network as claimed in claim 14, wherein
said transmit protection switch further comprises: a fifth optical coupler having outputs respectively connected to
said first and third optical switches; and a sixth optical coupler having outputs respectively connected to
said second and fourth optical switches.
Claim 17
Dependent Claim
46 words
A communications network as claimed in claim 15, wherein
said receive protection switch further comprises: a fifth optical coupler having inputs respectively connected to said
first and third optical switches; and a sixth optical coupler having inputs respectively connected to said
second and fourth optical switches.
Claim 18
Dependent Claim
256 words
A network node for a ring topology network, the network
having first and second working rings and first and second optical
protection rings in a ring topology, and a plurality of working paths on
each of said working rings and a plurality of protection paths on each of
said protection rings corresponding to said plurality of working paths,
the network node comprising: a first demultiplexer for receiving a multiplex signal from one of the
working paths for producing drop-off signals; a first multiplexer for multiplexing add-up signals onto said one
working path; a first path switch connected between said first demultiplexer and
said first multiplexer; a second demultiplexer for receiving a multiplex signal from one of
said protection paths for producing drop-off signals; a second multiplexer for multiplexing add-up signals onto said one
protection path; a second path switch connected between said second demultiplexer
and said second multiplexer; a transmit protection switch; a receive protection switch; and control circuitry for monitoring said one working path and
controlling said transmit protection switch so that one of said add-up
signals is coupled to said first multiplexer when no failure is detected in
said one working path and coupled to said second multiplexer when a
failure is detected in said one working path, and controlling said receive
protection switch so that one of said drop-off signals of said first
multiplexer is received when no failure is detected in said one working
path and one of said drop-off signals of said second multiplexer is received
when said failure is detected.
Claim 19
Dependent Claim
29 words
A network node as claimed in claim 18, wherein said control
circuitry is arranged to exchange control signals with adjacent nodes for
controlling said transmit and receive protection switches.
Claim 20
Dependent Claim
32 words
A network node as claimed in claim 18, wherein each of said
first and second demultiplexers comprises an optical demultiplexer and
each of said first and second multiplexers comprises an optical multiplexer.
Claim 21
Dependent Claim
157 words
A network node as claimed in claim 18, wherein said
transmit protection switch includes first and second output ports associated
with ones of said working paths and third and fourth output ports
associated with ones of said protection paths, said transmit protection switch being responsive to a control signal
from said control circuitry for coupling two add-up signals to said first and
second output ports respectively and coupling each one of said two add-up
signals to one of the third and fourth ports, wherein said receive protection switch includes first and second
input ports associated with ones of said working paths and third and fourth
input ports associated with ones of said protection paths, said receive protection switch being responsive to a control signal
from said control circuitry for receiving two drop-off signals from said first
and second input ports and receiving each one of the drop-off signals from
one of the third and fourth input ports.
Claim 22
Dependent Claim
103 words
A network node as claimed in claim 21, wherein said
transmit protection switch comprises: first, second, third and fourth optical couplers respectively
connected to said first, second, third and fourth output ports; and first, second, third and fourth optical switches, said first optical
switch having outputs respectively coupled to said first, third and fourth
optical couplers, said second optical switch having outputs respectively
coupled to said second, third and fourth optical couplers, said third optical
switch having outputs coupled respectively to said first and third optical
couplers, and said fourth optical switching having outputs respectively
coupled to said second and fourth optical couplers.
Claim 23
Dependent Claim
103 words
A network node as claimed in claim 21, wherein said receive
protection switch comprises: first, second, third and fourth optical couplers respectively
connected to said first, second, third and fourth input ports; and first, second, third and fourth optical switches, said first optical
switch having inputs respectively coupled to said first, third and fourth
optical couplers, said second optical switch having inputs respectively
coupled to said second, third and fourth optical couplers, said third optical
switch having inputs coupled respectively to said first and third optical
couplers, and said fourth optical switching having inputs respectively
coupled to said second and fourth optical couplers.
Claim 24
Dependent Claim
46 words
A network node as claimed in claim 22, wherein said
transmit protection switch further comprises: a fifth optical coupler having outputs respectively connected to
said first and third optical switches; and a sixth optical coupler having outputs respectively connected to
said second and fourth optical switches.
Claim 25
Dependent Claim
46 words
A network node as claimed in claim 23, wherein said receive
protection switch further comprises: a fifth optical coupler having inputs respectively connected to said
first and third optical switches; and a sixth optical coupler having inputs respectively connected to said
second and fourth optical switches.
Claim 26
Dependent Claim
208 words
A fault recovery method for a communications network,
wherein the network comprises a plurality of transmission links, and a
plurality of nodes for interconnecting said links to form a working ring and
a protection ring in a ring topology, and establishing a plurality of working
paths on said working ring and a plurality of protection paths on said
protection ring corresponding to said plurality of working paths, the
method comprising the steps of: a) establishing one of said working paths between source and
destination nodes of said plurality of nodes for transmission of a signal in a
first direction of said ring topology and establishing one of said protection
paths between said source and destination nodes for transmission of a
signal in a second direction of said ring topology opposite to said first
direction; b) using said one working path for communication between said
source and destination nodes; c) monitoring said working path at said destination node; d) transmitting a switching command message from said
destination node to said source node if a failure is detected in said working
path; and e) using said one protection path for communication between
said source and destination nodes, instead of the failed working path, in
response to said switching command message.
Claim 27
Dependent Claim
240 words
A fault recovery method for a communications network,
wherein the network comprises a plurality of transmission links, and a
plurality of nodes for interconnecting said links to form a working ring and
a protection ring in a ring topology, and establishing a plurality of working
paths on said working ring and a plurality of extra traffic paths on said
protection ring, the method comprising the steps of: a) establishing one of said working paths between source and
destination nodes of said plurality of nodes for transmission of a signal in a
first direction of said ring topology and establishing one of said extra traffic
paths between said source and destination nodes for transmission of a low-priority
signal in a second direction of said ring topology opposite to said
first direction, b) normally using said one working path between said source
and destination nodes; c) monitoring said one working path at said destination node; d) clearing said one extra traffic path to establish a short-haul
protection path between said source and destination nodes when a failure
is detected in said one working path and using the short-haul protection
path, instead of the failed working path, between said source and
destination nodes; and e) clearing other extra traffic paths to establish a long-haul
protection path if said short-haul protection path is not successfully
established and using said long-haul protection path, instead of the failed
working path, between said source and destination nodes.
References Cited (Backward Citations)
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