Patent Application
20130315238
1. Field of the Invention
The present invention relates generally to multipoint control protocols and, more particularly, to a method and apparatus for extending multipoint control protocols to mixed media access systems.
2. Introduction
In a point-to-multipoint system such as an Ethernet passive optical network (EPON), a single optical line terminal (OLT) at a head end can be designed to communicate with a plurality of optical network units (ONUs) at various end nodes. This arrangement leverages a shared fiber optic plant by multiple networking nodes. Typically, the OLT broadcasts its transmissions in the downstream direction to all the ONUs. Each of the ONUs, on the other hand, transmit in the upstream direction to the OLT in a pre-assigned time slot.
In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the invention.
In various contexts where the high cost of optical fiber installation may not justify the extension of the optical fiber to the end network unit, mixed media access systems can result. For example, mixed media access systems such as PON-fed DSL and PON-fed Ethernet in telecom networks, Ethernet PON over coax (EPoC) in cable multiple systems operator (MSO) networks, PON-fed WiFi, WiMAX, 3G, LTE, etc. in wireless networks, and PON-fed power-line networks can be used. In these mixed media access systems, multiple management and quality of service (QoS) domains would exist.
In addressing mismatches at the domain boundaries, a medium-to-medium adaptor is provided that can interface with an upstream OLT in a PON domain and a downstream device in a non-PON domain. The medium-to-medium adaptor enables an implementation of end-to-end services across multiple QoS domains by passing all traffic with controlled delay and without contention. In one embodiment, the medium-to-medium adaptor can be configured to map a resource apportionment identifier in a header portion of the frame structure (e.g., preamble of an Ethernet frame or header of a GPON encapsulation method (GEM) or xGPON encapsulation (xGEM) frame) contained in network traffic communicated with an upstream OLT in a PON domain with a resource apportionment identifier in an Ethernet frame contained in network traffic communicated with a downstream device in a non-PON domain. The resource apportionment identifier is assigned to an end network unit by the OLT and enables the end network unit to report a status to the OLT and to grant bandwidth by the OLT to the end network unit. The communication of the resource apportionment identifier end-to-end across the PON domain and non-PON domain enables a control of the end-to-end QoS in the mixed media access system. As an example, in a mixed media access system that includes multiple medium-to-medium adaptors that each interface with an OLT in a PON domain and that support a non-PON wireless network domain (e.g., WiFi), control of the end-to-end QoS of a mobile station can be maintained even as the mobile station roams among the coverage areas of the multiple medium-to-medium adaptors.
Here, it should be noted that the PON domain can represent an EPON such as that defined by IEEE 802.3, GPON, BPON, xGPON, or NGPON defined by ITU-T, or the like. In general, the advantage of the PON is that it allows sharing of the fiber optic plant by multiple network nodes. In the downstream direction, OLT 110 is configured to broadcast frames containing packets to the end network units that are responsible for extracting the particular packets that are destined for that location, while in the upstream direction the end network units are designed to transmit in a way to avoid collisions between the packets using, for example, a time division multiple access (TDMA) communication protocol.
In a mixed media access system, adaptor node 130-n is configured to interface with a PON domain and a non-PON domain.
In providing an interface between a PON domain and a non-PON domain, adaptor node 220 can be configured to include medium-to-medium adaptor 221. As illustrated, adaptor node 220 includes PON physical layer device (PHY) 222 and PON media access control (MAC) 226 that are configured to operate with PON PHY 212 and PON MAC 214, respectively, in OLT 210. Adaptor node 220 also includes non-PON PHY 224 and non-PON MAC 228 that are configured to operate with non-PON PHY 232 and non-PON MAC 234, respectively, in end network unit 230. Here, it should be noted that non-PON MAC 228 in medium-to-medium adaptor 221 is optionally included depending on whether or not communication in the non-PON domain uses a non-PON MAC to facilitate controls such as addressing and non-PON channel access. For example, where the non-PON domain includes a WiFi link, medium-to-medium adaptor 221 can be configured to include a complementary 802.11 MAC to operate with an 802.11 MAC in end network unit 230. As would be appreciated, the necessity and/or particular type of non-PON MAC used in the non-PON domain would be implementation dependent.
