WO2015082493A1

WO2015082493A1 - Mirrored passive optical access network

Info

Publication number: WO2015082493A1
Application number: PCT/EP2014/076297
Authority: WO
Inventors: David Payne; Marco Ruffini; Alan Hill; Seamas MCGETTRICK
Original assignee: College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin
Current assignee: College of the Holy and Undivided Trinity of Queen Elizabeth near Dublin
Priority date: 2013-12-02
Filing date: 2014-12-02
Publication date: 2015-06-11
Anticipated expiration: 2016-06-02
Also published as: GB2520766A; GB201321197D0

Abstract

A method of configuring a passive optical access network, and a network configured accordingly, are disclosed. At least a first optical line terminal is connected to a remote network node via a first optical channel. At least a second optical line terminal is connected to the remote network node via a second optical channel. A plurality of data packets communicated downstream by the at least first optical line terminal are received at the network node. The plurality of data packets is then communicated upstream to the at least second optical line terminal.

Description

MIRRORED PASSIVE OPTICAL ACCESS NETWORK

Field

[01 ] The invention relates to a passive optical access network (PON) configuration. More particularly, the invention relates to a new and improved configuration of network nodes in a PON network.

Background

[02] The number and capacity requirements of network applications keep increasing, resulting in aggregate user requirements that increasingly exceed the average capacity offered by Digital Subscriber Line (DSL) services. Most operators throughout the world are already upgrading, or at least currently planning, large-scale upgrades to their access network infrastructures, towards a fibre-based access system, optimally based on the Fibre-To-The-Premises (FTTP) model. Certain operators have opted for intermediate solutions such as the Fibre-To-The-Cabinet (FTTC) model, which still uses conventional copper- pair access, but with a much reduced range of typically 100 to 300 meters between the cabinet at which the optical fibre terminates and the user premises. It is expected that such intermediate solutions will eventually be replaced by FTTP.

[03] In the above context, point-to-point optical access networks architectures are also expected to be replaced with shared architectures, for instances point-to- multipoint fiber networks called Passive Optical Networks (PONs). A PON is a type of fiber-optic access network for telecommunications, wherein an optical fiber which extends from the or each Optical Line Terminal (OLT) located at a respective central office of a network service provider, is split by an intermediary optical splitter into multiple optical fibers, each connected to a respective optical network unit (ONU) or optical network terminal (ONT) located near end users. A PON is thus a point-to-multipoint network architecture, which advantageously reduces the number of fibers and central office equipment required by comparison with a point-to-point architecture. [04] It is therefore envisaged that such fundamental changes in both the physical transmission medium, i.e. from copper to optical fibre, and in the business models for the provision of broadband Internet services, will lead to substantially-different network architectures co-existing, all relying upon optical fibre and all requiring an amount of protection or redundancy for the network configuration.

[05] As the relation between access, metro and core networks is expected to change over time, existing risk protection mechanisms need to be adapted and new mechanisms devised and implemented. Currently, core links are protected by installing dedicated path-diverse fibre cables in the core, which is expensive and time-consuming. Example implementations are disclosed in EP 2 605 427; EP 2 224 624; EP 1 746 857; and WO201 1/126416. Moreover, there are no smart protection systems in known PON architectures, whereby a user is expected to implement protection against network outage by duplicating the access infrastructure, i.e. having two network terminations working in parallel, which increases hardware requirements, implementation costs and maintenance in proportion. Without equipment duplication, the protection time for PONs has been determined, through testing by the inventors, as particularly long, of the order of half a minute. By contrast, optimal protection times should be in the order of 50 to 200 milliseconds.

[06] Accordingly, the present invention provides a solution which exploits optical access fibre deployment, both for decreasing protection times and implementing an additional and redundant path belonging to a different Shared-

Risk-Link-Group (SRLG).

Summary

[07] The present invention provides a novel configuration, as set out in the appended claims, through which two network nodes can exchange messages by using the protection links of a Passive Optical Network (PON) architecture, in the place of, or in addition to, other core links which the nodes might have. [08] Accordingly, in a first aspect of the present invention, a method of configuring a passive optical access network is provided, which comprises the steps of connecting at least a first optical line terminal to a remote network node via a first optical channel; connecting at least a second optical line terminal to the remote network node via a second optical channel; receiving a plurality of data packets communicated downstream by the at least first optical line terminal at the network node; and communicating the plurality of data packets upstream to the at least second optical line terminal. [09] The dedicated communication channel proposed herein can significantly decrease the communication latency between the two OLTs, thus noticeably reducing protection times. The channel can also be used to exchange information between other equipment of the same two network nodes, carry data traffic, and be used as a protection link for core links, particularly since it provides a different Shared-Risk-Link-Group with respect to core links.

