CA2192098C - Access network - Google Patents
Access network Download PDFInfo
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- CA2192098C CA2192098C CA002192098A CA2192098A CA2192098C CA 2192098 C CA2192098 C CA 2192098C CA 002192098 A CA002192098 A CA 002192098A CA 2192098 A CA2192098 A CA 2192098A CA 2192098 C CA2192098 C CA 2192098C
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q11/0067—Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0005—Switch and router aspects
- H04Q2011/0007—Construction
- H04Q2011/0015—Construction using splitting combining
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/0079—Operation or maintenance aspects
- H04Q2011/0081—Fault tolerance; Redundancy; Recovery; Reconfigurability
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/009—Topology aspects
- H04Q2011/0092—Ring
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/0001—Selecting arrangements for multiplex systems using optical switching
- H04Q11/0062—Network aspects
- H04Q2011/009—Topology aspects
- H04Q2011/0096—Tree
Abstract
A telecommunications access network comprises a plurality of customer terminals (25, 30) and a plurality of network nodes (23, 28). Each network node (23, 28) is connected to a plurality of the customer terminals (25, 30) by respective local access lines (24, 29), whereby each customer terminal is connectible to a switch (11, 12) of a telecommunications core network via one of the network nodes. At least one of the customer terminals (25', 30') is connected to two of the network nodes (23, 28) by respective local access lines (24, 24' or 29, 29').
Description
'JO 95!34182 PCT/GB95/01298 ACCESS NETWORK
This invention relates to a telecommunications access network, and in particular to an optical fibre telecommunications access network.
In the United Kingdom, the telecommunications network includes a trunk network which is substantially constituted by optical fibre, and a local access network which is substantially completely constituted by copper pairs.
Flexibility in the copper access network is provided at two points en route to the customer;
firstly, at street-side cabinets serving up to 600 lines; and secondly, at distribution points (DPs) serving around 10-15 lines. Eventually, it is expected that the entire network, including the access network, will be constituted by fibre.
The ultimate goal is a fixed, resilient, transparent telecommunications infrastructure for the optical access network, with capacity for all foreseeable service requirements. One way of achieving this would be to create a fully-managed fibre network ir? the form of a thin, widespread overlay for the whole access topography, as this would exploit the existing valuable access network infrastructure. Such a network could be equipped as needs arise, and thereby could result in capital expenditure savings, since the major part of the investment will be the provision of terminal equipment on a 'just in time' basis. It should also enable the rapid provision of extra lines to new or existing customers, and flexible provision or reconfiguration of telephony services.
In order to be future proof, the network should be single mode optical fibre, with no bandwidth limiting active electronics within the infrastructure.
Passive optical networks (PONs) offer total transparency and freedom for upgrade.
The most common optical network is the simplex single star, with point-to-point fibre for each transmit and receive path, from the exchange head end (HE) to the customer network terminating equipment (NTE). This network design involves high fibre count cables, and unique electro-optic provision at HE and NTE
for each customer. The resulting inherent cost can only be justified for large business users, who generally also require the security of diverse routing, which increases the cost still further.
The advent of optical splitters (power dividers) allows the power transmitted from a single transmitter to be distributed amongst several customers, 2 219 2 ~ 9 g PCT/GB95/01298 thereby reducing and sharing the capital investment. In 1987, BT demonstrated this technology in a system for telephony on a passive optical network (TPON), with a 128-way split and using time division multiplex (TDM) running at 20Mb/s.
This combination enabled basic rate integrated service digital network (ISDN) to be provided to all customers. In practice, the competitive cost constraint of the existing copper network precludes domestic customers from having just telephony over fibre, due to the high capital cost of equipment. This may change in the future. In the meantime, telephony for small business users (for example those having more than 5 lines) can probably break this barrier.
The wider range of services and higher capacity required by business customers makes a 32-way split more attractive for a 20Mb/s system, and this has been demonstrated by BT's local loop optical field trial fLLOFT) at Bishop's Stortford.
In summary, the use of splitter-based PON architecture will reduce the cost of fibre deployment in the access network. When compared with point-to point fibre, savings will result from:
Ii) reducing the number of fibres at the exchange and in the network;
(ii) reducing the amount of terminal equipment at the exchange;
f iii) sharing the cost of equipment amongst a number of customers;
(iv) providing a thin, widespread, low cost, fibre infrastructure; and (v) providing a high degree of flexibility, and allowing 'just in-time' equipment and service provision.
Additionally, PON architecture can be tailored to suit the existing infrastructure resources (duct and other civil works).
