WO2013072776A2

WO2013072776A2 - Method and apparatus of multi-service bandwidth allocation in ethernet passive optical network

Info

Publication number: WO2013072776A2
Application number: PCT/IB2012/003052
Authority: WO
Inventors: Rui Zhou; Lei Wang; Haoyuan MA; Yonghua HAN
Original assignee: Alcatel Lucent
Priority date: 2011-06-08
Filing date: 2012-06-08
Publication date: 2013-05-23
Also published as: WO2013072776A3; CN102821029A; CN102821029B

Abstract

The present invention provides a method and apparatus of multi-service bandwidth allocation in an Ethernet Passive Optical Network (EPON) System. The System comprises the Optical Line Termination (OLT) and several Optical Network Units (ONUs) connected to the OLT, wherein, ONUs locally distinguish the types of service flows and allocate different logical link channels to each service flow based on its type, while OLT selects different bandwidth allocation methods and corresponding service scheduling for the logical link channels based on the types of service flows; ON Us perform corresponding local service scheduling based on the bandwidth allocation methods. ONUs may further identify the user group properties of the service flows, OLT and ON Us can schedule the services reasonably according to the characteristics of user groups to meet the requirements on user bandwidth or service application. As to the Multi-Dwelling Unit/Multi-Tenant Unit type of ONU, the present invention can effectively solve the limitations of application on multiple users and multiple services.

Description

METHOD AND APPARATUS OF MULTI-SERVICE BANDWIDTH

ALLOCATION IN ETHERNET PASSIVE OPTICAL NETWORK

FIELD OF THE INVENTION

[0001] The present invention relates to the field of communication technology, and more specifically, to a method and an apparatus of service bandwidth allocation in an Ethernet Passive Optical Network (EPON) system

BACKGROUND OF THE INVENTION

[0002] Passive Optical Network (PON) system is an ideal solution for the multi-service carrying, high bandwidth multimedia service access network technology. PON technology substantially includes EPON, GPON and the like, with the main difference therebetween lying in the employment of distinguishing second layer technologies. EPON, which perfectly combines the Ethernet technology with PON technology, emerges to be an appropriate broadband access technology for IP services. However, it becomes a potential technical problem how to guarantee the Quality of Service (QoS) of various broadband services transmitted on EPON.

[0003] An EPON network system can carry various broadband services simultaneously, including IP (Ethernet) service, voice service, TDM service, CATV service and the like. However, different types of services differ enormously from each other in QoS requirements. Taking TDM service as an example, it requires that the carrying network should absolutely guarantee a low- delay and error-free transmission. To meet such service requirements of TDM service, EPON system has to employ the fixed bandwidth reserving and short frame-packaging technology.

[0004] The complexity of application scenarios of EPON network results in the diverse forms of Optical Network Unit (ONU) in the network. Based on the differences in interface and number of service types, ONU can be divided into types such as Single Family Unit/Single Business Unit (SFU/SBU) and Multi-Dwelling Unit/Multi-Tenant Unit (MDU/MTU). [0005] For ONU of the SFU/SBU type, it only accesses a single user, and various types of services share one logical link channel (LLID), such that it would be impossible to distinguish traffic service levels on the EPON layer, and the differentiated service ability can merely be provided on Layer 2.

[0006] For ONU of the MDU/MTU type, it needs to access a plurality of independent users. Generally, several logical link channels LLIDs are required to provide a multi-user and multi-service carrying. MDU/MTU can provide a plurality of Ethernet interfaces (or several SDL interfaces), and provide POTS interfaces to satisfy the user's need for voice service. Some of MDU/MTUs can even provide several E1 interfaces so as to satisfy business user's need for TDM service.

[0007] Therefore, Although MDU/MTU may guarantee QoS by identifying the priority of different types of services and scheduling the priority at the Optical Line Termination (OLT) side, for the EPON system, its EPON Media Access Controller (EPON MAC) is responsible for system-specific transmission control protocol, controlling EPON burst mode data transmission. OLT receives the uplink data in a coordinating way, so as to guarantee that the data bursts from the OUNs will not conflict one another. Currently, The EPON MAC is very expensive, and at most 8 EPON MACs (corresponding to the corresponding LLIDs) can be configured for a single MDU/MTU; but for an MDU, it generally has as most as 256 physical interfaces, and it is apparently not enough to distinguish multi-user and multi-service bandwidth requirements from several physical interfaces by using only 8 logical link channels. .

