KR100957046B1 - Ethernet Frame structure and Ethernet Frame Switching Method using the same for virtual port-based switching in GEM mode of Gigabit PON - Google Patents

Abstract

Disclosed are an Ethernet frame structure for virtual port-based switching in a GON mode of a Gigabit passive optical subscriber network (GPON), and a switching method based thereon. The Ethernet frame switching method of the Ethernet switch for the Ethernet frame transmitted from the OLT in the GEM mode of the Gigabit passive optical subscriber network (GPON) of the present invention, the OEM GEM port ID ( And inserting the port ID information into the Ethernet switch, and creating a virtual port based on the GEM port ID information inserted in the Ethernet frame, and converting the Ethernet port based on the MAC (Media Access Control) address learned for each virtual port. And switching the frames, thereby switching the Ethernet frames based on the virtual ports configured by the Ethernet switches.

GPON, GEM, Virtual, Virtual, Port, GEM Port, Switching, Ethernet, Frame, ONU, OLT

Description

Ethernet frame structure and Ethernet frame switching method using the same for virtual port-based switching in GEM mode of Gigabit PON}

The present invention relates to a Gigabit-capable Passive Optical Network (GPON), and more particularly, in the case of performing data communication in the GON (GPON Encapsulation Mode) mode in a Gigabit Passive Optical Subscriber Network (GPON) A method of exchanging Port ID information with an Ethernet switch and a method of configuring a virtual port in a switch are provided.

In general, a passive optical network (PON) is a network in which an access node and a subscriber device located in a telephone company have a point-to-multipoint topology. It is in the spotlight as a subscriber network. Passive optical subscriber networks (PONs) are classified into Fiber To The Curb (FTTC), Fiber To The Building (FTTB), and Fiber To The Home (FTTH), depending on the location of the network termination device.

1 is a view showing an access network of a general passive optical subscriber network (PON) structure.

As shown, a passive optical subscriber network (PON) includes an optical line terminal (OLT) 10 and a plurality of optical network units (ONUs) located in a central office. 30,..., 38 are connected by using '1'N' Optical Distribution Network (ODN) 20 to form a distributed topology of a tree structure.

At this time, the optical path terminator (OLT) 10 is a service for providing a corresponding content service to be provided to the optical subscriber network device (ONU) (30, ..., 38) through the optical fiber terminator (OLT) (10) It is connected with the providing node 50. The service providing node 50 may be a TDM / PSTN (Time Division Multiplexing / Public Switching Telephone Network) network, an Asynchronous Transfer Mode (ATM) network, an Internet Protocol (IP) network, a Video / Audio network, or the like. It is composed.

The optical subscriber network device (ONU) 30,..., 38 also provides content services such as voice, data, and video provided from the optical fiber terminator (OLT) 10. Performs a function provided to the subscriber station (40, 48).

FIG. 2 is a diagram illustrating an example of data transmission between an optical path termination device (OLT) and an optical subscriber network device (ONU) in a typical passive optical subscriber network (PON).

In general, a passive optical subscriber network (PON) comprises one optical fiber terminator (OLT) and a plurality of optical subscriber network devices (ONU). 2 shows an example in which three optical subscriber network devices (ONUs) 30a, 32a, and 34a are connected to one optical path terminator (OLT) 10a.

Referring to FIG. 2, the optical path terminator (OLT) 10a transmits the downward frame 12a downward toward the passive optical splitter (ODN) 20a, and the transmitted downward frame 12a is the passive optical splitter (OA). It transmits to the subscriber network devices (ONUs) 30a, 32a, and 34a through the ODN 20a. Accordingly, the optical subscriber network devices (ONUs) 30a, 32a, 34a receive the downlink frame 12a transmitted from the optical path terminator (OLT) 10a via the passive optical splitter (ODN) 20a. After filtering, the controller selects a data frame corresponding to itself and provides the data frame to each end user terminal 40a, 42a, 44a connected thereto. Here, the end user terminals 40a, 42a, and 44a refer to various types of subscriber network terminators that can be used in a passive optical subscriber network (PON) including NT (Network Terminal).