Total network transparency will retain the option for future services to be provided on different wavelengths to the telecommunications, which for TPON is in the 1300nm window. By transmitting at other wavelengths, other services, such as broadband access for cable television and high definition television, or business services, such as high bit rate data, video telephony or video conferencing, can be provided. The huge bandwidth potential of fibre promises virtually unlimited capacity for the transparent network. Eventually, it may be possible to transmit hundreds of wavelengths simultaneously, as the development of technology in optical components, such as narrow band lasers, wavelength division multiplexers (WDMs), optical filters, fibre amplifiers and tuneable devices, moves forward.
For this potential to remain available, and for the access network to be used to provide many and varied services, then it must be designed and engineered to provide very high levels of security and resilience. Even for simple POTS
(plain old telephony servicel, advance warning and live maintenance are essential to limit disruption.
A particularly important aspect of resilience is the reliability of the network, and this is particularly the case for business customers. Thus, even if a business customer has several lines, these will tend to come from the same DP, so that a failure between that DP and the up-stream cabinet, or a failure between that cabinet and the exchange, or even a failure at the exchange itself will result in loss of service to that customer. The problem of resilience is discussed in "Commutation et Transmission, vol. 14, no. 4, 1992, Paris, FR, pages 27 - 34, J. ABIVEN et al.
MOLENE: Systeme de distribution d'acces a 2 Mbit/s sur reseau optique passif"
and "Commutation et Transmission, vol. 15, no. 1, 1993, Paris, FR, pages 5 - 10, D.
Bertinet et al.: Reseaux optiques flexibles," wherein resilience is achieved with the provision of a dependent, duplicated backup network.
The present invention provides a telecommunications local access network comprising at least two independent subnetworks wherein each of said independent subnetworks serves a respective group of user terminations in the same local area, and wherein each subnetwork comprises transmission links connecting the respective group of user terminations to a respective switch of a telecommunications core network, wherein a plurality of user terminations are each served by at least a first and a second of said independent subnetworks so that telecommunications services) are routinely available thereto over both of said first and second subnetworks with services) continuing to be provided from one of said first and second subnetworks in the event that the other of said first and second subnetworks fails.
In a preferred embodiment, each independent subnetwork further comprises network nodes, wherein each respective group of user terminations are connected to each respective switch with transmissions links via respective network nodes.
This invention relates to a telecommunications access network, and in particular to an optical fibre telecommunications access network.
In the United Kingdom, the telecommunications network includes a trunk network which is substantially constituted by optical fibre, and a local access network which is substantially completely constituted by copper pairs.
Flexibility in the copper access network is provided at two points en route to the customer;
firstly, at street-side cabinets serving up to 600 lines; and secondly, at distribution points (DPs) serving around 10-15 lines. Eventually, it is expected that the entire network, including the access network, will be constituted by fibre.
The ultimate goal is a fixed, resilient, transparent telecommunications infrastructure for the optical access network, with capacity for all foreseeable service requirements. One way of achieving this would be to create a fully-managed fibre network ir? the form of a thin, widespread overlay for the whole access topography, as this would exploit the existing valuable access network infrastructure. Such a network could be equipped as needs arise, and thereby could result in capital expenditure savings, since the major part of the investment will be the provision of terminal equipment on a 'just in time' basis. It should also enable the rapid provision of extra lines to new or existing customers, and flexible provision or reconfiguration of telephony services.
In order to be future proof, the network should be single mode optical fibre, with no bandwidth limiting active electronics within the infrastructure.
Passive optical networks (PONs) offer total transparency and freedom for upgrade.
The most common optical network is the simplex single star, with point-to-point fibre for each transmit and receive path, from the exchange head end (HE) to the customer network terminating equipment (NTE). This network design involves high fibre count cables, and unique electro-optic provision at HE and NTE
for each customer. The resulting inherent cost can only be justified for large business users, who generally also require the security of diverse routing, which increases the cost still further.
The advent of optical splitters (power dividers) allows the power transmitted from a single transmitter to be distributed amongst several customers, 2 219 2 ~ 9 g PCT/GB95/01298 thereby reducing and sharing the capital investment. In 1987, BT demonstrated this technology in a system for telephony on a passive optical network (TPON), with a 128-way split and using time division multiplex (TDM) running at 20Mb/s.