SUMMARY OF THE INVENTION

[0008] An object of the present invention is to provide a technical solution which can support multi-service bandwidth allocation in an Ethernet Passive Optical Network (EPON).

[0009] According to one aspect of the invention, a method of service bandwidth allocation in an EPON system is provided, the EPON system comprising an OLT and a plurality of ONUs connected to the OLT, the method comprising the following steps: distinguishing, by ONUs, types of service flows and allocating different logical link channels based on the types of service flows; selecting, by the OLT, different bandwidth allocation methods and corresponding service scheduling for the logical link channels based on the types of service flows; performing, by ONUs, corresponding service scheduling according to the bandwidth allocation methods.

[0010] Preferably, the ONUs further identify user group properties of service flows. A user group is a set of service interfaces that have the same type of service flows and have the same service requirements. The ONUs further schedule the corresponding services based on the user group properties.

[0011] According to another aspect of the invention, a method of supporting multi-service bandwidth allocation in an optical network unit ONU is provided, comprising the following steps: the ONU distinguishes types of service flows; the ONU allocates different logical link channels and corresponding service scheduling based on the types of service flows.

[0012] Preferably, the optical network unit further identifies the user group properties of the service flows. The user group is a set of service interfaces that have the same type of service flows and have the same service requirements. The service requirements can be user bandwidth requirement or service application requirement; and the user group can be identified by Customer VLAN (CVLAN).

[0013] According to a further aspect of the invention, an optical network unit ONU that supports multi-service bandwidth allocation is provided, comprising classifying unit for distinguishing types of service flows; scheduling uint for allocating different logical link channels and corresponding service scheduling for data frames of different service flow types.

[0014] Preferably, the classifying unit further identifies user group properties of the service flows. The user group is a set of service interfaces that have the same type of service flows and have the same service requirements. The service requirements can be user bandwidth requirement or service application requirement, and the user group can be identified by Customer VLAN (CVLAN).

[0015] Preferably, the classifying unit distinguishes the types of service flows and identifies user groups according to the types of service interfaces, or according to relevant parameters in Ethernet data frames.

[0016] According to a yet further aspect of the invention, a method of multi-service bandwidth allocation in an optical line termination (OLT) is provided, comprising the following steps: selecting different bandwidth allocation methods for different logical link channels based on service types; and scheduling service flows of different logical link channels based on the selected bandwidth allocation methods.

[0017] Preferably, the OLT further configures mapping relationships between logical link channels of ONUs and corresponding types of service flows, and configures the mapping relationships between the types of service flows of ONUs and the user group properties.

[0018] According to a still further aspect of the invention, an optical line termination OLT that supports multi-service bandwidth allocation is provided, comprising configuring unit for selecting corresponding bandwidth allocation methods for logical link channels based on service types; scheduling unit for scheduling service flows of different logical link channels based on the selected bandwidth allocation methods.

[0019] Preferably, the configuring unit further configures mapping relationships between logical link channels of the ONUs and corresponding types of service flows or further configures mapping relationships between the types of service flows of ONUs and the user group properties.

[0020] By employing the technical solutions according to the present invention, operator can develop an EPON system with a guaranteed flexible QoS. And different logical link channels and corresponding bandwidth allocation methods are selected based on different service types. Typically, a principle of static bandwidth allocation is applicable for services which require fixed bandwidth, and a principle of dynamic bandwidth allocation is applicable for services which have various bandwidth requirements. After a total bandwidth corresponding to a logical link channel is allocated, the bandwidth can be further subdivided based on user groups so as to further meet the bandwidth or service requirements of different users. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The features, properties and advantages of the present invention will become more apparent through the following detailed description with reference to the drawings, where like or identical reference signs represent the same elements in the drawings, wherein

[0022] FIG. 1 illustrates an application diagram of a multi-service EPON system according to one preferred embodiment of the present invention.

[0023] FIG. 2 illustrates a schematic diagram of the structure of an ONU that supports multi-service application according to one preferred embodiment of the present invention.