On the other hand, the uplink frames 41a, 43a, and 45a provided from the end user terminals 40a, 42a, and 44a are passive optical splitters (ODNs) by the respective optical subscriber network devices (ONUs) 30a, 32a, and 34a. It is transmitted to the optical path terminator (OLT) 10a via 20a.

In the passive optical subscriber network (PON) shown in FIG. 2, Asynchronous Transfer Mode-Passive Optical Networks (ATM-PON) was first developed and standardized. This is described in ITU-T G.982, ITU-T G.983 and ITU-T G.983.3, documented in the International Telecommunication Union-Telecommunication section (ITU-T). Next, Ethernet PON (EPON) is standardized by the IEEE802.3ah Ethernet First Mile (EMF) standardization organization, and data transmission is based on Ethernet.

In general, in the asynchronous transmission mode-passive optical subscriber network (ATM-PON), ATM cells having a size of 53 bytes are transmitted up / down in the form of a data frame in which a predetermined size is combined. In the optical subscriber network (PON) structure, the optical fiber terminator (OLT) 10a properly inserts downlink cells to be distributed to each of the optical subscriber network devices (ONUs) 30a, 32a, and 34a in the downward frame. In addition, in the case of uplink transmission, the OLT 10a accesses data transmitted from the optical subscriber network devices (ONUs) 30a, 32a, and 34a in a time division multiplexing (TDM) manner. At this time, since the passive optical splitter (ODN) 20a connected between the optical path terminator (OLT) and the optical subscriber network devices (ONUs) 30a, 32a, and 34a is a passive element, the optical path terminator (OLT) 10a prevents data from colliding in the passive optical splitter (ODN) 20a, which is a passive element, using a virtual distance correction algorithm called ranging. In addition, when transmitting downlink data from the optical path terminator (OLT) 10a to the optical subscriber network devices (ONUs) 30a, 32a, and 34a, the optical path termination device (OLT) and the optical subscriber network devices (ONUs). (30a, 32a, 34a) Each other is supposed to send and receive encryption keys for encryption and OAM (Operations, Administration and Maintenance) messages for maintenance. To this end, up / down frames have corresponding data fields in dedicated ATM cells or general ATM cells that can send and receive messages at regular intervals.

As such, the standardized ATM-PON operates based on ATM, and the EPON operates based on Ethernet. On the other hand, Gigabit-capable Passive Optical Network (GPON) is not only a cell-based transmission method (aka ATM mode) that handles ATM services, but also Time Division Multiplex (TDM) and Ethernet. It supports GEM (GPON Encapsulation Method) method (aka GEM mode) that processes variable length packets like service. In this case, the ATM mode maps and transmits transmission data to a G-PON Transmission Convergence (GTC) frame on a cell basis, and the GEM mode maps and transmits transmission data to a GTC frame on a GEM frame basis.

Since the GPON is a point-to-multipoint topology of a tree structure, all packets transmitted by the optical fiber terminator (OLT) 10a should be broadcast in principle, and the optical subscriber network device receiving the broadcasted packets. The ONUs 30a, 32a, and 34a select and receive a desired packet through filtering.

On the contrary, since a plurality of optical subscriber network devices (ONUs) 30a, 32a, and 34a share an uplink channel, a bandwidth allocation algorithm is needed to efficiently use network resources.

In the GEM mode of a gigabit passive optical subscriber network (GPON), for traffic multiplexing, 4,096 unique port identifiers (Port IDs) are included in the header of the GEM frame and transmitted. An individual port ID is assigned for each unicast or multicast channel set between the OLT and the ONU. The downlink traffic transmitted from the OLT to the ONU is received by comparing the Port ID information included in the header of the GEM frame at the ONU.Upstream traffic transmitted from the ONU to the OLT is determined by the OLT. Multiplexing is performed.

3 is a diagram illustrating a detailed structure of a GEM (GPON Encapsulation Mode) frame generally used in GPON.

As shown, a GPON Encapsulation Mode (GEM) frame typically consists of a GPON Encapsulation Mode (GEM) header 50 and a GPON Encapsulation Mode (GEM) frame 60.