This combination enabled basic rate integrated service digital network (ISDN) to be provided to all customers. In practice, the competitive cost constraint of the existing copper network precludes domestic customers from having just telephony over fibre, due to the high capital cost of equipment. This may change in the future. In the meantime, telephony for small business users (for example those having more than 5 lines) can probably break this barrier.
The wider range of services and higher capacity required by business customers makes a 32-way split more attractive for a 20Mb/s system, and this has been demonstrated by BT's local loop optical field trial fLLOFT) at Bishop's Stortford.
In summary, the use of splitter-based PON architecture will reduce the cost of fibre deployment in the access network. When compared with point-to point fibre, savings will result from:
Ii) reducing the number of fibres at the exchange and in the network;
(ii) reducing the amount of terminal equipment at the exchange;
f iii) sharing the cost of equipment amongst a number of customers;
(iv) providing a thin, widespread, low cost, fibre infrastructure; and (v) providing a high degree of flexibility, and allowing 'just in-time' equipment and service provision.
Additionally, PON architecture can be tailored to suit the existing infrastructure resources (duct and other civil works).
Total network transparency will retain the option for future services to be provided on different wavelengths to the telecommunications, which for TPON is in the 1300nm window. By transmitting at other wavelengths, other services, such as broadband access for cable television and high definition television, or business services, such as high bit rate data, video telephony or video conferencing, can be provided. The huge bandwidth potential of fibre promises virtually unlimited capacity for the transparent network. Eventually, it may be possible to transmit hundreds of wavelengths simultaneously, as the development of technology in optical components, such as narrow band lasers, wavelength division multiplexers (WDMs), optical filters, fibre amplifiers and tuneable devices, moves forward.
For this potential to remain available, and for the access network to be used to provide many and varied services, then it must be designed and engineered to provide very high levels of security and resilience. Even for simple POTS
(plain old telephony servicel, advance warning and live maintenance are essential to limit disruption.
A particularly important aspect of resilience is the reliability of the network, and this is particularly the case for business customers. Thus, even if a business customer has several lines, these will tend to come from the same DP, so that a failure between that DP and the up-stream cabinet, or a failure between that cabinet and the exchange, or even a failure at the exchange itself will result in loss of service to that customer. The problem of resilience is discussed in "Commutation et Transmission, vol. 14, no. 4, 1992, Paris, FR, pages 27 - 34, J. ABIVEN et al.
MOLENE: Systeme de distribution d'acces a 2 Mbit/s sur reseau optique passif"
and "Commutation et Transmission, vol. 15, no. 1, 1993, Paris, FR, pages 5 - 10, D.
Bertinet et al.: Reseaux optiques flexibles," wherein resilience is achieved with the provision of a dependent, duplicated backup network.
The present invention provides a telecommunications local access network comprising at least two independent subnetworks wherein each of said independent subnetworks serves a respective group of user terminations in the same local area, and wherein each subnetwork comprises transmission links connecting the respective group of user terminations to a respective switch of a telecommunications core network, wherein a plurality of user terminations are each served by at least a first and a second of said independent subnetworks so that telecommunications services) are routinely available thereto over both of said first and second subnetworks with services) continuing to be provided from one of said first and second subnetworks in the event that the other of said first and second subnetworks fails.
In a preferred embodiment, each independent subnetwork further comprises network nodes, wherein each respective group of user terminations are connected to each respective switch with transmissions links via respective network nodes.
Thus, if one of the transmission links (or one of the associated network nodes) of said at least one user termination fails, that user can still receive service via its other transmission link, thereby providing that user with resilience.
In a preferred embodiment, the network nodes are configured at first level nodes associated with a switch and second level node, each first level network node being connected to a plurality of the second level network nodes by respective transmission links. Advantageously, said at least one user termination may be connected to two second level network nodes. Alternatively, said at least one user termination may be connected to two first level network nodes. Thus, customers can be provided with resilience at either the DP (second level of network nodes) level, or at the cabinet (first level of network nodes) level. In either case, resilience is provided at all network node levels downstream of the core network switch.
Preferably, each of said independent subnetworks is connected to a different switch of the core network. In this way, further resilience is provided in that users provided with resilience can still receive service even if one of the switches fails.
Connection to the first level of network nodes may be provided by a ring of transmission links. Conveniently, each of said rings may be connected to its respective switch via a respective concentrator and a further ring.
Advantageously, the transmission links are constituted by optical fibres. In this case, each of said independent subnetworks may constitute a PON.