[0024] FIG. 3 illustrates a schematic diagram of the structure of an OLT that supports multi-service application according to one preferred embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0025] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0026] FIG. 1 illustrates a schematic diagram of an application scenario according to one preferred embodiment of the present invention. The EPON system comprises an OLT, an Optical Distribution Network (ODN) and an ONU. The types of service flows that are possibly carried by the EPON system include Ethernet/IP service, voice service, TDM service and the like. The EPON system provides necessary QoS mechanism so as to guarantee that QoS of various priority services are provided at the uplink and downlink directions according to the Service Level Agreement (SLA), wherein:

[0027] the types of service interfaces at the user side of the ONU may include multiple 10/100M self-adaptive Ethernet interfaces that support data service, multiple POTS interfaces that support VoIP voice service, and multiple E1 interfaces that support TDM private line service etc. For a typical MDU/MTU-type ONU, the arrangement of the type and number of the above service interfaces varies with different application scenarios so as to support multiple users and multiple services.

[0028] In the embodiments of the present invention, the ONU in the EPON system allocates different logical link channels based on the types of service flows at the user side. In the figure, merely three logical link channels are illustrated, which are LLID1 , LLID2 and LLID3, respectively. In a different application scenario, an MDU/MTU may be designed into with as many as 8 logical link channels. For example, for VoIP voice service, all multi-path user data of the ONU whose service interface type is a POTS interface can be mapped to LLID1 . For video service, the multi-path user data of the ONU whose service interface type is an Ethernet interface can be mapped to LLID2; for Ethernet data service, all multi-path user data of the ONU whose service interface type is 10/100M Ethernet interface can be mapped to LLID3.

[0029] As an alternative method, the data from the 10/100M Ethernet interfaces is further distinguished by service flows, because for VoIP voice service or IPTV video service, the operator, when deploying, would usually stamp different priority identifiers (IEEE 802.1 D User Priority, or IP TOS and DSCP Priority Identifiers) for different services when the services are converted through devices such as home gateway or set top box. The ONU can distinguish these services locally based on the priority identifiers, and then map them to the corresponding logical link channels based on the service types. For example, VoIP voice service can be mapped to LLID1 ; video service can be mapped to LLID2; and Ethernet data service can be mapped to LLID3.

[0030] According to the embodiments of the present invention, different users at the ONU side have different service property requirements for their respective service interfaces. Taking the Ethernet interface as an example, different users may select different service bandwidths, which might be 10M data Internet, 20M data Internet and 30M data Internet ; while for the same interface bandwidth, the agreed service types may also be different. For example, for a 20M data interface, users may select 20M data, 10M data Internet plus 10M IPTV video application, or 20M video real-time monitoring, etc. A user group can be defined as a set of interfaces that have the same type of service flows and have the same service property requirements. The ONU identifies a user group with CVLAN, so as to facilitate a reasonable bandwidth allocation and service scheduling at the uplink and downlink directions by ONU and OLT.

[0031] The OLT selects different bandwidth allocation methods based on the logical link channels and can further schedule the downlink services corresponding to respective logical link channels by user groups, so as to meet specific service requirements of different users. For example, for the LLID1 of ONU carrying POTS type voice service, it employs a fixed bandwidth allocation method; for the LLID2 of ONU carrying data service, it may employ best-effort bandwidth allocation method, and for the LLID3 of ONU carrying real-time video service, it may employ bandwidth guaranteed bandwidth allocation method. After determining the bandwidth allocation methods for the above LLID1 , LLID2 and LLID3, OLT may further allocate different bandwidths according to the user group properties, or perform reasonable scheduling based on designated service characteristics.

[0032] Figure 2 is a schematic diagram of the structure of an ONU that supports multi-service application according to one preferred embodiment of the present invention. It comprises classifying unit 201 , scheduling units 202A, 202B and 202C, wherein

[0033] the classifying unit 201 can perform service flow classification on uplink based on the types of service interfaces, or relevant parameters in Ethernet frames. The selectable parameters may include: User Priority (IEEE 802.1 D), types of Ethernet frames (such as PPPoE, PWE3, MAC Control etc.), IP TOS/DSCP (Differentiated Service Code Point) Priority and the like, which are used to distinguish different service types such as VoIP voice service, data Internet service, real-time video service and etc.