[010] In an embodiment of the method according to the invention, each optical line terminal may be located at an access network core, and the network node may be located either between a plurality of access network cores and a plurality of end-user locations, or at an end-user location.

[01 1 ] In an embodiment of the method according to the invention, the network node may be a first optical network unit. [012] In an alternative embodiment of the method according to the invention, the network node may be a third optical line terminal. A variant of this embodiment of the method may comprise the further step of assigning two wavelengths, respectively for downstream and upstream communications between the first, second and third optical line terminals.

[013] A further variant may comprise the further steps of locating a waveband reflector at the network node and filtering multiple WDM channels within the bandwidth of the waveband reflector at each of the first and second optical line terminals.

[014] In an embodiment there is provided a method of placing at least one wavelength selective tap positioned after the optical amplifiers configured to provide direct wavelength "light paths" for communications channels between the two OLTs.

[015] In an embodiment of the method according to the invention, each of the first and second optical line terminals and the network node may comprise a continuous wave transceiver. A variant of this embodiment of the method may comprise the further step of assigning four wavelengths, one respectively for each of the downstream and upstream communications between the first optical line terminal and the network node and between the second optical line terminal and the network node.

[016] It will be easily understood by the skilled reader that the above principles can be scaled up across a network without difficulty, thus further optical network units and/or optical line terminals and/or continuous wave transceivers may be used, and the method would comprise the further step of assigning further wavelengths, in dependence of the number of additional ONUs, OLTs and/or CWTs for implementing additional communication channels between the first and second optical line terminals. [017] According to another aspect of the present invention, there is also provided a passive optical access network, comprising at least a first optical line terminal; at least a second optical line terminal, remote from the at least first optical line terminal; and a network node remote from the first and second optical line terminals and connected thereto via respective optical channels; wherein the network node is configured to receive a plurality of data packets from the at least first optical line terminal and to communicate same to the at least second optical line terminal. [018] In an embodiment of the network according to the invention, each optical line terminal may be located at an access network core, and the network node may be located either between a plurality of access network cores and a plurality of end-user locations, or at an end-user location.

[019] In an embodiment of the network according to the invention, the network node may be a first optical network unit.

[020] In an alternative embodiment of the network according to the invention, the network node may be a third optical line terminal. In a variant of this embodiment of the network, two wavelengths may be respectively assigned for downstream and upstream communications between the first, second and third optical line terminals. [021 ] In a further variant, the network node may further comprise a waveband reflector, and each of the first and second optical line terminals is preferably configured to filter multiple WDM channels within the bandwidth of the waveband reflector. [022] In an embodiment of the network according to the invention, each of the first and second optical line terminals and the network node may comprise a continuous wave transceiver. In a variant of this embodiment of the network, four wavelengths may be assigned, one respectively for each of the downstream and upstream communications between the first optical line terminal and the network node and between the second optical line terminal and the network node.

[023] In an embodiment the wavelength reflector after the first splitter can be replaced by at least one wavelength selective tap positioned after the optical amplifiers to provide direct wavelength "light paths" for communications channels between the two OLTs. [024] According to yet another aspect of the present invention, there is also provided a set of instructions recorded on a data carrying medium which, when read from the medium and processed by an optical network terminal operably connected with a passive optical access network, configures the optical network terminal to receive a plurality of data packets from at least a first optical line terminal and to communicate same to at least a second optical line terminal.

[025] In an embodiment of the set of instructions according to the invention, each optical line terminal may be located at an access network core, and wherein the optical network terminal is located either between a plurality of access network cores and a plurality of end-user locations, or at an end-user location.

[026] In either of the above embodiments of the set of instructions, the optical network terminal may be either a first optical network unit or a third optical line terminal.

[027] For any of the above embodiments of the method, and of the system, according to the invention, and still others, the passive optical access network may be a long-reach passive optical network (LRPON).

