JP3077659B2 - ATM cell transmission method over passive optical network, ATM communication device, optical subscriber device, and optical network device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transmitting an ATM cell through a passive optical network, an ATM communication apparatus, an optical subscriber unit, and an optical network apparatus.

[0002]

2. Description of the Related Art As is well known, ATM (Asynchronous Tra
The nsfer mode network is a fundamental technology supporting B-ISDN (wide area integrated service digital network). And this AT
As one of optical subscriber networks connecting the M network and an ONU (Optical Network Unit), there is a PON (Passive Optical Network).

Here, in an ATM network, a VP (Virtual Path) and a VC (Virtual Path) are set up between each base in the network.
Channels (virtual channels) are set, and the ATM cells are transmitted from the departure node to the destination node through these VPs and VCs. Basically, one-to-one communication, that is, unicast is assumed. . On the other hand, the PON is a network suitable for broadcasting because it transmits cells to each ONU via a common optical fiber. Therefore, in order to connect an ATM network having these different characteristics to a PON, an ATM communication device that functions as an interface is required.

[0004]

The ATM-PON
As a request for the ATM network including
Unicast for transmitting cells to one ONU, broadcast for transmitting cells from a transmitting device to all ONUs, and multiple ONs belonging to a specific group from a transmitting device
There is a need for the ability to perform multicast to transmit cells to U.

Conventionally, various techniques for broadcasting in an ATM network and techniques for performing multicast in a PON have been proposed. However, none of these techniques is functionally inadequate to satisfy the above requirements. There was no optimal device to meet the demand.

For example, Japanese Patent Laying-Open No. 8-186565 discloses a technique for performing multicast in an ATM network. In this technology, in the packet processing layer, all destination addresses to be multicast are inserted into one packet and transmitted to the ATM side. According to the descriptor of the VC to be transmitted, the packet is divided into cells until the VC to be transmitted is exhausted, and the transmission operation is repeated.

However, since this technique is to copy and transmit the cells of a broadcast packet, if this technique is applied to an ATM network including an ATM-PON, the number of cells in the ATM layer increases. There is. Further, when a PON is combined with an ATM network and the number of branches of the PON is large, there is a problem that a band allocated to each ONU becomes small.

[0008] Japanese Patent Application Laid-Open No. 7-202905 discloses that
The network is configured as a tree, and each node has separate FIFOs for user cells and broadcasts,
A technique is disclosed in which each node is connected in multiple stages to transmit a broadcast cell to all input interface points except the input interface point to which the broadcast cell is input.

However, since this technique is suitable for broadcasting but does not consider multicasting, if this technique is applied to an ATM network including an ATM-PON, ONUs other than ONUs to be multicasted are used. Cells are sent to the user, which poses a security problem.

[0010] Also, the document "Access Flexibility with Pa"
In the "ssive Double Star System", when broadcasting in the ATM-PON layer, the destination ONU in the header of the cell is set to an ID indicating broadcast, and transmission is performed without performing encryption processing.

[0011] In the case of this technique, multicast or broadcast cannot be supported, or in the case of unicast communication, packets flow to other ONUs, which poses a security problem. This is because this technique does not perform the connection with the ATM layer,
This is because the ON setting is fixed to the unicast setting or the broadcast setting.

As described above, all of the conventional techniques are not functionally sufficient to satisfy the above requirements, and
-Means for appropriately performing unicast, broadcast, and multicast in an ATM network including a PON have not been provided.

The present invention has been made in view of the above circumstances, and does not cause a security problem in an ATM network including an ATM-PON, increases traffic, and reduces the bandwidth allocated to each ONU. A that can properly perform unicast, broadcast and multicast without causing problems
It is an object of the present invention to provide a cell transmission method in a TM-PON, an ATM communication device, an optical subscriber device, and an optical network device.

[0014]