The invention will now be described in greater detail, byway of example, with reference to the accompanying drawings, in which:-Figure 1 is a schematic representation of a telecommunications network which illustrates the principle of the invention;
Figure 2 is a schematic representation of a first form of telecommunications network embodying the invention; and Figure 3 is a schematic representation of a second form of telecommunications network embodying the invention.
Referring to the drawings, Fig. 1 is a schematic representation of a telecommunications access network having first and second fibre rings 1 and 2, each of which is centred on a local exchange (not shown). The ring 1 is provided with a plurality of nodes 3, each of which is connected to a plurality of customer premises 4 by respective optical fibres 5. Similarly, the ring 2 is provided with a plurality of nodes 6, each of which is connected to a plurality of customer premises 7 by respective optical fibres 8. Each of the nodes 3 and 6 is constituted by a passive optical splitter, so that these nodes can be considered as DPs.
In order to provide resilience, some of the customer premises of the ring 1 (identified by the reference numerals 4') are connected to nearby nodes 6 of the 5 ring 2 by respective optical fibres 5'. Similarly, some of the customer premises of the ring 2 (identified by the reference numerals 7') are connected to nearby nodes 3 of the ring 1 by respective optical fibres 8'. The optical fibres 5 and 8 are termed "main" fibres, and the optical fibres 5' and 8' are termed "standby"
fibres.
The customer premises 4' and 7' are, therefore, each connected to both rings 1 and 2, thereby ensuring that those premises receive service if their main fibres 5 and 8 fail, or if either of the rings 1 and 2 fails, or if either of the associated nodes 3 and 6 fails. If further resilience is required, the two rings 1 and 2 would be centred on different local exchanges, thereby protecting customers opting for resilience against exchange failure as well as against fibre failure.
Figure 2 shows a practical realisation of the invention which embodies the principle of interleaved PONs. The access network of Figure 2 includes two adjacent digital local exchanges (DLEs) 11 and 12 associated respectively with PONS 13 and 14. The PON 13 is connected to the DLE 11 via a fibre ring 15, a concentrator 16, and a synchronous digital hierarchy (SDH) fibre ring 17.
Similarly, the PON 14 is connected to the DLE 12 via a fibre ring 18, a concentrator 19, and an SDH ring 20.
The PON 13 has three levels of split, including a first splitter 21 associated with the ring 15, and having a 2x4-way split. The second level of split is constituted by four splitters 22, each having a 4-way split. The third level of split is constituted by sixteen splitters 23, each having a 16-way split. The splitters 23 can be considered as DPs. Respective optical fibres 24 lead from each of the splitters 23 to associated customer premises 25. For reasons of clarity, not all the splitters 22, 23 and 24 and the associated fibres and customer premises are shown in Figure 2.
Similarly, the PON 14 has three levels of split, including a first splitter 26 associated with the ring 18 and having a 2x4-way split. The second level of split is constituted by four splitters 27, each having a 16-way split. The third level of split is constituted by sixteen splitters 28, each having a 16-way split. The splitters 28 can be considered as DPs. Respective optical fibres 29 lead from each of the splitters 28 to associated customer premises 30. For reasons of clarity, not all the splitters 26, 27 and 28 and the associated fibres and customer premises are shown in Figure 2.
In order to provide resilience, some of the customer premises of the ring (identified by the reference numerals 25') are connected to nearby splitters of the ring 18 by respective optical fibres 24'. Similarly, some of the customer premises of the ring 18 (identified by the reference numerals 30') are connected to nearby splitters of the ring 15 by respective optical fibres 29'. The customer 10 premises 25' and 30' are, therefore, each connected to both the rings 15 and 18, thereby ensuring that those premises receive service if their main fibres 24 and 29 fail, or if any of the rings 15, 17, 18 and 20 fails, or if any associated interconnecting node (spiitter) 21, 22, 23, 26, 27 or 28 fails. As the rings 15 and 18 are centred on different DLEs 11 and 12, the customers opting for resilience 15 are also protected against exchange failure as well as against fibre or node failure.
The embodiment of Figure 2 also shows a further form of resilience, in that a customer premises 30" (which may be, for example, the premises of a large business customer) is connected directly to adjacent splitters 22 and 27 of the two PONs 13 and 14 by respective fibres 31 and 32.
Figure 3 shows a second form of access network embodying the principle of interleaved PONs. The network of Figure 3 is very similar to that of Figure 2, and so like reference numerals are used for similar parts, and only the modifications will be described in detail. The main modification shown in Figure 3 is that each of the rings 15 and 18 is associated with both the concentrators and 19, so that each of the PONs 13 and 14 is connected to each of the DLEs 1 and 12. This gives additional resilience to customers not connected to splitters 23 and 28 of the two rings 15 and 18. This network has the further advantage of providing additional resilience to customers connected to splitters 23 and 28 of the two rings 15 and 18 in that protection is provided against two failures in the network, as alternative routes round faults are available.