[028] For any of the above embodiments of the method, and of the system, according to the invention, and still others, the plurality of downstream data packets may be representative of updated ranging values for one or more downstream optical network units.

[029] Other aspects of the invention are as described herein. Brief Description of the Drawings

[030] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 illustrates a passive optical access network environment, in which a first embodiment of a system according to the invention is embodied, including at least one core network node and a plurality of remote nodes optical network units connected with optical fibres;

Figure 2 shows the passive optical access network environment of Figure 1 , in which a second embodiment of a system according to the invention is embodied; Figure 3 is a logical diagram of a typical hardware architecture of a remote node configured according to the invention as shown in Figure 1 or 2;

Figure 4 is a logical diagram of a first alternative embodiment of the hardware architecture shown in Figure 3;

Figure 5 is a logical diagram of a second alternative embodiment of the hardware architecture shown in Figure 3; and

Figure 6 is a logical diagram of a third alternative embodiment of the hardware architecture shown in Figure 3.

Detailed Description of the Drawings

[031 ] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

[032] With reference to Figures 1 and 2 herein, an example embodiment of a system according to the invention is shown within a networked environment 100 comprising a fiber optic access network operated by at least a first service provider 1 10 . The provider 1 10 administers a first metro or core network node 1 10i equipped with a primary Optical Line Terminal (OLT) 120i, connected by a primary optical network fibre 130i to a first remote node 140 configured with a first Optical Network Unit (ONU) 146.

[033] The network 100 is a Passive Optical Network (PON) 100 having a point- to-multipoint architecture, wherein the primary optical network fibre 130i is split by a splitter 145 of the first remote node 140i into a plurality of optical network sub- links 141 -1 . Thus, upon reaching a respective second remote node 140₂ downstream in the network topology, each optical network sub-link 141 _N is further split into a plurality of further optical network sub-links 142_N by the respective splitter 145 of that second remote node 140₂. The optical access network may be further sub-divided so on and so forth, depending upon the geographical extent of the network 100 and/or the density of end user points required, until the end ONU 147_N terminating the access network nearest an end user terminal 150 at a remote location 155N is reached by the last optical network sub-link 143N connecting it to the respective, penultimate remote node 140_EN-I -

[034] The first remote node 140i is also connected to a second metro or core network node 1 10₂ likewise equipped with a primary Optical Line Terminal (OLT) 120₂, by a second primary optical network fibre 130₂ and the inventive principle described herein uses the infrastructure of the access network 100 to create a downstream link 160 and an upstream link 170 between two adjacent metro/core network nodes 1 10i, 1 10₂ which, conventionally, are connected only by the core network if and when such a connection is implemented at the time of network installation.

[035] Accordingly, with reference to Figures 1 and 3 herein, the first remote node 140 is suitably configured to receive data packets communicated in a downstream link 160 via the primary optical network fibre 130i by the at least first optical line terminal 120i and to communicate that plurality of data packets, or at least a portion thereof, in an upstream link 170 via the second primary optical network fibre 130₂ to the at least second optical line terminal 120₂. [036] In the first remote node 140, the first primary optical network fibre 130i is interfaced with the first optical circulator unit 310i of a first signal processing loop 300i comprising the first and a second optical circulator units 310-i, 310₂ and first and second optical amplifiers 320i, 320₂, wherein each optical amplifier 320, is operably mounted for data communication between the two circulator units 310-i, 310₂, and a data channel connects the second optical circulator unit 310₂ of the loop to the splitter 145. [037] In the first remote node 140 still, a second data channel connects the splitter 145 to a third optical circulator unit 310₃ of a second signal processing loop 300₂ comprising the third and a fourth optical circulator unit 310₃, 310₄ and third and fourth optical amplifiers 320₃, 320₄, wherein each optical amplifier 320 is again operably mounted for data communication between the two circulator units 310₃, 310₄. Namely, the first and second signal processing loops 300i, 300₂ are substantially identical to one another and the second primary optical network link 130₂ is interfaced with the fourth optical circulator unit 310₄ of the second signal processing loop 300₂. Further fibres 131 N may be connected to the splitter 145, for ulterior use.