[0034] According to one embodiment of the present invention, the classifying unit 201 can simply distinguish the service types based on the types of service interfaces, and then identify the user groups. For example, it classifies all data flows of POTS interface type from UNI 1 to UN I32 as VoIP voice service, all data flows of Ethernet interface type from UNI 33 to UNI 64 as data Internet service, and all data flows of Ethernet interface type from UNI 65 to UNI 96 as real-time video service. The classifying unit 201 further identifies the user group properties of the above service flows. The user group can be defined as a set of service interfaces that have the same type of service flows and have the same service requirements and identified by Customer VLAN (CVLAN). For example, some of the POTS interfaces (e.g., UNI 1 -UNI 12) are identified as CVLAN 11 and some other POTS interfaces (e.g., UNI 13-UNI 32) are identified as CVLAN 12 according to a certain special service characteristic of POTS interface.

[0035] According to one embodiment of the present invention, the classifying unit 201 can distinguish the service flows according to relevant parameters in data frames of Ethernet interfaces, and then identify the user groups. Taking the Ethernet interface as an example, different users may select different service bandwidths, which might be 10M data Internet , 20M data Internet ; differences might even exist in service types, for example for 20M data, the users can select 20M data, 10M data Internet plus 10M IPTV video application etc. For the service flows from the Ethernet interfaces, the operator, when deploying, would usually stamp different priority identifiers (IEEE 802.1 D User Priority, or IP TOS and DSCP Priority Identifier) for different services when the services are converted through devices such as home gateway or set top box . The ONU can distinguish these services locally based on the priority identifiers. The classifying unit 201 may further identify the user group properties of the service flows so as to facilitate a reasonable bandwidth allocation and scheduling by ONU and OLT Here, a user group can be defined as a set of interfaces that have the same type of service flows and have the same service property requirements, which is identified with CVLAN. For example, it can identify the VoIP voice services from Ethernet interfaces UNI 33 to UNI 64 as CVLAN 13 (with a 2M agreed service bandwidth), identify the video services from Ethernet interfaces UNI 33 to UNI 64 as CVLAN31 according to bandwidth requirements (with a 10M agreed service bandwidth), identify the data Internet services from Ethernet interfaces UNI 33 to UNI 64 as CVLAN 21 (with a 10M agreed service bandwidth) and CVLAN 22 (with a 20M agreed service bandwidth) according to bandwidth requirements, respectively, and identify the video services from Ethernet interfaces UNI 65 to UNI 96 as CVLAN 32 (with a 20M agreed service bandwidth) and CVLAN33 according to bandwidth requirements, respectively.

[0036] Scheduling units 202A, 202B and 202C allocate different logical link channels LLID1 , LLID2 and LLID3 for the data frames of the different types of service flows, and perform local service flow scheduling. Data frames of different service requirements will be first arranged into different queues. The scheduling units can perform the uplink service scheduling through strict priority weighted round robin (SP+WRR) so as to guarantee the service requirements.

[0037] According to one embodiment of the present invention, scheduling units 202A, 202B and 202C allocate different logical link channels based on service types. For example, scheduling unit 202A designates the POTS voice services from all service interfaces to LLID1 , scheduling unit 202B designates data Internet services to LLID2, scheduling unit 202C designates real-time video services to LLID3.

[0038] According to an embodiment of the present invention, scheduling units 202A, 202B and 202C further schedule the service flows according to user groups to meet their specific service property requirements. Taking queues #2A and #2B under the logical link channel LLID2 corresponding to data Internet service as an example, queue #2A corresponds to the user group CVLAN 21 with a 10M user bandwidth, and queue #2B corresponds to the user group CVLAN 22 with a 20M user bandwidth; thus, the user bandwidth of queue #2B is twice of that of the queue #2A. Accordingly, scheduling unit 202B performs the uplink service scheduling by SP+WRR, the access times of the scheduling unit 202B to queue #2B will be twice of queue #2A. For the same reasons, for queues #1 A and #1 B under LLID1 corresponding to voice service and queues #3A and #3B under LLID3 corresponding to real-time video service, scheduling units 202A and 202C schedule their respective service flows according to the characteristics of user groups to meet the requirements on user bandwidth or service application.