In order to solve the above-mentioned problems, according to the present invention, an ATM is connected to an optical network device in a passive optical network connected to an ATM network from an ATM network.
When transmitting M cells, an optical subscriber unit interposed between the ATM network and the passive optical network includes: a. For the optical network device to be unicast, the optical network device identification information for specifying the optical network device and the encryption key corresponding to the optical network device are stored, and for each group of the optical network device to be multicast. Stores emulated local area network identification information for specifying the group and an encryption key corresponding to the group; b. Determine whether the ATM cell is for broadcast, multicast, or unicast; c. When an ATM cell is broadcast to all the optical network devices connected to the passive optical network, identification information indicating the broadcast is added to the ATM cell as optical network device identification information, and the ATM cell is transmitted as an ATMPON frame. Sending to the passive optical network; d. When multicasting ATM cells to each optical network device belonging to a specific group connected to the passive optical network, after adding emulated local area network identification information for specifying the group to the ATM cell, Performs encryption processing using an encryption key corresponding to the group, adds identification information indicating multicasting as optical network apparatus identification information, and executes the emulated local area network.
For each of the network identification information, each of the ATM cells
Each one as an ATMPON frame to the passive optical network, e. When unicasting an ATM cell to a specific optical network device connected to the passive optical network, the ATM cell is subjected to encryption processing using an encryption key corresponding to the optical network device, and the ATM cell is encrypted. Optical network device identification information for specifying a network device is added to the ATM cell and sent to the passive optical network as an ATMPON frame. Each optical network device connected to the passive optical network includes: f. Stores a unicast encryption key used when unicast is performed on the optical network device, and stores a group to which the optical network device belongs among groups of optical network devices to be multicast. Storing an encryption key for the multicast used when the multicast is performed; g. AT arriving via the passive optical network
When the MPON frame includes the optical network device identification information corresponding to the optical network device, the ATM included in the ATMPON frame using the unicast encryption key corresponding to the optical network device.
Perform unicast reception of the cell; h. Determine whether the ATM cell is broadcast, multicast, or unicast; i. AT arriving via the passive optical network
When the MPON frame includes the identification information indicating that the broadcast is broadcast as the optical network device identification information, the ATM cell included in the ATMPON frame is broadcast-received, and j. AT arriving via the passive optical network
When the MPON frame includes the identification information indicating the multicast as the optical network device identification information,
Multicast reception of the ATM cells included in the ATMPON frame is performed using each encryption key defined for each group.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ATM communication device according to an embodiment of the present invention. This ATM communication apparatus includes a plurality of network inside interfaces 101 and a plurality of ATMPU OSUs (Optical Sc
riber unit (optical subscriber unit) 102 and an ATM switch 109 for making these connections. Here, each OSU 102 has an ONU (Optical Network) shown in FIG.
k Unit; an optical communication network device) is connected via a PON, and the OSU and the ONU constitute an ATM-PON.

The network inside interface 101 includes a protocol processing unit 104, a packet / cell processing unit 105, a device format conversion unit 106, and a device header insertion unit 107.
And a table 108.

Here, the table 108 is means for storing information necessary for switching control of the ATM switch 109. In this table 108, the port number, VPI and VCI of the ATM switch 109 for each logical connection via the network inside interface 101 are set. In the present embodiment, for each logical connection, whether it is for unicast, for multicast, or for broadcast is determined in advance as a convention in the device, and a value indicating the use of each logical connection is determined. This is set in the table 108 as ELAN information. For example, the ELAN information is set to "1" when the logical connection is for unicast, and "2" for broadcast. In the present embodiment, the OSU 10
ELAN (Emulated LA) by each ONU connected to
N; an emulated local area network), and multicast can be performed for each ONU constituting the ELAN. For the logical connection used for such a multicast, for example, “3” is set as the ELAN information. Further, there may be a case where a plurality of groups of ELANs to be multicast exist. In such a case, for each logical connection used for multicasting to each ELAN, a corresponding one of values after "3" determined for each ELAN group is set as ELAN information.

The in-device format conversion unit 106 and the in-device header insertion unit 107 convert the ATM cells from the ATM network through the communication path 103 and the packet / cell processing unit 105 into the in-device format.
9 means for supplying.

In FIG. 3, reference numeral 301 denotes a format of an ATM cell sent from the AMT network side. As shown in this figure, the ATM cell is composed of an ATM header 303 and an ATM payload 304. This ATM cell is stored in a format conversion unit 1 in the device.
06, it is converted into an in-apparatus format indicated by reference numeral 302. Then, information necessary for passing through the in-device header insertion unit 107 is inserted into the cell after the format conversion. More specifically, among the information corresponding to each logical connection in the table 108, the information corresponding to the cell is stored in the header insertion unit 10 in the device.
7 and the port number, VPI and VCI for switching among the information are the AT number of the cell.
M header 303, and the ELAN information
_ID (emulated local area network identification information) is inserted into the cell. Then, the cells that have been processed by the in-device header insertion unit 107 are supplied to the ATM switch 109.

The protocol processing unit 104 includes a communication path 103
In addition to processing of signals received from the ATM network side via the ATM network according to a predetermined protocol with an opposing device, a control protocol of an upper layer or an NMS (Netw
ork Management System)
This is a means for notifying the analysis / table setting unit 110 of the setting information from the server or the contents of the signaling protocol.