The interleaved PONs of the networks of Figures 2 and 3 ensure that the DPs (that is to say the splitters 23 and 28) are fed alternately to the DLEs 1 1 and 12. Customers who require a highly resilient service could pick up connections 2192098 , ,, ; . , JVO 95134182 PCT/GB95l01298 from both the DLEs 11 and 12, thereby providing such customers with separate routes to the two DLEs. Consequently, there is no duplication of any hardware, apart from the final drop from the DPs to the customers. In the event of any DLE, concentrator or link failure, another connection route is always available.
It should be noted that, in each of the embodiments described above, only those customers who require resilience would be supplied with both main and standby fibres. Moreover, in principle, there is no distinction between main and standby fibres, so that customers opting for resilience could choose to operate using a main and standby approach, or could split their traffic between the two connections.
It should be apparent that modifications could be made to the networks described above. In particular, the principle of the invention could be incorporated into local access network arrangements utilising copper pairs as the local access lines. In this case, customers requiring resilience would be connected to the DPs of two local access networks centred on different local exchanges by separate copper pairs. It would also be possible to use the principle of the invention in local access networks having radio transmitters providing the final drop to customers.
In this case, customers requiring resilience would be provided with two narrow angle transmitters, each of which would be directed towards respective nearby DPs of two local access networks centred on different local exchanges.
In a preferred embodiment, the network nodes are configured at first level nodes associated with a switch and second level node, each first level network node being connected to a plurality of the second level network nodes by respective transmission links. Advantageously, said at least one user termination may be connected to two second level network nodes. Alternatively, said at least one user termination may be connected to two first level network nodes. Thus, customers can be provided with resilience at either the DP (second level of network nodes) level, or at the cabinet (first level of network nodes) level. In either case, resilience is provided at all network node levels downstream of the core network switch.
Preferably, each of said independent subnetworks is connected to a different switch of the core network. In this way, further resilience is provided in that users provided with resilience can still receive service even if one of the switches fails.
Connection to the first level of network nodes may be provided by a ring of transmission links. Conveniently, each of said rings may be connected to its respective switch via a respective concentrator and a further ring.
Advantageously, the transmission links are constituted by optical fibres. In this case, each of said independent subnetworks may constitute a PON.
The invention will now be described in greater detail, byway of example, with reference to the accompanying drawings, in which:-Figure 1 is a schematic representation of a telecommunications network which illustrates the principle of the invention;
Figure 2 is a schematic representation of a first form of telecommunications network embodying the invention; and Figure 3 is a schematic representation of a second form of telecommunications network embodying the invention.
Referring to the drawings, Fig. 1 is a schematic representation of a telecommunications access network having first and second fibre rings 1 and 2, each of which is centred on a local exchange (not shown). The ring 1 is provided with a plurality of nodes 3, each of which is connected to a plurality of customer premises 4 by respective optical fibres 5. Similarly, the ring 2 is provided with a plurality of nodes 6, each of which is connected to a plurality of customer premises 7 by respective optical fibres 8. Each of the nodes 3 and 6 is constituted by a passive optical splitter, so that these nodes can be considered as DPs.
In order to provide resilience, some of the customer premises of the ring 1 (identified by the reference numerals 4') are connected to nearby nodes 6 of the 5 ring 2 by respective optical fibres 5'. Similarly, some of the customer premises of the ring 2 (identified by the reference numerals 7') are connected to nearby nodes 3 of the ring 1 by respective optical fibres 8'. The optical fibres 5 and 8 are termed "main" fibres, and the optical fibres 5' and 8' are termed "standby"
fibres.
The customer premises 4' and 7' are, therefore, each connected to both rings 1 and 2, thereby ensuring that those premises receive service if their main fibres 5 and 8 fail, or if either of the rings 1 and 2 fails, or if either of the associated nodes 3 and 6 fails. If further resilience is required, the two rings 1 and 2 would be centred on different local exchanges, thereby protecting customers opting for resilience against exchange failure as well as against fibre failure.
Figure 2 shows a practical realisation of the invention which embodies the principle of interleaved PONs. The access network of Figure 2 includes two adjacent digital local exchanges (DLEs) 11 and 12 associated respectively with PONS 13 and 14. The PON 13 is connected to the DLE 11 via a fibre ring 15, a concentrator 16, and a synchronous digital hierarchy (SDH) fibre ring 17.