Here, the GEM header 50 is a payload length indicator (PLI) 51 indicating the length information of the payload, a port indicating the ID (Port ID_) information of a port for identifying traffic in order to provide traffic multiplexing. Port ID (53), Payload Type Indicator (PTI) 55 indicating payload type information, HEC (Header Error Control) 57 for error detection and correction of headers, and fragmented payload information. It comprises a fragmentation payload (59) indicating a.

In this case, the PLI 51 is 12 bits, the Port ID 53 is 12 bits, the PTI 55 is 3 bits, the HEC 57 is 13 bits, and the fragmentation payload 59 is used. Is composed of L bits.

4 is a diagram illustrating a protocol stack structure of a typical GPON.

As shown, the protocol stack of the GPON includes a protocol layer 70 for interfacing with a higher layer, a G-PON Transmission Convergence (GTC) layer 80, and a GPON Physical Media dependent (GPM) layer 90. It is configured by.

The protocol layer 70 includes an Asynchronous Transfer Mode (ATM) client 71, an ONT Management Control Interface (OMCI) 72, a GEM client 73, and a Physical Layer Operation Administration Maintenance (PLOAM) module. .

The GPON protocol having such a configuration multiplexes the upper frame to the GTC frame in the GTC layer 80, among which the ATM client 71 supports the ATM mode transmission method, the GEM client 73 GEM It supports mode transmission method.

Meanwhile, the OLT of the Gigabit Passive Optical Subscriber Network (GPON) transmits a data frame to the GEM client 73 through the GTC layer 80, and an Ethernet switch or NP (Network Processor) serves as the GEM client 73. Do this.

In GEM mode of Gigabit Passive Optical Subscriber Network (GPON), when the OLT is connected with an Ethernet switch (or NP), the Ethernet switch must perform virtual port based switching, not physical port based switching. In order to configure virtual ports, OLT needs to provide GEM port ID information to Ethernet switch (or NP), and switch (or NP) configures and switches virtual ports using GEM port ID information. Consideration should be given to implementation.

An object of the present invention for solving the above problems, a method for providing GEM port ID information for switching transmission of data frames to the Ethernet switch in the GPON Encapsulation Mode (GEM) mode of a gigabit passive optical subscriber network (GPON) To provide.

Another object of the present invention is to provide a method for configuring a virtual port by an Ethernet switch using virtual ID information of a provided GEM port and performing virtual port based switching.

An Ethernet frame structure for virtual port-based switching of an Ethernet switch in a GPON Encapsulation Mode (GEM) mode of a gigabit passive optical subscriber network (GPON) according to an embodiment of the present invention for achieving the above object, the Ethernet frame of the A preamble disposed at a front end and including GEM Port ID information corresponding to the virtual port required for the switching operation of the Ethernet switch; And a data frame disposed at a rear end of the Ethernet frame and including actual data.

The preamble includes a Start of Port-ID Delimiter (SPD) (0xd5) (2 bytes), GEM port ID information (12 bits), and CRC8 (Cyclic Redundancy Checking 8) (1 byte).

The GEM port ID information indicates unicast and multicast channel information set between the OLT and ONU for the Ethernet frame.

The data frame includes destination address (D) (6 bytes), source address (SA) (6 bytes), packet type and length information (Type / Length) (2 bytes), and data ( The data is composed of 46 to 1500 bytes), and frame transmission error detection information (Frame Check Sequence: FCS) (4 bytes).

On the other hand, the Ethernet frame switching method of the Ethernet switch for the Ethernet frame transmitted from the OLT in the GPON Encapsulation Mode (GEM) mode of the gigabit passive optical subscriber network (GPON) according to an embodiment of the present invention for achieving the above object (a) the OLT inserting GEM port ID information necessary for the switching operation of the Ethernet switch in the preamble of the Ethernet frame and transmitting the inserted GEM port ID information to the Ethernet switch; (b) configuring, by the Ethernet switch, a virtual port based on the GEM port ID information inserted into the Ethernet frame and learning a MAC address; And (c) the Ethernet switch performing switching based on the learned MAC address for each port, and transmitting virtual port information to be output in the preamble of the Ethernet frame to the OLT.

