Patent Application
20150055947
The invention disclosed herein generally relates to a Wavelength Division Multiplexed (WDM) optical network, and more particularly relates to optical port discovery in WDM optical networks.
Conventional approaches to transporting mobile, business, and residential service traffic have dedicated different parallel networks to transporting the traffic of different services. More recent approaches, by contrast, contemplate transporting the traffic of those different services together using the same network. Converging the different parallel networks into one common network in this way would prove more efficient and cost-effective.
Aggregating the traffic of multiple services at the packet level through so-called packet aggregation presents one option for realizing such a “converged” network. But while packet aggregation currently requires less hardware expense, it proves difficult to scale as traffic volume increases and involves significant complexity. Aggregating the traffic of multiple services in the optical domain, e.g., using wavelength division multiplexing (WDM), is more promising in this regard. However, one obstacle to realizing a converged WDM optical network is optical port discovery due to the limited capability of logic processing on optical signals.
One conventional solution achieves optical port discovery by iteratively subdividing, in a bifurcated fashion, a spectrum of unallocated wavelength channels, to simplify the search process associated with discovering the wavelength channel of a newly deployed optical port. Such iterative bifurcation processes, however, may take an undesirable amount of time.
The solution presented herein reduces the time required for optical port discovery by using an overhead message in an optical signal received at a hub node that explicitly identifies a new wavelength channel associated with a new optical port at a remote node, e.g., a client node or a service-side node.
A hub node in a wavelength division multiplexed (WDM) optical network according to one exemplary embodiment is configured to identify a new wavelength channel associated with a new optical port at a remote node. The hub node comprises a port discovery circuit and a wavelength controller. The port discovery circuit is configured to discover the new optical port and the associated new wavelength channel. To that end, the port discovery circuit comprises at least one receiver configured to receive an optical signal from the remote node, wherein the optical signal includes an overhead message identifying the new wavelength channel associated with the new optical port, and where the receiver includes a search controller configured to identify which of a plurality of unallocated wavelength channels comprises the new wavelength channel based on the overhead message. The wavelength controller, which is configured to associate wavelength channels with the corresponding optical ports, comprises a receiver and an allocation circuit. The receiver is configured to receive an indication of the new wavelength channel from the port discovery circuit. The allocation circuit is configured to associate the new wavelength channel with the new optical port.
An exemplary method, executed in a hub node of a wavelength division multiplexed (WDM) optical network, identifies a new wavelength channel associated with a new optical port at a remote node. The method comprises receiving an optical signal from the remote node, the optical signal including an overhead message identifying the new wavelength channel associated with the new optical port. The method further includes identifying which of a plurality of unallocated wavelength channels comprises the new wavelength channel based on the overhead message, and associating the new wavelength channel with the new optical port.
An exemplary remote node is configured for connection to a hub node in a wavelength division multiplexed (WDM) optical network 10, where the remote node comprises a packet header circuit and an optical port. The packet header circuit is configured to write wavelength information associated with a requested wavelength channel of the WDM optical network into an overhead message of packet carried by an optical signal. The optical port is configured to send the optical signal including the overhead message to the hub node to explicitly identify the requested wavelength channel to the hub node.
An exemplary method, executed in a remote node configured for connection to a hub node in a wavelength division multiplexed (WDM) optical network, comprises writing wavelength information associated with a requested wavelength channel of the WDM optical network into an overhead message of an optical signal. The method further comprises sending the optical signal including the overhead message to the hub node from an optical port of the remote node to explicitly identify the requested wavelength channel to the hub node.
In general, each access sub-network node 16 communicatively connects to one or more client nodes 20, e.g., a remote radio unit, a base station, a wireless access point, or the like. Deployed at each client node 20 are one or more optical port modules that provide one or more optical ports. In some embodiments, for example, an optical port module is a hot-pluggable or hot-swappable module that is deployed at a client node 20 by being physically plugged into that client node 20. Examples of such a pluggable module include, but are not limited to, a small form-factor pluggable (SFP) transceiver module, an XFP transceiver module, etc.
Communicatively connected to one or more of the clients nodes 20, an access sub-network node 16 aggregates the wavelength channels on which those client nodes 20 transmit uplink traffic and places (i.e., adds) the aggregated wavelength channels onto the access sub-network 14 it forms. Similarly, the access sub-network node 16 drops from the access sub-network 14 the wavelength channels on which downlink traffic is transmitted to those client nodes 20. An access sub-network node 16 may therefore be appropriately referred to as an access add-drop (AAD) point.