As further illustrated in
Extended PON protocols 238 in end network unit 230 is designed to cooperate with extended PON protocols 216 in OLT 210 in providing end-to-end services across multiple management and QoS domains. As illustrated in
The operation of adaptor node 220 in facilitating the provision of end-to-end services is described in greater detail below. Here, it should be noted that PON MAC 236 and extended PON protocols 238 in end network unit 230 would be unaware of the particular non-PON medium on which it operates.
Prior to describing the operation of adaptor node 220 in greater detail, it should be noted that the principles of the present invention are not confined to an end-to-end link having a single intermediate adaptor node. As illustrated in
Adaptor node 400 also includes medium-to-medium adaptor 410. In general, medium-to-medium adaptor 410 is designed to extend a multi-point control protocol over the non-PON domain and provides a data bridge between upstream and downstream domains. In the example embodiment illustrated in
As further illustrated in
In one example applied to IEEE 802.3 EPON, the bandwidth assignment message is represented by the EPON GATE message that identifies a timeslot based on a start time and length, while the status report message is represented by the EPON REPORT message. In another example applied to ITU-T GPON, the bandwidth assignment message is enabled using the US BW Map in the header of the GEM/XGEM frame, which identifies a timeslot based on a start time and an end time, while the status report message is enabled through the request for an upstream transmission slot using either the upstream Ind field in the PLOu block or the DBRu field.
In ensuring that intermediate adaptor node 400 passes traffic in scheduled transmission windows to avoid collisions or contention within the network, the bandwidth assignment process within MAC control 413 can control the upstream transmission of data that resides in a transmission queue, which holds traffic received from a downstream device in a non-PON domain. As would be appreciated, the transmission queue can also include message traffic (e.g., REPORT messages) that is generated by intermediate adaptor node 400 and is to be delivered upstream to the OLT.
To facilitate the transmission of data in scheduled transmission windows, the intermediate adaptor node is designed to pass traffic with controlled delays. For example, during the autodiscovery phase during which time the OLT detects newly connected end network units and learns the round-trip delays of those end network units, the intermediate adaptor node can be configured to pass messages after a delay of a consistent period of time. This consistent period of time can be defined to be a delay period that would be sufficient to accommodate processing by the adaptor node.
Through an introduction of a controlled delay period by the intermediate adaptor node, the OLT can accurately determine the round-trip delay between the OLT and the end network unit. Such accuracy is an important factor in enabling the OLT in scheduling bandwidth assignments to the various end network units. For example, if the DBA agent in the OLT desires to receive data from an end network unit at time t, then the bandwidth assignment message would be sent to the end network unit exactly at time t−RTT, where RTT is the round-trip time to the end network unit (including any controlled delays introduced by the intermediate adaptor node(s)).
In one application, synchronization mapping module can be used to facilitate a full-duplex/half-duplex adaptation where the PON domain operates in a full duplex mode and the non-PON domain operates in a half duplex mode. Here, the OLT, adaptor node and end network unit can provide unified management of the upstream and downstream traffic. More specifically, the extended PON protocol can be used to schedule upstream transmission by the end network unit and downstream transmission by the medium-to-medium adaptor to coincide with the time-slots in the non-PON domain.
Another example of processing by medium-to-medium adaptor 500 is the encryption adaptation where a first form of encryption is used in the PON domain and a second form of encryption is used in the non-PON domain. In providing an interface between the PON domain and the non-PON domain, medium-to-medium adaptor 500 can decrypt PON traffic to produce unencrypted traffic that is processed by the medium-to-medium adaptor, prior to encrypting traffic to be sent over the non-PON domain. In one embodiment, the traffic encrypted for the non-PON domain has previously been encrypted using PON encryption. As would be appreciated, medium-to-medium adaptor can be configured to address mismatches between capacity, latency, bit error rate (BER), forward error correction (FEC), security, etc. between the PON domain and non-PON domain boundaries.