The step (a) may include: performing, by the OLT, a Gigabit Media Independent Interface (GMII) interface matching with the Ethernet switch in an initial state; When receiving a GEM frame from an ONU, inserting the GEM port ID information included in a header of a GEM frame into a preamble of the Ethernet frame; And transmitting the Ethernet frame into which the GEM port ID information is inserted, to the Ethernet switch.

The step (b) may include: detecting, by the Ethernet switch, the GEM port ID information included in the preamble of the Ethernet frame by receiving the Ethernet frame transmitted from the OLT; Generating the virtual port for each detected GEM port ID; And learning the source MAC address of the Ethernet frame for each of the generated virtual ports.

The step (c) may include: performing, by the Ethernet switch, switching based on the MAC address learned for each port; And when the Ethernet switch transmits the frame to the OLT, including the GEM port ID information corresponding to the output port in the preamble of the Ethernet frame and transmitting the frame to the OLT.

The Ethernet frame switching method of the present embodiment further includes the step of configuring, storing and managing a table including the ONU and the GEM port ID information by the Ethernet switch for each virtual shaft.

In the virtual port generation step, the Ethernet switch assigns the virtual port for each Alloc ID (Allocation Identifier) information that refers to a transmission container (T-CONT) in the ONU based on the detected GEM port ID information. It further includes.

The Ethernet frame includes a data frame including actual data for transmission to the ONU together with the preamble, wherein the data frame includes destination address (DA) and source address (SA). And packet type and length information (Type / Length), and frame transmission error detection information (Frame Check Sequence: FCS).

According to the present invention, when OLT transmits a GEM frame to an Ethernet switch (or NP) in a GEM mode of a passive optical subscriber network (GPON), GEM port ID information is inserted into a preamble of an Ethernet frame. By transmitting and configuring the virtual port based on the transmitted GEM port ID information, the Ethernet switch receiving the switch can perform the switching process for the Ethernet frame based on the virtual port configured by the Ethernet switch.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same elements in the figures are represented by the same numerals wherever possible. In addition, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

5 is a diagram illustrating an example of matching between an OLT and an Ethernet switch applied to the present invention according to a preferred embodiment of the present invention. In the present invention, GMII (Gigabit Media Independent Interface) is used for matching between the OLT and the Ethernet switch.

As shown, the Ethernet switch or Network Processor (NP) 100 may include a link aggregation function, a virtual port ID switch function, an Ethernet (Quality of Signal) function, and a network packet load. Rate Limiting (Limit Limiting) function, and the multicast Multicast Internet Group Management Protocol (IGMP) function that controls the network load by multi-cat packet filtering.

The GPON OLT Controller 210, which is provided in a Gigabit passive optical network end point (GPON OLT) 210, has a multi-physical layer emulation function and a passive optical subscriber network (PON Aware QoS) function that provides QoS. , Service Level Agreement (SLA) Enforcer, Layer-2 Classifier, etc.

In the present invention, the Ethernet switch 100 and the GPON OLT Controller 210 of the optical path termination device (OLT) are matched through a Gigabit Media Independent Interface (GMII) 300 to transmit and receive Ethernet frames.

6 is a diagram illustrating an example of a configuration of an Ethernet frame format including GEM port ID information according to an embodiment of the present invention.

As shown, the Ethernet frame consists of a preamble 400 and a data frame 500.

In general, the preamble 400 of the Ethernet frame is for synchronization with each other when a packet starts to be transmitted and received. The preamble 400 includes a 0x55 value corresponding to 7 bytes and a 0xd5 value corresponding to the last 8 bytes. In an embodiment of the present invention, when an Ethernet frame is transmitted through GMII matching between an OLT and an Ethernet switch, a method of providing GEM Port ID information is required.

Therefore, in order to provide GEM port ID information without changing the data frame 500 in the Ethernet frame composed of the preamble 400 and the data frame 500, the preamble 400 must be newly defined.

The Ethernet preamble 400 according to the present invention, which is newly defined according to such a requirement, is shown in FIG. 6, as shown in FIG. , GEM Port ID information 440, and Cyclic Redundancy Checking 8 (CRC8) 450. Here, 0x5555 (410) is 2 bytes, SPD (0xd5) 420 is 1 byte, 0x55555 (430) is 20 bits, Port ID (440) is 12 bits, and CRC8 450 is 1 byte It consists of.