The access network 12 in turn connects to a higher-tiered network, e.g., a metro network 22 at tier 2. The metro network 20 is formed from a plurality of interconnected central offices (COs) 24. Each CO 24 aggregates wavelength channels from one or more access sub-networks 14 to which it is connected such that the aggregated wavelength channels are “hubbed” to a hub node 100 in the metro network 22.
The hub node 100 in turn routes wavelength channels from one or more COs 24 to a higher-tiered network called the regional network 26. More specifically, the hub node 100 routes wavelength channels to an appropriate one of multiple service-side nodes (not shown), e.g., a business services edge router, a residential services or mobile services broadband network gateway (BNG), a broadband remote access server (BRAS), etc. The service-side node then routes uplink traffic from the wavelength channels (typically at the packet level) towards an appropriate destination, such as to content servicers, back towards the access networks, to the Internet, etc. Such service-side node routing may entail sending the uplink traffic to the regional network, which operates back at the optical layer. Thus, although omitted from
The regional network 26 is also formed from a plurality of interconnected peer network nodes, which place the uplink traffic onto a long haul network 28 at tier 4, for inter-regional transport. Downlink traffic propagates through the networks in an analogous, but opposite, manner.
Any given client-side optical port 30 optically transmits and receives traffic for a particular type of service (e.g., mobile, business, or residential). Moreover, predetermined attributes define how any given client-side optical port 30 transmits and receives such traffic, e.g., at a particular nominal data rate (e.g., 1 Gigabit, 10 Gigabits, 2.5 Gigabits, etc.) using a particular physical layer protocol (e.g., Ethernet, Common Public Radio Interface, etc.) and a particular line code (e.g., Carrier-Suppressed Return-to-Zero, Alternate-Phase Return-to-Zero, etc.). This means the uplink traffic transmitted by a given client-side optical port 30 must ultimately be routed to a service-side optical port 33 that has matching attributes in the sense that the service-side optical port 33 supports the particular type of service to which the uplink traffic pertains, supports the particular service provider providing that type of service, supports the particular physical layer protocol and line code with which the uplink traffic is transmitted, and the like. A client-side optical port 30 and a service-side optical port 33 that match in this sense are referred to herein as a matching pair of optical ports 30, 33. Conversely, the downlink traffic from a service-side port 33 must ultimately be routed to a client-side port 30 that matches in an analogous sense.
The hub node 100 in
The methods 300, 400 of
At the hub node 100, the port discovery circuit 110 searches for a new optical port 220, i.e., a port 220 newly deployed at the corresponding remote node 200. When port discovery circuit 110 detects the presence of an optical signal, the port discovery circuit 110 determines that an optical port 220 has been newly deployed at a remote node 200 to transmit or receive on a previously unallocated wavelength channel. In response, the port discovery circuit 110 reads the overhead message in the received optical signal to identify the wavelength channel requested for the newly deployed port 220, and notifies the wavelength controller 120 of the identified wavelength channel via signaling line 106. In addition, the port discovery circuit 110 also discovers the attributes associated with the optical port 220 and sends the discovered attributes to the wavelength controller 120, e.g., via signaling line 106. Port discovery circuit 110 may also notify the wavelength selection circuit 130 of the identified wavelength channel, e.g., via signaling line 104.
Wavelength controller 120 associates the identified wavelength channel with the newly deployed optical port 220, and indicates this association to the wavelength selection circuit 130, e.g., via signaling line 108. The wavelength selection circuit 130 routes the wavelength channels to the port discovery circuit 110 or between matching pairs of optical ports 30, 33 as controlled by the wavelength controller 120.
As noted above, each circuit in the hub node 100 performs a specific function towards the identification and rerouting of the new wavelength channel. For example, the port discovery circuit 110 identifies which of the plurality of unallocated wavelength channels comprises the new wavelength channel based on the overhead message, while the wavelength controller 120 associates the new wavelength channel with the newly deployed optical port, and the wavelength selection circuit 130 routes unallocated wavelength channels to the port discovery circuit 110 and reroutes allocated wavelength channel(s) between matching pairs of optical port(s) 220. The following discusses each circuit in detail as each circuit relates to the solution disclosed herein. For simplicity, many operational details associated with each circuit that are irrelevant to the solution disclosed herein are excluded from this discussion.