As has been described, a medium-to-medium adaptor contained in an intermediate adaptor node can be configured to perform various adaptations in providing an interface between a PON domain and a non-PON domain. As would be appreciated, the specific types of adaptations would be dependent on the particular implementation of the non-PON domain. Notwithstanding these various potential adaptations, the medium-to-medium adaptor is designed to implement end-to-end services across multiple management and QoS domains. To facilitate this implementation of end-to-end services across multiple management and QoS domains, a resource apportionment identifier (e.g., LLID or AllocID) that is assigned by an OLT to an end network unit is communicated end-to-end across the PON domain and non-PON domain.
In one embodiment, the medium-to-medium adaptor can be configured to map a resource apportionment identifier in a header portion of the frame structure contained in network traffic communicated with OLT 610 in a PON domain to a resource apportionment identifier in an Ethernet frame contained in network traffic communicated with end network unit 630 in a non-PON domain. This process of mapping of the resource apportionment identifier is designed to enable the end-to-end communication of the resource apportion identifier between the OLT and the end network unit, thereby enabling end-to-end service implementation.
In mapping traffic between the PON domain and the non-PON domain, the header portion of the PON domain traffic is removed. As illustrated, the resource apportionment identifier that is needed for implementation of the end-to-end service is extracted from the header portion of the PON domain traffic, and inserted into the frame portion of the non-PON domain traffic. In the illustrated example, the resource apportionment identifier can be inserted into a 16-bit portion of the VLAN field of the Ethernet frame. As would be appreciated, the principles of the present invention are not limited to the insertion of the resource apportionment identifier into a VLAN field of the Ethernet frame. In other embodiments, the resource apportionment identifier can be inserted into another defined field of the Ethernet frame or at a defined offset position within the data portion of the Ethernet frame.
Regardless of the location within the Ethernet frame at which the resource apportionment identifier is inserted, its inclusion within the Ethernet frame enables the resource apportionment identifier to be communicated over the non-PON domain for receipt by the end network unit. At the receiving end network unit, the Ethernet frame can be parsed and the resource apportionment identifier extracted for use by the PON MAC and extended PON protocols at the end network unit.
To further illustrate the mapping process of a resource apportionment identifier by an intermediate adaptor node, reference is now made to the flowchart of
Next, at step 806, the extracted resource apportionment identifier is inserted into an Ethernet frame in a defined field or at a defined offset location of the Ethernet frame. The particular field or location at which the resource apportionment identifier is inserted would be implementation dependent. Finally, at step 808, the Ethernet frame that contains the resource apportionment identifier is then transmitted, via a non-PON PHY of the intermediate adaptor node, to a downstream non-PON domain.
It is a feature of the present invention that the mapping of a resource apportionment identifier from a header portion to the frame portion itself enables the resource apportionment identifier to be carried over the non-PON domain for use by the end network unit. This enables the establishment of an end-to-end emulation of a point-to-point service that crosses multiple domains. In one embodiment, the non-PON PHY in the non-PON domain can be enhanced to recognize Ethernet frames with additional tags or fields that are used for the communication of a resource apportionment identifier.
The communication of the resource apportionment identifier over the non-PON domain enables a PON point-to-point multipoint protocol to be extended to provide management and control of a hybrid network having a PON domain and a non-PON domain. To illustrate the application of such management and control over a hybrid network, consider an example application to a hybrid network having an IEEE 802.11 non-PON domain.