In addition, the data frame 500 of the Ethernet frame includes destination address (D) (510), source address (SA) 520, and packet type and length information (Type / Length) 530. , Actual data 540, and frame transmission error detection information (Frame Check Sequence: FCS) 550. Here, the DA 510 is composed of 6 bytes, the SA 520 is 6 bytes, the Type / Length 530 is 2 bytes, the data 540 is 46 to 1500 bytes, and the FCS 550 is 4 bytes.

The GEM port ID information 440 included in the Ethernet preamble 400 according to an embodiment of the present invention is provided by the OLT and the Ethernet switch when the Ethernet frame is transmitted, and is defined only in a matching section between the OLT and the switch.

FIG. 7 is a diagram illustrating a virtual port configuration table of an Ethernet switch using GEM Port ID information according to an embodiment of the present invention.

As shown in FIG. 7A, the Ethernet switch 100 in FIG. 6 configures a virtual port ID 630 based on the GEM Port ID 620 provided from the OLT. After that, switching is performed based on the configured virtual port 630. The method for configuring the virtual port 630 is to allocate the virtual port 630 for each ONU 610 based on the provided GEM port ID information 620 and to the GEM port ID information 620 assigned for each ONU 610. Accordingly, the MAC address 640 is learned from the virtual input port of the switch, virtual port based switching is performed, and the GEM port ID information 620 is included in the Ethernet frame at the virtual output port and transmitted to the OLT.

In this embodiment, as shown in FIG. 7A, the virtual port 630 may be allocated and managed for each ONU 610, and as shown in FIG. 7B, a transmission container (T-CONT) in the ONU 710. It may be allocated and managed for each Alloc ID (Allocation Identifier) 740. In addition, some allocate a virtual port 730 for each T-CONT, some allocate a virtual port 730 for each ONU 710, and include in the GEM port ID information 720 allocated for each Alloc ID 740. Virtual port-based switching may be performed according to the unicast or multicast port ID information. To configure the virtual port 730 and provide switching for each T-CONT, the virtual port is learned by learning media access control (MAC) address information, virtual local area network (VLAN) information, and priority information (750). After the configuration, and performing virtual port-based switching, the GEM port ID information is included on the basis of MAC address information, VLAN information, and Priority information 750, and transmitted to the OLT.

8 is a flowchart illustrating a GEM port ID information providing and a switching method based on the GEM port ID information according to an embodiment of the present invention.

As shown, first, the OLT 200 having the GPON OLT Controller 210 of FIG. 5 performs GMII interface matching with the Ethernet switch 100 in an initialization process (S110).

Subsequently, when the GEM frame including the GEM port ID information allocated when setting the channel between the OLT 200 and the ONUs is upwardly transmitted from the ONU, the OLT 200 transmits the GEM port ID information to the preamble of the Ethernet frame (400 in FIG. 6). Insert it into (S120). After inserting the GEM port ID information into the preamble 400 of the Ethernet frame, the OLT 200 transmits the Ethernet frame into which the GEM port ID information is inserted (S130).

The Ethernet switch 100 receives the Ethernet frame transmitted from the OLT 200, and detects GEM port ID information included in the preamble of the Ethernet frame (S140). The Ethernet switch 100 generates a virtual port ID based on the detected GEM port ID information (S150). For simplicity, the Ethernet switch 100 may configure a table including virtual port ONU information, GEM port ID information, and MAC address information (S160).

Accordingly, the Ethernet switch 100 switches the Ethernet frame based on the virtual port (S170).

The Ethernet switch 100 inserts the GEM port ID information related to the output port (S180) and transmits the switched Ethernet frame to the OLT 200 (S190).

In the foregoing, certain preferred embodiments of the present invention have been shown and described. However, the present invention is not limited to the above-described embodiments, and any person having ordinary skill in the art to which the present invention pertains may make various modifications and equivalents without departing from the gist of the present invention attached to the claims. Other implementations may be possible. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

1 is a view showing an access network of a general passive optical subscriber network (PON) structure.

FIG. 2 is a diagram illustrating an example of data transmission between an optical path termination device (OLT) and an optical subscriber network device (ONU) in a typical passive optical subscriber network (PON).