[0039] FIG. 3 illustrates a schematic diagram of the structure of an OLT that supports multi-service application according to one preferred embodiment of the present invention. It comprises configuring unit 301 and scheduling units 302A, 302B and 302C, wherein

[0040] Configuring unit 301 can first classify the services of ON Us and manage user identifications and service scheduling through OAM function extension. Here, it can configure the way in which ONU distinguishes the service flow types and further identify user groups. Different service flows correspond to different logical link channels. Thus, the operator may sign a Bandwidth Agreement with users based on "user group plus service type".

[0041] According to one embodiment of the present invention, here, configuring unit 301 may select different bandwidth allocation methods for different logical link channels based on the carried service types. For LLID1 of the ONU carrying POTS type voice services, it may employ a fixed bandwidth allocation method, such that the OLT sends a fixed number of Grants regularly to ONU, and allocates the bandwidth with a relatively short polling cycle and a relatively high Grant frequency. For LLID2 of ONU carrying data services, it may employ a best-effort bandwidth allocation method, such that when the bandwidths on EPON interfaces are not occupied by other services with higher priority, the ONU may use these bandwidths. For LLID3 of ONU carrying real-time video services, it may employ a bandwidth guaranteed bandwidth allocation method, such that the OLT sends Grant according to the reported information of ONU, and when the volume of actual service flows does not reach the guaranteed bandwidth, the dynamic bandwidth allocation (DBA) mechanism of OLT should be able to allocate the remaining bandwidth to other services.

[0042] Correspondingly, for downlink service scheduling, scheduling units 302A, 302B and 302C will schedule the service flows of different logical link channels according to the selected bandwidth allocation methods. The scheduling units map data packets of different service types to different logical link channels and the corresponding output queues, thereby guaranteeing the prioritization in handling key service data and meeting the requirement on infrastructure by different services. Scheduling unit 302A selects the fixed bandwidth allocation method for the voice services corresponding to LLID1 . Accordingly, even if there is no uplink fixed bandwidth service flow at ONU, OLT still sends to the ONU the Grant corresponding to the fixed bandwidth, so as to guarantee a shorter transmission delay for this type of service. Scheduling unit 302B selects the best-effort bandwidth allocation method for the data Internet services corresponding to logical link channel LLID2. Accordingly, OLT allocates Grant to the ONU according to REPORT information of all the online ONUs in the EPON system and the bandwidth occupation condition on EPON interfaces, while the system does not guarantee the amount of bandwidth obtained by the ONU or a special service of the ONU. Scheduling unit 302C ... for the real-time video services corresponding to logical link channel LLID3

[0043] According to one embodiment of the present invention, Scheduling units 302A, 302B and 302C may further schedule the downlink services corresponding to each LLID based on user groups, so as to meet the special service requirements of different users. For example:

[0044] The VoIP services from 32 POTS interfaces and some Ethernet interfaces are mapped to LLID1 . Thus, OLT allocates a total static bandwidth to the logical link channel, so as to meet its requirement on fixed bandwidth. Then, different bandwidths are allocated for the VoIP services of different user groups, or are reasonably scheduled according to the designated service characteristics.

[0045] The data Internet services from 32 designated Ethernet interfaces are mapped to LLID2. Thus, OLT allocates a total bandwidth to the LLID, so as to meet its requirement on the total bandwidth. Then, different bandwidths are allocated for the data Internet services of different user groups, or are reasonably scheduled according to the designated service characteristics.

[0046] The real-time video services from 32 designated Ethernet interfaces are mapped to LLID3. Thus, OLT allocates a total static bandwidth to the LLID, so as to meet its requirement on the fixed bandwidth. Then, different bandwidths are allocated for the video services of different user groups, or are reasonably scheduled according to the designated service characteristics.