The ATM switch unit 109 transmits the cells transmitted from the above-described intra-network interface 101 to the OSU 102 corresponding to each destination. More specifically, when the ATM switch unit 109 receives a cell in the device format from the network interface 101, based on the ELAN_ID, the ATM switch unit 109 determines whether the cell is a broadcast target, a multicast target, or a unicast target. Determine if it is the target. And ATM
The switch unit 109 creates as many copies of the cell as the broadcast target as necessary and outputs the copies from all output ports. For a cell to be multicast, a specific ELA which is the destination
The value designating N is included in the cell as ELAN_ID. Therefore, the cell is output from a plurality of appropriate output ports including those corresponding to the ELAN. For cells that are subject to unicast,
Output from an appropriate plurality of output ports including the one corresponding to the destination.

The OSU 102 includes a table 110, a broadcast buffer 111, a multicast buffer 112, a unicast buffer 113, a shaper 1
14, an encryption key table 115, an encryption processing unit 116, and a PON processing unit 117.

In the table 110, in addition to the ELAN information, the port number, the VPI and the VCI similar to the table 108 of the network inside interface 101, an ONU_ID (optical network device identification information) for specifying a cell transmission rate and a destination ONU. Is stored.

The cell sent from the ATM switch 109 is determined based on the ELAN_ID as to whether it is for broadcast, for multicast, or for unicast.
1. The data is accumulated in the buffer corresponding to the cell in the multicast buffer 112 or the unicast buffer 113.

The shaper 114 reads the cells stored in each of the buffers 111 to 113 according to the table 110 and delivers the cells to the PON processing unit 117. PON processing unit 1
17 receives the cell from the shaper 114 and turns on
A U-ID is added, and sent to each ONU via the communication path 118 as an ATMPON frame. In FIG.
Reference numeral 308 indicates the format of the ATMPON frame. As shown in this figure, the ATMPON frame has ONU_ID 309.

ATMPON in PON processing section 117
The method of creating and transmitting a frame differs depending on whether a transmission target is for broadcast, multicast, or unicast. That is,
It is as follows.

A. In the case where the transmission target is a broadcast cell In this case, information indicating that the cell is for broadcast is added as ONU_ID and transmitted to the communication path 118 as an ATMPON frame. This ATMPO
The N frame includes all ONUs connected to the communication path 118.
Will be broadcast to

B. When the transmission target is a multicast cell In this case, two transmission methods can be used.

(1) First sending method In the first sending method, the multicast buffer 1
When the cell in the cell 12 is read, first, the ONU which is the destination of the cell is searched. Next, by copying the cell, the number of cells corresponding to each ONU as a destination is generated, and each ONU_ID corresponding to each ONU is added to each cell. Then, each cell is unicast to each ONU in the ATM layer.

(2) Second transmission method When this second transmission method is adopted, an encryption key is determined for each ELAN, registered in the encryption key table 115, and transmitted to each ONU constituting each ELAN. The corresponding encryption key is given in advance. In the OSU 102, when the cells in the multicast buffer 112 are read by the shaper 114, the PON processing unit 117
Then, the information corresponding to the logical connection of the cell is read from 10. Then, the PON processing unit 117 determines the destination ELAN based on the ELAN information in the read information, and determines the VPI and VC assigned to the ELAN.
I is inserted into the header of the cell. Then, the encryption processing unit 116 performs encryption processing on the cell using the encryption key corresponding to the ELAN registered in the encryption key table 115. The PON processing unit 117 outputs information indicating that the cell has been subjected to the encryption processing to the multicast as O.
It is added as NU_ID and sent to the communication path 118 as an ATMPON frame. This ATMPON frame is broadcast in the actual optical layer.

In the first and second transmission methods described above, one of them is selected depending on the security required of the network and whether the opposing ONU has a function of processing a plurality of encryption keys. .

C. When the transmission target is a unicast cell A unicast encryption key is registered in advance in the encryption key table 115 for each ONU.
The corresponding encryption key has been passed in advance. In the OSU 102, when the shaper 114 reads a cell in the unicast buffer 113, the encryption processing unit 116 sends the cell to the ONU registered in the encryption key table 115.
Is subjected to encryption processing using an encryption key corresponding to. The PON processing unit 117 adds the ONU_ID of the destination ONU to the cell after the encryption processing, and transmits the cell to the communication path 118 as an ATMPON frame. That is, in the case of unicast, cell transmission is performed in the ATM layer.