Similarly, the PON 14 is connected to the DLE 12 via a fibre ring 18, a concentrator 19, and an SDH ring 20.
The PON 13 has three levels of split, including a first splitter 21 associated with the ring 15, and having a 2x4-way split. The second level of split is constituted by four splitters 22, each having a 4-way split. The third level of split is constituted by sixteen splitters 23, each having a 16-way split. The splitters 23 can be considered as DPs. Respective optical fibres 24 lead from each of the splitters 23 to associated customer premises 25. For reasons of clarity, not all the splitters 22, 23 and 24 and the associated fibres and customer premises are shown in Figure 2.
Similarly, the PON 14 has three levels of split, including a first splitter 26 associated with the ring 18 and having a 2x4-way split. The second level of split is constituted by four splitters 27, each having a 16-way split. The third level of split is constituted by sixteen splitters 28, each having a 16-way split. The splitters 28 can be considered as DPs. Respective optical fibres 29 lead from each of the splitters 28 to associated customer premises 30. For reasons of clarity, not all the splitters 26, 27 and 28 and the associated fibres and customer premises are shown in Figure 2.
In order to provide resilience, some of the customer premises of the ring (identified by the reference numerals 25') are connected to nearby splitters of the ring 18 by respective optical fibres 24'. Similarly, some of the customer premises of the ring 18 (identified by the reference numerals 30') are connected to nearby splitters of the ring 15 by respective optical fibres 29'. The customer 10 premises 25' and 30' are, therefore, each connected to both the rings 15 and 18, thereby ensuring that those premises receive service if their main fibres 24 and 29 fail, or if any of the rings 15, 17, 18 and 20 fails, or if any associated interconnecting node (spiitter) 21, 22, 23, 26, 27 or 28 fails. As the rings 15 and 18 are centred on different DLEs 11 and 12, the customers opting for resilience 15 are also protected against exchange failure as well as against fibre or node failure.
The embodiment of Figure 2 also shows a further form of resilience, in that a customer premises 30" (which may be, for example, the premises of a large business customer) is connected directly to adjacent splitters 22 and 27 of the two PONs 13 and 14 by respective fibres 31 and 32.
Figure 3 shows a second form of access network embodying the principle of interleaved PONs. The network of Figure 3 is very similar to that of Figure 2, and so like reference numerals are used for similar parts, and only the modifications will be described in detail. The main modification shown in Figure 3 is that each of the rings 15 and 18 is associated with both the concentrators and 19, so that each of the PONs 13 and 14 is connected to each of the DLEs 1 and 12. This gives additional resilience to customers not connected to splitters 23 and 28 of the two rings 15 and 18. This network has the further advantage of providing additional resilience to customers connected to splitters 23 and 28 of the two rings 15 and 18 in that protection is provided against two failures in the network, as alternative routes round faults are available.
The interleaved PONs of the networks of Figures 2 and 3 ensure that the DPs (that is to say the splitters 23 and 28) are fed alternately to the DLEs 1 1 and 12. Customers who require a highly resilient service could pick up connections 2192098 , ,, ; . , JVO 95134182 PCT/GB95l01298 from both the DLEs 11 and 12, thereby providing such customers with separate routes to the two DLEs. Consequently, there is no duplication of any hardware, apart from the final drop from the DPs to the customers. In the event of any DLE, concentrator or link failure, another connection route is always available.
It should be noted that, in each of the embodiments described above, only those customers who require resilience would be supplied with both main and standby fibres. Moreover, in principle, there is no distinction between main and standby fibres, so that customers opting for resilience could choose to operate using a main and standby approach, or could split their traffic between the two connections.
It should be apparent that modifications could be made to the networks described above. In particular, the principle of the invention could be incorporated into local access network arrangements utilising copper pairs as the local access lines. In this case, customers requiring resilience would be connected to the DPs of two local access networks centred on different local exchanges by separate copper pairs. It would also be possible to use the principle of the invention in local access networks having radio transmitters providing the final drop to customers.
In this case, customers requiring resilience would be provided with two narrow angle transmitters, each of which would be directed towards respective nearby DPs of two local access networks centred on different local exchanges.
