US 7,120,360 B2Granted

System and method for protecting traffic in a hubbed optical ring network

AssigneeFujitsu Limited

InventorsCechan Tian, Susumu Kinoshita

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Abstract

An optical access network includes a first ring and a second ring communicating optical signals in opposite directions. The network also includes an access node coupled to both rings that adds traffic in a first wavelength of a first optical signal communicated on the first ring. Furthermore, the network includes a hub node coupled to each ring and coupled to an optical core network. The hub node receives the first optical signal, forwards a first copy of the signal to a first wavelength blocking unit that terminates the traffic in the first wavelength, and forwards a second copy of the signal to a first network interconnection element that forwards the traffic in the first wavelength to the core network. Furthermore, upon detection of an interruption of the traffic in the first wavelength on the first ring, the access node adds the traffic in a second wavelength of a second optical signal communicated on the second ring. In addition, the hub node receives the second optical signal, forwards a first copy of the signal to a second wavelength blocking unit that terminates the traffic in the second wavelength, and forwards a second copy of the signal to a second network interconnection element that forwards the traffic in the second wavelength to the core network.

Claims17

Dependent claims

An optical access network, comprising:

a first ring operable to communicate optical signals in a first direction and a second ring operable to communicate optical signals in a second, opposite direction;
one or more access nodes coupled to each ring and operable to passively add and drop traffic to and from each ring in one or more wavelengths, wherein at least a first access node is operable to add traffic in at least a first wavelength of a first optical signal communicated on the first ring;
a hub node coupled to each ring and also coupled to an optical core network, the hub node comprising one or more components configured to:
receive the first optical signal on the first ring;
forward a first copy of the first optical signal to a first wavelength blocking unit of the hub node associated with the first ring, the first wavelength blocking unit configured to selectively forward or terminate the traffic in each wavelength of the first optical signal, wherein the traffic in the first wavelength is terminated;
and
forward a second copy of the first optical signal to a first network interconnection element of the hub node associated with the first ring, the first network interconnection element configured to selectively forward to the core network or terminate the traffic in each wavelength of the first optical signal, wherein the traffic in the first wavelength is forwarded to the core network;
the first access node comprising logic embodied on a computer-readable medium and operable to configure the first access node upon detection of an interruption of the traffic in the first wavelength on the first ring to add the traffic in a second wavelength of a second optical signal communicated on the second ring;
and
the hub node comprising logic embodied on a computer-readable medium and operable to configure the hub node upon detection of an interruption to:
receive the second optical signal on the second ring;
forward a first copy of the second optical signal to a second wavelength blocking unit of the hub node associated with the second ring, wherein the traffic in the second wavelength is terminated;
and
forward a second copy of the second optical signal to a second network interconnection element of the hub node associated with the second ring, wherein the traffic in the second wavelength is forwarded to the core network.

11 more elements

A method for protecting traffic in an optical access network having a first ring and a second ring carrying optical signals in opposite directions, the network comprising a plurality of access nodes coupled to each ring and operable to passively add and drop traffic to and from each ring in one or more wavelengths, the network further comprising a hub node coupled to each ring and also coupled to an optical core network, the method comprising:

at a first access node, adding traffic in at least a first wavelength of a first optical signal communicated on the first ring;
at the hub node:
receiving the first optical signal on the first ring;
forwarding a first copy of the first optical signal to a first wavelength blocking unit of the hub node associated with the first ring that is operable to selectively forward or terminate the traffic in each wavelength of the first optical signal, wherein the traffic in the first wavelength is terminated;
and
forwarding a second copy of the first optical signal to a first network interconnection element of the hub node associated with the first ring that is operable to selectively forward to the core network or terminate the traffic in each wavelength of the first optical signal, wherein the traffic in the first wavelength is forwarded to the core network;
upon detection of an interruption of the traffic in the first wavelength on the first ring, adding the traffic in a second wavelength of a second optical signal communicated on the second ring at the first access node;
and
upon detection of the interruption, at the hub node:
receiving the second optical signal on the second ring;
forwarding a first copy of the second optical signal to a second wavelength blocking unit of the hub node associated with the second ring, wherein the traffic in the second wavelength is terminated;
and
forwarding a second copy of the second optical signal to a second network interconnection element of the hub node associated with the second ring, wherein the traffic in the second wavelength is forwarded to the core network, thereby protecting the traffic despite the interruption.

10 more elements

Dependencies are inferred from the claim text.