The above is the details of the method of creating and transmitting the ATMPON frame in each of the broadcast, multicast and unicast cases.

When each cell is broadcast, multicast or unicast via the communication path 118, each cell is transmitted at the transmission rate set in the table 110. Therefore, when setting the transmission rate corresponding to each logical connection in the table 110, the sum must be within the capacity limit of the communication path 118. In the present embodiment, the transmission rate is determined as follows.

First, for broadcast, a transmission rate corresponding to a band corresponding to unicast is set. For example, when performing a 1 Mbps broadcast service, even if the target ONU is eight,
What is necessary is just to set the transmission rate of 1 Mbps.

For unicast, a transmission rate corresponding to each required bandwidth is set.

In the case of multicast, the first
Alternatively, the method of setting the transmission rate differs depending on which of the second transmission methods the cell is transmitted. That is, when the first transmission method is adopted, a transmission rate corresponding to the capacity corresponding to the number of ONUs to be multicast is set, and when the second transmission method is employed, a broadcast rate is set. ONU1 as well
Set the transmission rate corresponding to the capacity of the units.

Next, the analysis / table setting section 110 will be described. The protocol processing unit 104 of the above-described network inside interface 101 notifies the analysis / table setting unit 110 of the control protocol of the upper layer, the setting information from the NMS (Network Management System), or the content of the signaling protocol. . The analysis / table setting unit 110 determines whether or not the received condition can be accepted by the ATM communication device and the ATMPON. If it is determined that the information can be accepted, the analysis / table setting unit 110 sets and stores the table held therein and the table 108 of the network inside interface 101 and O
The SU table 110 is set. Each table 108
The contents set in and 110 are as described above.

The determination as to whether or not the reception is possible may be made by another function of the ATM communication device such as CAC (Connection Admission Control), or an external device. May be performed by a server or the like.

Next, the configuration and operation of each ONU will be described with reference to FIG. As shown in FIG.
Has a table group 202, a PON processing unit 201, a synchronization processing unit 213, and an AND gate 214.

First, the table group 202 includes a unicast table 203 and a broadcast ONU_ID.
It comprises a register 204 and a multicast table 205.

Here, the unicast table 203
Is composed of an ONU_ID register 206 and an encryption key register 207. The ONU_ID of the ONU is stored in the ONU_ID register 206 in advance. The encryption key register 207 stores the above-mentioned unicast encryption key assigned to the ONU in advance.

In the broadcast ONU_ID register 204, the above-mentioned "information indicating broadcast" to be added to the broadcast cell on the OSU side is stored in advance.

The multicast table 205
Is composed of an ONU_ID register 208 and an encryption key table including encryption key registers 209-1 to 209-n. In the ONU_ID register 208, the above-mentioned "information indicating multicasting" which is added to a cell for multicasting when multicasting is performed by the second transmission method on the OSU side is stored in advance. Encryption key registers 209-1 to 209
In -n, an encryption key used when multicasting is performed by the second transmission method on the OSU side is stored in advance. That is, as described above, the second
In the transmission method of (1), the cell is encrypted using an encryption key determined for each ELAN as a destination.
In the NU, a multicast encryption key corresponding to each ELAN is set to an encryption key register 209-1 or 209-2 so that multicast reception can be performed regardless of which ELAN belongs.
09-n. When the OSU performs multicasting by the first transmission method, the ONU_ID register 208 and the encryption key registers 209-1 to 209-n are not used, and the ONU_ID register 206 for unicast is used.

Next, the PON processing section 201 has an optical layer processing section 210, an ONU_ID filter 211, and an encryption processing section 212.

The ATMON frame from the OSU is processed by the optical layer processing unit 210 and then transmitted to the ONU.
The data is sent to the encryption processing unit 212 via the _ID filter 211. When passing this ATMPON frame, ONU_
The ID filter 211 includes ONU_ in the table group 202.
Each ONU in ID registers 204, 208 and 206
_ID is compared with the ONU_ID in the frame to determine whether the frame is broadcast, multicast, or unicast.