Claims (10)
1. A telecommunications local access network comprising at least two independent subnetworks (1, 2, 13, 14), wherein each of said independent subnetworks (1, 2, 13, 14) serves a respective group of user terminations (4, 4', 7, 7'; 25, 25', 30, 30') in the same local area, and wherein each subnetwork (1, 2, 13, 14) comprises transmission links (5, 8, 29) connecting the respective group of user terminations (4, 4', 7, 7'; 25, 25', 30, 30') to a respective switch (11, 12) of a telecommunications core network, wherein a plurality of user terminations (4', 7', 25', 30') are each served by at least a first (1, 13) and a second (2, 14) of said independent subnetworks so that telecommunications services) are routinely available thereto over both of said first (1, 13) and second (2, 14) subnetworks with service(s) continuing to be provided from one of said first (1, 13) and second (2, 14) subnetworks in the event that the other of said first (1, 13) and second (2, 14) subnetworks fails.
2. A network as claimed in claim 1, wherein each independent subnetwork further comprises network nodes (3, 6; 21, 22, 23, 26, 27, 28), wherein each respective group of user terminations are connected to each respective switch (11, 12) with transmission links (5, 8, 29) via respective network nodes (3, 6; 21, 22, 23, 26,27, 28).
3. A network as claimed in claim 2, wherein the network nodes are configured as first level nodes (21, 26) associated with a switch and second level nodes (22, 23, 27, 28), each first level network (21, 26) node being connected to a plurality of the second level network nodes (22, 23, 27, 28) by respective transmission links (5, 8, 29).
4. A network as claimed in claim 3, wherein connection to first level nodes (21, 26) is provided by a ring of transmission links (15, 18) associated with the respective switch (11, 12).
5. A network as claimed in claim 4, wherein each ring of transmission links (15, 18) is connected to its respective switch (11, 12) via a respective concentrator (16, 19) and a further ring of transmission links (17, 20).
6. A network as claimed in any of claims 3 to 5, wherein said at least one user termination (4, 7, 24, 25, 30) is connected to two second level network nodes (22, 23, 27, 28).
7. A network as claimed in any of claims 3 to 5, wherein said at least one user termination (4', 7', 24', 25', 30') is connected to two first level network nodes (21, 26).
8. A network as claimed in any one of claims 1 to 7 wherein each said subnetwork (13, 14) is connected to a different switch (11, 12) of the core network.
9. A network as claimed in any one of claims 1 to 8, wherein said transmission links (5, 8, 29) are constituted by optical fibres.
10. A network as claimed in claim 9 wherein each said subnetwork (13, 14) is a passive optical network.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP94304139.2 | 1994-06-08 | ||
| EP94304139 | 1994-06-08 | ||
| PCT/GB1995/001298 WO1995034182A1 (en) | 1994-06-08 | 1995-06-06 | Access network |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2192098A1 CA2192098A1 (en) | 1995-12-14 |
| CA2192098C true CA2192098C (en) | 2001-01-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002192098A Expired - Lifetime CA2192098C (en) | 1994-06-08 | 1995-06-06 | Access network |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5920410A (en) |
| EP (1) | EP0766903A1 (en) |
| JP (1) | JPH10501378A (en) |
| KR (1) | KR970704321A (en) |
| CN (1) | CN1150514A (en) |
| AU (1) | AU697597B2 (en) |
| CA (1) | CA2192098C (en) |
| WO (1) | WO1995034182A1 (en) |
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| US6751417B1 (en) | 1999-02-17 | 2004-06-15 | At&T Corp. | Fiber and wire communication system |
| US7190903B1 (en) | 1999-02-17 | 2007-03-13 | At&T Corp. | Fiber and wire communication system |
| US6654563B1 (en) | 1999-02-17 | 2003-11-25 | At&T Corp. | Fiber/wired communication system |
| US7283749B1 (en) * | 1999-02-17 | 2007-10-16 | At&T Corp. | Fiber and wire communication system |
| US7272321B1 (en) | 1999-05-10 | 2007-09-18 | Alloptic, Inc. | Passive optical network |
| EP1087556B1 (en) * | 1999-09-22 | 2008-07-02 | Lucent Technologies Inc. | Optical network with power splitters |