[038] Data packets communicated in the downstream link 160 are passed by the first signal processing loop 300i to the splitter 145 then via a relevant communication link 330 to the first Optical Network Unit (ONU) 140 of the first remote node 140, which controls all four optical amplifier 320i_-4 of both signal processing loops 300i, 300₂ through at least one control channel or link 340. This architecture provides for the use of a low-capacity channel for signalling and control messages which can be inserted into the PON system. For example, where the OLT 120i in MC node 1 10i wants to send information to the OLT 120₂ in MC node 1 10₂ for protection purposes, such as updates on ranging values for the user ONUs 147_N, the OLT 120₂ should try to get all information which the

OLT 120i has. In the upstream direction, the OLT 120₂ can listen to traffic from all ONUs 147_N, whereby it can obtain exact information. However, the OLT 120₂ cannot listen to messages sent from OLT 120-1. With the invention, the ONU 146 -l oin the first remote node 140 can forward to the OLT 120₂ those messages which the OLT 120i considers important for OLT 120i. This system uses the same channel as the rest of the PON 100, and uses a negligible amount of upstream bandwidth for relaying messages from OLT 120i to OLT 120₂.

[039] In accordance with the inventive principle disclosed herein, it will be readily understood by the skilled person that any network node downstream of the core node 1 10i may be suitably configured for data packet mirroring to the second metro or core network node 1 10₂ and, with reference now to Figures 2 and 3, even a terminating remote node 147_N terminating the access network nearest an end user terminal 150 at a remote location 155_N may be suitably configured. The downstream link 160 from the core node 1 10i is constituted by the downstream network path 160, 161 , 162, 163 (respectively, 141 _N, 142 _N, 143_N) across the respective intermediary network nodes 140N to the terminating remote node 147_N, and the upstream link 170 to the backup core node 1 10₂ is constituted by a reverse upstream network path 173, 172, 171 (respectively, 143N, 142 _N, 1 1 _N), 170 back across the same respective intermediary network nodes 140_N.

[040] Where the PON architecture allows, using an ONU 146 at the remote node 140 should be preferred, for both security and resiliency purposes. However, should more bandwidth be required, for example to implement an additional high-speed data channel between the two core nodes 1 10i, 1 10₂, a dedicated wavelength may be used for this purpose, using either an additional ONU, OLT (Figure 4) or transceivers (Figure 5), or with the addition of an optical reflector (Figure 6), as described with reference to the following alternative embodiments.

[041 ] With reference to Figure 4, in this alternative embodiment, an additional channel is used to create a bidirectional link between the metro/core nodes 1 10i, 1 10₂ configured with respective ONUs 420i, 420₂, wherein an OLT 440i is located at the remote node 140, such that only 2 wavelengths are used. [042] A first wavelength is assigned to downstream data packets received by the OLT 440i, via the splitter 145, respectively from the first ONU 420i of the first metro or core network node 1 10 and from the second ONU 420₂ of the second metro or core network node 1 10₂.

[043] A second wavelength is assigned to upstream data packets transmitted by the OLT 440_{1 ;} via the splitter 145, respectively to the first ONU 420₁ of the first metro or core network node 1 10i and to the second ONU 420₂ of the second metro or core network node 1 10₂.

[044] With reference to Figure 5 next, in this alternative embodiment, an additional channel is again used to create a bidirectional link between the metro/core nodes 1 10i, 1 10₂ configured with respective continuous wave transceivers (CWTs) 520i, 520₂, wherein two further continuous wave transceivers (CWTs) 540i, 540₂, bridged with one another (541 ) are located at the remote node 140, such that 4 wavelengths are used.

