Optical subchannel routing, protection switching and security
View Patent ↗The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Tunable lasers are employed to generate subcarrier frequencies representing subchannels of an ITU channel to which client signals can be mapped. Client circuits can be divided and combined before being mapped, independent of one another, to individual subchannels within and across ITU channels. Subchannels may be independently routed to a single subchannel receiver filter, such that each subchannel detected at the receiver may come from a different source location. Network architectures and subchannel transponders, muxponders and crossponders are disclosed, and techniques are employed (at the subchannel level/layer), to facilitate the desired optical routing, switching, concatenation and protection of client circuits mapped to these subchannels across the nodes of a WDM network. Subchannel hopping may also be used to increase the optical network security.
1. A system that can route client signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the system comprising:
(a) a subchannel mapper that can map each of a plurality of client signals to any available subchannel of any ITU channel, wherein each ITU channel has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel's corresponding ITU channel;
(b) a first network route that designates the origin of a first client signal at a first node, and a destination for the first client signal at a second node; and
(c) a tunable laser at the first node that can be set to a first subchannel frequency for which the second node has a filter to receive signals transmitted at that subchannel frequency,
(d) whereby the system can route the client signal from the first node to the second node by tuning the laser to the first subchannel frequency and mapping the client signal to the subchannel associated with that subchannel frequency; and
(e) further comprising a software-controlled routing table that:
(i) assigns client signals to requested output ports at a desired destination node of the optical network;
(ii) assigns available subchannel frequencies to client signals based on the requested output port;
(iii) resolves potential conflicts in the assignment of client signals to output ports and available subchannel frequencies; and
(iv) communicates assignments of client signals, output ports and subchannel frequencies among the nodes of the optical network.
2. The system of claim 1 , wherein various information in the routing table can be displayed to network operators and other users of the optical network, the information including one or more of the following:
(a) the hardware availability, deployed status and current state of use of ITU channels and subchannels;
(b) one or more performance metrics of ITU channels and subchannels, including bit error rate (BER), power level, optical signal-noise ratio (OSNR), chromatic dispersion (CD), and polarization-mode dispersion (PMD), as well as nonlinear fiber penalties such as cross-phase modulation and four-wave mixing;
(c) node status, including whether a node will add, drop or passthrough a particular client signal; and
(d) an overall map illustrating ITU channel and subchannel connections.
3. A method for routing client signals among a plurality of nodes interconnected by one or more fiber optic cables to form an optical network, the method comprising the following steps:
(a) mapping each of a plurality of client signals to any available subchannel of any ITU channel, wherein each ITU channel has a predefined ITU frequency and a corresponding plurality of subchannels, and wherein each subchannel has an associated frequency with a predetermined offset from the predefined ITU frequency of the subchannel's corresponding ITU channel;
(b) designating the origin of a first client signal at a first node, and a destination for the first client signal at a second node; and
(c) setting a tunable laser at the first node to a first subchannel frequency for which the second node has a filter to receive signals transmitted at that subchannel frequency,
(d) whereby the client signal can be routed from the first node to the second node by tuning the laser to the first subchannel frequency and mapping the client signal to the subchannel associated with that subchannel frequency, and further comprising the steps of:
(i) assigning client signals to requested output ports at a desired destination node of the optical network;
(ii) assigning available subchannel frequencies to client signals based on the requested output port;
(iii) resolving potential conflicts in the assignment of client signals to output ports and available subchannel frequencies; and
(iv) communicating assignments of client signals, output ports and subchannel frequencies among the nodes of the optical network.
4. The method of claim 3 , wherein various information can be displayed to network operators and other users of the optical network, the information including one or more of the following:
(a) the hardware availability, deployed status and current state of use of ITU channels and subchannels;
(b) one or more performance metrics of ITU channels and subchannels, including bit error rate (BER), power level, optical signal-noise ratio (OSNR), chromatic dispersion (CD), and polarization-mode dispersion (PMD), as well as nonlinear fiber penalties such as cross-phase modulation and four-wave mixing;
(c) node status, including whether a node will add, drop or passthrough a particular client signal; and
(d) an overall map illustrating ITU channel and subchannel connections.