The discovery circuit 116 discovers one or more attributes of the optical port 220 from the optical signal using any known techniques. The attributes collectively describe or characterize the newly deployed port 220 in terms the capabilities, configuration, and/or use of the port 220. In one or more embodiments, the predefined set of attributes of a new port 220 includes a physical layer protocol used by the port. Additionally or alternatively, the predefined set of attributes of an optical port 220 includes a nominal data rate supported by the optical port 220, a type of service supported by the optical port 220, a line code used by the optical port 220, and/or an error protection (e.g., detecting and/or correcting) code used by the optical port 220. In yet other embodiments, the predefined set of attributes of an optical port 220 additionally or alternatively include a vendor of the remote node 200 at which the optical port 220 is deployed and/or a provider of the service supported by the optical port 220. The port discovery circuit 110 provides the wavelength channel information and the identified attributes associated with the newly deployed optical port 220 to the wavelength controller 120 via, e.g., a reporting circuit 118, on signaling line 106.
Upon identifying a matching pair of client-side and service-side optical ports 30, 33, the wavelength controller 120 dynamically controls the wavelength selection circuit 130 to appropriately route the wavelength channels. The wavelength controller 120 may directly control a wavelength selection circuit 130 that is part of the hub node 100 via signaling line 108 as shown in
Consider a simple example shown in the context of
Assume now that optical port 33A is newly deployed at service-side node 32A (e.g., by being plugged into that node 32A). Upon such deployment, port 33A begins to transmit an optical signal over CH3. Responsive to detecting the presence of the optical signal on CH3, search controller 114 reads the overhead message in the received optical signal to identify the new wavelength channel, e.g., CH3, associated with the new optical port 33A. Discovery circuit 116 discovers a predefined set of one or more attributes of port 33A by inspecting the optical signal. For example, this discovered set of attributes may include the port being a broadband network gateway (BNG) port that supports a 1 Gigabit data rate for a fixed residential broadband service provided by service provider Y. Responsive to such discovery, the wavelength controller 120 searches for a client-side optical port 30 that has a matching set of attributes. If no such match exists yet, the wavelength controller 120 stores or otherwise remembers the discovered set of attributes for subsequent matching determinations.
Now assume, optical port 30A is later newly deployed at client node 20A (e.g., by being plugged into that client node 20A). Upon such deployment, port 30A begins to transmit an optical signal over CH3. Responsive to detecting the presence of the optical signal on CH3, the search controller 114 reads the overhead message in the optical signal to identify the new wavelength channel, e.g., CH3, associated with the new optical port 30A, and discovery circuit 116 discovers a predefined set of one or more attributes of port 30A by inspecting that optical signal. For example, this predefined set of attributes of port 30A may include the port being a digital subscriber line access multiplexer (DSLAM) port that supports a 1 Gigabit data rate for a fixed residential broadband service provided by service provider Y. Responsive to such discovery, the wavelength controller 120 searches for a service-side optical port 33 that has a matching set of attributes. The allocation circuit 124 in the wavelength controller 120 determines in this regard that client-side port 30A and service-side port 33A form a matching pair, because their discovered sets of attributes match. Indeed, the ports 30A, 33A support the same data rate for the same type of service and for the same service provider, are compatible in terms of being a DSLAM port and a BNG port, etc. The allocation circuit 124 therefore controls the wavelength selection circuit 130, and thus the routing circuit 132, to re-route CH3 from the port discovery circuit 110 between ports 30A and 33A.
In some exemplary embodiments, port discovery circuit 110 includes a test circuit 119 configured to perform a transmission test for the wavelength channel identified by the overhead message, as shown in
In some exemplary embodiments, the wavelength selection circuit 130 also includes a subdivision circuit 134 to handle scenarios where more than one optical signal is received by the hub node 100, e.g., from more than one newly deployed optical port 220. The receiver 112 in port discovery circuit 110 may determine that multiple optical signals have been received based on a received power level, a decoding error, etc. For example, receiver 112 may determine that an optical signal is present when the received power level exceeds a first threshold, and may determine that multiple optical signals are present when the received power level exceeds a second threshold greater than the first threshold.