[045] A first wavelength is assigned to downstream data packets received by the first remote node CWT 540i, via the splitter 145, from the first CWT 520i of the first metro or core network node 1 10 . A second wavelength is assigned to upstream data packets transmitted by the first remote node CWT 540i, via the splitter 145, to the second CWT 520₂ of the second metro or core network node 1 10₂. [046] Reciprocally, a third wavelength is assigned to downstream data packets received by the second remote node CWT 540₂, via the splitter 145, from the second CWT 520₂ of the second metro or core network node 1 10₂. A fourth wavelength is assigned to upstream data packets transmitted by the first remote node CWT 540₂, via the splitter 145, to the first CWT 520i of the first metro or core network node 1 10 . [047] This embodiment requires two more wavelengths relative to the embodiment of Figure 4, however and advantageously it allows a bidirectional capacity equal to the full rate of the transceivers 520_N. [048] With reference to Figure 6 next, in this alternative embodiment, an additional channel is again used to create a bidirectional link between the metro/core nodes 1 10i , 1 10₂ configured with respective continuous wave transceivers (CWTs) 520i , 520₂ as in the previous embodiment shown in Figure 5. In this embodiment, however, a waveband reflector 601 is located on at least one sub-link 141 _N downstream of the splitter 145 and is used to reflect a number of predetermined wavelengths back towards the CWTs 520i , 520₂ at the metro/core nodes 1 1 0i , 1 10₂. It will be appreciated that other embodiments of wavelength reflection can also be provided depending on the application required. While a single fibre is shown working from the OLTs to the first network splitter mode, it can also in practice be two fibres working and the optical isolators shown would not be present.

[049] As with the embodiment of Figure 4, a first wavelength is assigned to downstream data packets communicated by the first CWT 520i of the first metro or core network node 1 1 0 which transit the splitter 145 and are reflected by the waveband reflector 601 back towards the second CWT 520₂ of the second metro or core network node 1 1 0₂ ; and a second wavelength is assigned to downstream data packets communicated by the second CWT 520₂ of the second metro or core network node 1 1 0₂ which transit the splitter 145 and are reflected by the waveband reflector 601 back towards the first CWT 520i of the first metro or core network node 1 1 0 .

[050] Such wavelengths will reach both the other metro or core node 1 10_N+i as well as being reflected back to the transceiver 520N, thus it is important to assure relevant filtering at each CWT 520_N. Filtering may for instance be provided by locating an additional optical circulator unit 61 ON and an optical tunable filter unit 620_N downstream of the CWT 520_N and upstream from the remote node 140. Alternatively, tunable CWTs may be used instead, for still more flexibility. Moreover, multiple WDM channels may be used for communications as far as they remain within the bandwidth of the waveband reflector 601 . [051 ] This embodiment combines the respective advantages of the embodiments of Figures 4 and 5, in that only two wavelengths are required and it advantageously allows a bidirectional capacity equal to the full rate of the transceivers 520N.

[052] The network-side termination of the PON 1 00 at the OLT ^ 20^ effectively communicates information to a second OLT 120₂ which remains in standby for protection, using messages that are relayed by an ONU 146 located in a remote node 140. It will be readily understood by the skilled reader that the message- relaying function can also be achieved by end-user equipment, whereby the invention can be practiced in optical networks which do not use a dedicated ONU 146 at the remote node 140. Therefore, according to the principles herein, existing infrastructure at the access side is re-used for creating an additional and dedicated communication link 1 60, 1 70 between two OLTs 120i , 120₂ and two adjacent nodes 1 1 0i , 1 1 0₂. In particular, because of the different routes that access links may have with respect to core links, each potentially representative of a different Share Risk Link Group (SRLG), the invention can be used to protect portions of the core network 100, achieving considerable savings by removing the need to install additional fibre. [053] The invention thus solves both the problems of reducing overall implementation difficulty, materials and costs in optical-based networks, as installed access fibre is re-used to create additional links, which would otherwise be available only in the core; and reducing the protection time for PON systems 100. The direct communication channel 1 60, 170 which it creates between OLTs 120-1 , 1 20₂ does not require data to be passed through the core network, where it could be delayed or disrupted because of the presence of other data traffic. Having the ability to offer short protection times is particularly important in a PON 100, as it allows mixing of residential and business customers into the same network, thus allowing operators to offer a better service at a lower cost.

[054] The embodiments in the invention described with reference to the drawings generally comprise a computer apparatus and/or processes performed in a computer apparatus. However, the invention also extends to computer programs, particularly computer programs stored on or in a carrier adapted to bring the invention into practice. The program may be in the form of source code, object code, or a code intermediate source and object code, such as in partially compiled form or in any other form suitable for use in the implementation of the method according to the invention. The carrier may comprise a storage medium such as ROM, e.g. CD ROM, or magnetic recording medium, e.g. a floppy disk or hard disk. The carrier may be an electrical or optical signal which may be transmitted via an electrical or an optical cable or by radio or other means.