[0047] Although the above description provides some embodiments for the present invention, it does not intend to limit the protection scope of the invention. Those skilled in the art may modify the embodiments in any way without departing from the scope and spirit of the present invention. Such modifications fall within the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1 . A method of service bandwidth allocation in an Ethernet Passive Optical Network (EPON) system, the system comprising an Optical Line Termination (OLT) and several Optical Network Units (ONU) connected to the OLT, the method including:

Step A. distinguishing, by ONUs, the types of service flows and allocating different logical link channels based on the types of service flows;

Step B. selecting, by the OLT, different bandwidth allocation methods and corresponding service scheduling for the logical link channels based on the types of service flows;

Step C. performing, by the ONUs, corresponding service scheduling according to the bandwidth allocation methods.

2. The method according to Claim 1 , wherein in said Step A, the ONUs identify user group properties of the service flows, wherein the user group is a set of service interfaces that have the same type of service flows and have the same service requirements, and in Step C, the OUNs schedule the corresponding services according to the user group properties.

3. The method according to Claim 2, wherein the ONUs use Customer VLAN (CVLAN) to identify the user group properties.

4. The method according to any one of Claims 2 to 3, wherein in said Step B, the OLT further schedules corresponding services according to the user group properties.

5. A method of supporting multi-service bandwidth allocation in an optical network unit, comprising:

Step A1 . distinguishing the types of service flows;

Step B1 . allocating different logical link channels and scheduling the services correspondingly according to the types of service flows.

6. The method according to Claim 5, wherein in said Step A1 , the optical network unit further identifies the user group properties of the service flows, where the user group is the set of service interfaces that have the same type of service flows and have the same service requirements.

7. The method according to Claim 6, wherein the service requirements can be requirement on user bandwidth or service application.

8. The method according to Claim 6, wherein in said Step B1 , the optical network unit maps the service flows to different physical queues according to the types of service flows and user group identifiers, thereby realizing the uplink service scheduling.

9. The method according to any one of Claims 6 to 8, wherein the optical network unit identifies user groups of the service flows with CVLAN.

10. An optical network unit supporting multi-service bandwidth allocation, comprising:

classifying unit, for distinguishing the types of service flows;

scheduling unit, for allocating different logical link channels and corresponding service scheduling for the data frames of said different service flow types.

11 . The optical network unit according to Claim 10, wherein the classifying unit further identifies user group properties of the service flows, where the user group is a set of service interfaces that have the same type of service flows and have the same service requirements.

12. The optical network unit according to Claim 11 , wherein the classifying unit distinguishes the types of service flows and identifies user groups according to the types of service interfaces.

13. The optical network unit according to Claim 11 , wherein the classifying unit distinguishes the types of service flows and identifies user groups according to the relevant parameters of Ethernet data frames.

14. The optical network unit according to Claim 11 , wherein the scheduling unit maps the service flows to different physical queues according to the types of service flows and user group identifiers, thereby realizing the uplink service scheduling.

15. The optical network unit according to any one of Claims 10 to 14, wherein the classifying unit identifies user groups with CVLAN.

16. A method of multi-service bandwidth allocation in an OLT, comprising: Step A2. selecting different bandwidth allocation methods for different logical link channels based on service types;

Step B2. scheduling the service flows of different logical link channels based on the selected bandwidth allocation methods.

17. The method according to Claim 16, wherein the method further includes: Step A2a. OLT further configures the mapping relationships between the logical link channels of optical network units and corresponding types of service flows.

18. The method according to Claim 17, wherein the method further includes: Step A2b. OLT further configures the mapping relationships between the types of service flows of optical network units and the user group properties.

19. The method according to any one of Claims 17 to 18, wherein in the Step B2, OLT further maps the service flows to different physical queues according to the types of service flows and user group identifiers, thereby realizing the downlink service scheduling.

20. An OLT supporting multi-service bandwidth allocation, comprising:

configuring unit, for selecting corresponding bandwidth allocation methods for logical link channels based on service types;

scheduling unit, for scheduling the service flows of different logical link channels based on the selected bandwidth allocation methods.

21 . The OLT according to Claim 20, wherein the configuring unit further configures the mapping relationships between the logical link channels of optical network units and corresponding types of service flows;

22. The OLT according to Claim 20, wherein the configuring unit further configures the mapping relationships between the types of service flows of optical network units and the user group properties.

23. The OLT according to any one of Claims 20 to 22, wherein the scheduling unit maps the service flows to different physical queues according to the types of service flows and user group identifiers, thereby realizing the downlink service scheduling.