3 is a diagram illustrating a detailed structure of a GEM (GPON Encapsulation Mode) frame generally used in GPON.

4 is a diagram illustrating a protocol stack structure of a typical GPON.

5 is a diagram illustrating an example of matching between an OLT and an Ethernet switch applied to the present invention according to a preferred embodiment of the present invention.

6 is a diagram illustrating an example of a configuration of an Ethernet frame format including GEM port ID information according to an embodiment of the present invention.

FIG. 7 is a diagram illustrating a virtual port configuration table of an Ethernet switch using GEM Port ID information according to an embodiment of the present invention.

8 is a flowchart illustrating a GEM port ID information providing and a switching method based on the GEM port ID information according to an embodiment of the present invention.

Claims (12)

In an Ethernet frame structure for virtual port based switching of an Ethernet switch in a GPON Encapsulation Mode (GEM) mode of a Gigabit-capable Passive Optical Network (GPON), A preamble disposed in front of the Ethernet frame and including GEM Port ID information necessary for a switching operation of the Ethernet switch; And An Ethernet frame structure disposed at a rear end of the Ethernet frame and including a data frame including actual data to be switched according to the virtual port generated by the Ethernet switch based on the GEM port ID information; . The method of claim 1, The preamble, Ethernet frame structure further comprises a Start of Port-ID Delimiter (SPD) (0xd5), and Cyclic Redundancy Checking (CRC8). 3. The method of claim 2, Wherein the SPD (0xd5) is 2 bytes, the GEM port ID information is 12 bits, and the CRC8 is 1 byte. The method of claim 1, The GEM port ID information indicates unicast and multicast channel information to an optical network unit (ONU) for the Ethernet frame. The method of claim 1, The data frame includes destination address information (DA), source address information (Source address: SA), packet type and length information (Type / Length), and frame transmission error detection information (Frame Check Sequence: FCS). Ethernet frame structure, characterized in that it further comprises. The method of claim 5, The destination address information (DA) is 6 bytes, the source address information (SA) is 6 bytes, the type and length information (Type / Length) of the packet is 2 bytes, the data is 46 to 1500 bytes, and the frame Ethernet frame structure, characterized in that the transmission error detection information (FCS) is composed of 4 bytes. In the Ethernet frame switching method of the Ethernet switch for the Ethernet frame transmitted from the OLT in the GPON Encapsulation Mode (GEM) mode of the gigabit passive optical subscriber network (GPON), (a) the OLT inserting GEM port ID information necessary for the switching operation of the Ethernet switch into the preamble of the Ethernet frame transmitted from the ONU and transmitting the same to the Ethernet switch; And and (b) the Ethernet switch switching the Ethernet frame according to a virtual port based on the GEM port ID information inserted into the Ethernet frame. The method of claim 7, wherein In the step (a), the OLT is, Performing interface matching with the Ethernet switch and a Gigabit Media Independent Interface (GMII) interface during initialization; Inserting the GEM port ID information generated for each channel set between the OLT and the ONU into a preamble of the Ethernet frame; And And transmitting the Ethernet frame into which the GEM port ID information is inserted, to the Ethernet switch. The method according to claim 7 or 8, In the step (b), the Ethernet switch, Receiving the Ethernet frame transmitted from the OLT, detecting the GEM port ID information included in a preamble of the Ethernet frame; Generating the virtual port based on the detected GEM port ID information; And Switching the Ethernet frame to the ONU based on the generated virtual port. The method of claim 9, The ethernet switch, And configuring, storing, and managing a table including the ONU information, the GEM port ID information, and the MAC address information for each virtual port. The method of claim 9, The virtual port generation step, The Ethernet switch further comprises the step of allocating the virtual port for each Alloc ID (Allocation Identifier) information that refers to a transmission container (T-CONT) in the ONU based on the detected GEM port ID information. Ethernet frame switching method. The method of claim 11, The ethernet switch, And configuring and storing and managing a table including the ONU information, the Alloc ID information, the GEM port ID information, a MAC address, a VLAN ID value, and a Priority value for each virtual port. Ethernet frame switching method.

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