[055] In the specification the terms "comprise, comprises, comprised and comprising" or any variation thereof and the terms include, includes, included and including" or any variation thereof are considered to be totally interchangeable and they should all be afforded the widest possible interpretation and vice versa.

[056] The invention is not limited to the embodiments hereinbefore described but may be varied in both construction and detail.

Claims

1 . A method of configuring a passive optical access network, comprising the steps of

connecting at least a first optical line terminal to a remote network node via a first optical channel ;

connecting at least a second optical line terminal to the remote network node via a second optical channel ;

receiving a plurality of data packets communicated downstream by the at least first optical line terminal at the network node ; and

communicating the plurality of data packets upstream to the at least second optical line terminal.

2. The method according to claim 1 , wherein each optical line terminal is located at an access network core, and wherein the network node is located either between a plurality of access network cores and a plurality of end-user locations, or at an end-user location.

3. The method according to claim 1 or 2, wherein the network node comprises a first optical network unit.

4. The method according to claim 1 or 2, wherein the network node comprises a third optical line terminal.

5. The method according to claim 4, comprising the further step of assigning two wavelengths, respectively for downstream and upstream communications between the first, second and third optical line terminals.

6. The method according to any preceding claim, comprising the further steps of locating a waveband reflector at the network node and filtering multiple WDM channels within the bandwidth of the waveband reflector at each of the first and second optical line terminals.

7. The method according to claim 1 or 2, wherein each of the first and second optical line terminals and the network node comprises at least one continuous wave transceiver.

8. The method according to claim 7, comprising the further step of assigning four wavelengths, one respectively for each of the downstream and upstream communications between the first optical line terminal and the network node and between the second optical line terminal and the network node.

9. The method according to any of claims 1 to 8, comprising further optical network units and/or optical line terminals and/or continuous wave transceivers, wherein the method comprises the further step of assigning further wavelengths for implementing additional communication channels between the first and second optical line terminals.

10. The method according to any of claims 1 to 9, wherein the passive optical access network is a long-reach passive optical network.

1 1 . A passive optical access network, comprising:

at least a first optical line terminal ;

at least a second optical line terminal, remote from the at least first optical line terminal; and

a network node remote from the first and second optical line terminals and connected thereto via respective optical channels;

wherein the network node is configured to receive a plurality of data packets from the at least first optical line terminal and to communicate same to the at least second optical line terminal.

12. The network according to claim 1 1 , wherein each optical line terminal is located at an access network core, and wherein the network node is located either between a plurality of access network cores and a plurality of end-user locations, or at an end-user location.

13. The network according to claim 1 1 or 12, wherein the network node is a first optical network unit.

14. The network according to claim 1 1 or 12, wherein the network node is a third optical line terminal.

15. The network according to claim 14, wherein two wavelengths are respectively assigned for downstream and upstream communications between the first, second and third optical line terminals.

16. The network according to any of claims 1 1 to 15, wherein the network node further comprises a waveband reflector, and wherein each of the first and second optical line terminals is configured to filter multiple WDM channels within the bandwidth of the waveband reflector.

17. The network according to claim 1 1 or 12, wherein each of the first and second optical line terminals and the network node comprises a continuous wave transceiver.

18. The network according to claim 17, wherein four wavelengths are assigned, one respectively for each of the downstream and upstream communications between the first optical line terminal and the network node and between the second optical line terminal and the network node.

19. The network according to any of claims 1 1 to 18, comprising further optical network units and/or optical line terminals and/or continuous wave transceivers, wherein further wavelengths are correspondingly assigned for implementing additional communication channels between the first and second optical line terminals.

20. The network according to any of claims 1 1 to 19, being a long-reach optical access network.

21 . The network according to any of claims 1 1 to 20, wherein the plurality of downstream data packets is representative of updated ranging values for one or more downstream optical network units.

22. A set of instructions recorded on a data carrying medium which, when read from the medium and processed by an optical network terminal operably connected with a passive optical access network, configures the optical network terminal to receive a plurality of data packets from at least a first optical line terminal and to communicate same to at least a second optical line terminal.

23. The set of instructions according to claim 22, wherein each optical line terminal is located at an access network core, and wherein the optical network terminal is located either between a plurality of access network cores and a plurality of end-user locations, or at an end-user location.

24. The set of instructions according to claim 22 or 23, wherein the optical network terminal is either a first optical network unit or a third optical line terminal.