| US6771964B1 (en) | 1999-09-24 | 2004-08-03 | Nokia Networks | Handover between wireless telecommunication networks/systems |
| US7028071B1 (en) | 2000-01-28 | 2006-04-11 | Bycast Inc. | Content distribution system for generating content streams to suit different users and facilitating e-commerce transactions using broadcast content metadata |
| US6725274B1 (en) * | 2000-03-29 | 2004-04-20 | Bycast Inc. | Fail-safe system for distributing streaming media having a dynamically reconfigurable hierarchy of ring or mesh topologies |
| EP1176765A1 (en) * | 2000-07-24 | 2002-01-30 | Lucent Technologies Inc. | Method and system for providing end-to-end protection in point-to-multipoint access networks |
| EP1182903A1 (en) * | 2000-08-21 | 2002-02-27 | Lucent Technologies Inc. | Point-to-point protection in point-to-multipoint networks |
| EP1182904A1 (en) * | 2000-08-21 | 2002-02-27 | Lucent Technologies Inc. | Protection switching for duplex ATM-PON systems |
| JP2002077212A (en) * | 2000-09-01 | 2002-03-15 | Mitsubishi Electric Corp | Optical multi-branch communication system |
| JP2002152135A (en) * | 2000-09-04 | 2002-05-24 | Mitsubishi Electric Corp | Optical multi-branch communication system |
| US20030048501A1 (en) * | 2001-09-12 | 2003-03-13 | Michael Guess | Metropolitan area local access service system |
| US7228072B2 (en) * | 2001-10-16 | 2007-06-05 | Telefonaktiebolaget Lm Ericsson (Publ) | System and method for integrating a fiber optic fixed access network and a fiber optic radio access network |
| CN100452679C (en) * | 2002-12-31 | 2009-01-14 | 北京邮电大学 | Method and device for elastic protection conversion in Ethernet passive optic network system |
| US7756018B2 (en) * | 2005-11-03 | 2010-07-13 | Alcatel Lucent | System and method for implementing fast layer 2 protection in passive optical networks |
| EP1814264A1 (en) * | 2006-01-25 | 2007-08-01 | BRITISH TELECOMMUNICATIONS public limited company | Preventing loss of service resulting from damage to an end user's access connection |
| TWI400900B (en) * | 2009-01-20 | 2013-07-01 | Univ Nat Chiao Tung | Optical sensing system with self - sensing mechanism |
| US8244139B1 (en) * | 2009-02-12 | 2012-08-14 | Rockwell Collins, Inc. | System and method for providing cascaded optical line terminals (OLTs) in passive optical networks (PONs) |
| WO2010112845A1 (en) * | 2009-03-31 | 2010-10-07 | British Telecommunications | Optical fibre network |
| US10812325B1 (en) * | 2019-05-28 | 2020-10-20 | At&T Intellectual Property I, L.P. | Service bandwidth provisioning on passive optical networks |
| WO2021186714A1 (en) * | 2020-03-19 | 2021-09-23 | 日本電信電話株式会社 | Communication system and onu system |
| US20220416894A1 (en) * | 2021-06-24 | 2022-12-29 | Electronics And Telecommunications Research Institute | Rof-based distributed antenna system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS62290219A (en) * | 1986-06-10 | 1987-12-17 | Hitachi Ltd | Two-way optical transmission network |
| EP0617876B1 (en) * | 1991-12-19 | 1997-02-12 | Nortel Networks Corporation | Fibre optic telephone loop network |
| JPH07321744A (en) * | 1994-05-27 | 1995-12-08 | Nec Corp | Optical network and analog relay node |
-
1995
- 1995-06-06 JP JP8500557A patent/JPH10501378A/en not_active Ceased
- 1995-06-06 AU AU26253/95A patent/AU697597B2/en not_active Ceased
- 1995-06-06 KR KR1019960707068A patent/KR970704321A/en active IP Right Grant
- 1995-06-06 CA CA002192098A patent/CA2192098C/en not_active Expired - Lifetime
- 1995-06-06 EP EP95921050A patent/EP0766903A1/en not_active Withdrawn
- 1995-06-06 US US08/737,641 patent/US5920410A/en not_active Expired - Lifetime
- 1995-06-06 CN CN95193508A patent/CN1150514A/en active Pending
- 1995-06-06 WO PCT/GB1995/001298 patent/WO1995034182A1/en not_active Application Discontinuation
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| Publication number | Publication date |
|---|---|
| AU697597B2 (en) | 1998-10-08 |
| CN1150514A (en) | 1997-05-21 |
| KR970704321A (en) | 1997-08-09 |
| CA2192098A1 (en) | 1995-12-14 |
| WO1995034182A1 (en) | 1995-12-14 |
| EP0766903A1 (en) | 1997-04-09 |
| JPH10501378A (en) | 1998-02-03 |
| AU2625395A (en) | 1996-01-04 |
| US5920410A (en) | 1999-07-06 |
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