When the receiver 112 detects an optical power variation, the receiver 112 knows there is an optical signal present on at least one of the unallocated wavelength channels. The process discussed above discloses how the hub node 100 identifies the wavelength channel associated with the optical signal when there is only one optical signal. If there is more than one optical signal, the multiple optical signals interfere with each other, making it difficult if not impossible for the hub node 100 to read the overhead messages containing the explicit wavelength channel information. To address such situations, the wavelength selection circuit 130 may include a subdivision circuit 134, as shown in
For example, assume there are eight unallocated wavelength channels (e.g., CH1-CH8), and that an optical signal is present on each of CH3 and CH6. After the receiver 112 determines there is more than one optical signal present, subdivision circuit 134 bifurcates the original group of four unallocated wavelength channels into two groups: Subgroup A containing CH1- and CH4, and Subgroup B containing CH5-CH8. The routing circuit 132 then routes the unallocated wavelength channels of Subgroup A to the port discovery circuit 110 while blocking the unallocated wavelength channels of Subgroup B. Because there is now only one optical signal present in Subgroup A, the search controller 114 is able to read the overhead message of the optical signal in Subgroup A and identify the wavelength channel, e.g., CH3, as disclosed herein. Subsequently, routing circuit 132 routes the unallocated wavelength channels of Subgroup B to the port discovery circuit 110 while blocking the unallocated wavelength channels of Subgroup A. Because there is now only one optical signal present Subgroup B, the search controller 114 is able to read the overhead message of the optical signal in Subgroup B and identify the wavelength channel, e.g., CH6.
Consider another example where there are eight unallocated wavelength channels (e.g., CH1-CH8), and that an optical signal is present on each of CH1 and CH3. After the receiver 112 determines there is more than one optical signals present, the subdivision circuit 134 bifurcates the original group of four unallocated wavelength channels into two groups: Subgroup A containing CH1-CH4, and Subgroup B containing CH5-CH8. The routing circuit 132 then routes the unallocated wavelength channels of Subgroup A to the port discovery circuit 110 while blocking the unallocated wavelength channels of Subgroup B. Because there are still two optical signals present in Subgroup A, the search controller 114 still cannot read the overhead messages. Thus, the subdivision circuit 134 further bifurcates Subgroup A into Subgroup A1 containing CH1-CH2 and Subgroup A2 containing CH3-CH4. The routing circuit 132 then routes the unallocated wavelength channels of Subgroup A1 to the port discovery circuit 110 while blocking the unallocated wavelength channels of Subgroups A1 and B. Because there is now only one optical signal present in Subgroup A1, the search controller 114 is able to read the overhead message of the optical signal in Subgroup A1 and identify the wavelength channel, e.g., CH1, as disclosed herein. Subsequently, routing circuit 132 routes the remaining unallocated wavelength channels of Subgroups A2 and B to the port discovery circuit 110. Because there is now only one optical signal present in the unallocated wavelength channels, the search controller 114 is able to read the overhead message of the optical signal in Subgroup A2 and identify the wavelength channel, e.g., CH3, as disclosed herein.
The solution disclosed herein substantially reduces the total time required to reroute wavelength channels between newly deployed optical port(s). For example, when only one optical signal is present, the wavelength selection circuit 130 can block a wavelength channel associated with a newly deployed optical port 220 receiving new optical signals associated with other optical ports within 100 ms of the hub circuit 100 determining the new optical port 220 has been deployed. This is a savings of 100 mx per cycle relative to prior art solutions. When multiple optical signals, the wavelength selection circuit 130 only needs three configuration cycles, each of which are 100 ms long, to locate CH1, for example. Consider the example where a finely tuned laser provides 100 possible wavelength channels, e.g., spaced by 25 GHz. In this case, the solution disclosed herein can reduce the average time needed to discover the wavelength channel of a newly deployed optical port to 1 second, which is a significant improvement over the 400 seconds required on average for some prior art solutions.
Various elements of the hub node 100 and remote node 200 disclosed herein are described as some kind of circuit. Each of these circuits may be embodied in hardware and/or in software (including firmware, resident software, microcode, etc.) executed on a controller or processor, including an application specific integrated circuit (ASIC).
It is possible that there are services carried other than Ethernet in MetNet, e.g., OTN or CPRI. In this case, the remote node 200 will write the wavelength information in an overhead message of a packet according to the underlying protocol, and the port discovery circuit 110 should be enhanced by adding modules that are able to read the corresponding overhead messages.
The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.