When end network unit 940 enters into the range of adaptor node 930-1 in the hybrid network, end network unit 940 would first establish a WiFi connection with adaptor node 930-1 via communication with the 802.11 non-PON PHY and the 802.11 non-PON MAC in adaptor node 930-1. Once the WiFi connection is established between adaptor node 930-1 and end network unit 940, end network unit 940 can then register with OLT 910 via adaptor node 930-1 at step 1002. In this process, end network unit would respond to an autodiscovery process that is initiated by OLT 910 using a discovery GATE message. After end network unit 940 sets its local clock to the timestamp received in the discovery GATE message, end network unit 940 would then transmit a REGISTER_REQ message after waiting a random delay period following the start time of the initialization slot indicated by the discovery GATE message. The transmitted message would include the MAC address of end network unit 940 as well as the timestamp that represents the time that the REGISTER_REQ message was sent by end network unit 940. The timestamp enables OLT 910 to determine the round-trip time from OLT 910 to end network unit 940. Upon parsing and verifying the REGISTER_REQ message, OLT 910 would then issue a REGISTER message that contained the resource apportionment identifier that is assigned to end network unit 940.
After end network unit 940 has registered with OLT 910, end network unit 940 can then communicate with OLT 910 using the assigned resource apportionment identifier at step 1004. In this process, normal GATE and REPORT messages can be communicated between OLT 910 and end network unit 940 via adaptor node 930-1 using the resource apportionment identifier. This communication over the hybrid network that includes a PON domain and a non-PON domain is enabled by adaptor node 930-1, which facilitates the interface between the PON domain and non-PON domain in passing traffic between OLT 910 and end network unit 940. In one embodiment, OLT 910 would continue to monitor and adjust the round-trip time value for a connection to end network unit 940 via adaptor node 930-1 to ensure that synchronization through the PON domain is maintained as end network unit 940 moves within the range of adaptor node 930-1.
As end network unit 940 moves within the coverage area of hybrid network 900, end network unit can associate itself with a new wireless access point at step 1004. This process is illustrated in
The change in association of end network unit 940 from adaptor node 930-1 to adaptor node 930-2 would be facilitated by the 802.11 non-PON PHYs and 802.11 non-PON MACs contained in end network unit 940 and adaptor node 930-2. Significantly, the change in association of end network unit 940 from adaptor node 930-1 to adaptor node 930-2 would not require re-registration with OLT 910. Here, it is a feature of the present invention that the communication at step 1006 between end network unit 940 and OLT 910 would be facilitated using the same resource apportionment identifier that was obtained through the registration of end network unit 940 with OLT 910 via adaptor node 930-1. To facilitate the communication of end network unit 940 with OLT 910 via adaptor node 930-2, OLT 910 would again continue to monitor and adjust the round-trip time value for a connection to end network unit 940 via adaptor node 930-2 to ensure that synchronization through the PON domain is maintained as end network unit 940 moves within the range of adaptor node 930-2. Here, it should be noted that the use of the same resource apportionment identifier in communication with OLT via adaptor node 930-1 as well as adaptor node 930-2, enables end-to-end QoS to be controlled as end network unit 940 roams within the various coverage areas of the hybrid network.
As would be appreciated, the particular form of control over end-to-end services would be implementation dependent. What is significant is that such control over end-to-end services can be extended across various forms of hybrid networks.
In one embodiment, the extension of the multipoint control protocol can enable power management in promoting energy efficiency. For example, where non-PON domain network devices support low-power modes of operation, the management of the low-power modes of operation can be managed by the OLT using the resource apportionment identifier.
Another embodiment of the invention may provide a machine and/or computer readable storage and/or medium, having stored thereon, a machine code and/or a computer program having at least one code section executable by a machine and/or a computer, thereby causing the machine and/or computer to perform the steps as described herein.
These and other aspects of the present invention will become apparent to those skilled in the art by a review of the preceding detailed description. Although a number of salient features of the present invention have been described above, the invention is capable of other embodiments and of being practiced and carried out in various ways that would be apparent to one of ordinary skill in the art after reading the disclosed invention, therefore the above description should not be considered to be exclusive of these other embodiments. Also, it is to be understood that the phraseology and terminology employed herein are for the purposes of description and should not be regarded as limiting.
| Number | Date | Country | |
|---|---|---|---|
| 61651726 | May 2012 | US |