Here, if the frame is broadcast, the ATMPON frame that has passed through the ONU_ID filter 211 passes through the encryption processing unit 212 without any processing, and the synchronization processing unit 213
Sent to

When the frame is unicast, the encryption key stored in the unicast encryption key register 207 is sent to the encryption processing unit 212. Then, using the encryption key, the ONU_ID filter 21
1 is restored, and the processed frame is sent to the synchronization processing unit 213.
Here, when the ATMPON frame is encrypted with the encryption key corresponding to the ONU, the encryption processing unit 212
Is normally performed, and is normally received by the synchronization processing unit 213. On the other hand, when the ATMPON frame is encrypted with an encryption key other than the encryption key corresponding to the ONU, the restoration processing of the encryption processing unit 212 is not normally performed, and the synchronization processing unit 213 loses synchronization.
Therefore, the ATMPON frame is discarded.

If the frame has been multicast by the second transmission method, the encryption keys stored in the multicast encryption key registers 209-1 to 209-n are sequentially transmitted to the encryption processing unit 212. Can be Then, in the encryption processing unit 212, the ONU_ID filter 2
Restoration processing using each of these encryption keys is sequentially performed on the ATMPON frame that has passed through 11, and the restored frame is sent to the synchronization processing unit 213. Here, if the encryption key supplied to the encryption processing unit 212 does not match the encryption key used for encrypting the ATMPON frame, the synchronization is lost even if the restored frame is sent to the synchronization processing unit 213. Wake up and the frame is discarded. However, the encryption key used for encrypting the ATMPON frame, that is, the encryption key corresponding to the ELAN that is the destination of the ATMPON frame, is transmitted to the encryption processing unit 212 from any of the encryption key registers 209-1 to 209-n. Then, at that time, the restoration process of the ATMPON frame using the encryption key is performed normally, and the synchronization processing unit 213 accepts the restored frame without any loss of synchronization.

When a frame is multicast by the first transmission method, the ONU_ID of one ONU to be multicast is included in the frame. In this case, the same processing as in the case of the above-described unicast frame is performed.

[0051]

As described above, according to the present invention, it is possible to perform broadcast, multicast and unicast via an ATM-PON so as not to impair both security and effective use of bandwidth. There is.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention including an OSU.
FIG. 2 is a block diagram illustrating a configuration of a TM communication device.

FIG. 2 is a block diagram showing a configuration of an ONU according to an embodiment of the present invention.

FIG. 3 shows an ATM handled by the ATM communication device.
It is a figure which shows the structure of the cell, the cell of the format in apparatus, and an ATMPON frame.

[Explanation of symbols]

 102 OSU 110 Table 115 Encryption key table 202 Table group 209-1 to 209-n Encryption key register 207 Encryption key register 201 PON processing unit

Continuation of the front page (56) References JP-A-9-205420 (JP, A) JP-A-4-213242 (JP, A) JP-A-61-114633 (JP, A) JP-A-4-120839 (JP, A) JP-A-9-191309 (JP, A) JP-A-58-143652 (JP, A) JP-A-6-152588 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H04L 12/28 H04B 10/20 H04L 9/06-9/14 H04L 12/44

Claims (3)

(57) [Claims] An ATM network side connects an ATM network device to an optical network device in a passive optical network connected to the ATM network.
A method for transmitting a cell, comprising: an optical subscriber unit interposed between the ATM network and the passive optical network, comprising: a. For the optical network device to be unicast, the optical network device identification information for specifying the optical network device and the encryption key corresponding to the optical network device are stored, and for each group of the optical network device to be multicast. Stores emulated local area network identification information for specifying the group and an encryption key corresponding to the group; b. Determine whether the ATM cell is for broadcast, multicast, or unicast; c. When an ATM cell is broadcast to all the optical network devices connected to the passive optical network, identification information indicating the broadcast is added to the ATM cell as optical network device identification information, and the ATM cell is transmitted as an ATMPON frame. Sending to the passive optical network; d. When multicasting ATM cells to each optical network device belonging to a specific group connected to the passive optical network, after adding emulated local area network identification information for specifying the group to the ATM cell, Performs encryption processing using an encryption key corresponding to the group, adds identification information indicating multicasting as optical network apparatus identification information, and executes the emulated local area network.
For each of the network identification information, each of the ATM cells
Each one as an ATMPON frame to the passive optical network, e. When unicasting an ATM cell to a specific optical network device connected to the passive optical network, the ATM cell is subjected to encryption processing using an encryption key corresponding to the optical network device, and Optical network device identification information for specifying a network device is added to the ATM cell, and the ATM cell is transmitted as an ATMPON frame to the passive optical network; and each of the optical network devices connected to the passive optical network includes: f. Stores a unicast encryption key used when unicast is performed on the optical network device, and stores a group to which the optical network device belongs among groups of optical network devices to be multicast. Storing an encryption key for the multicast used when the multicast is performed; g. AT arriving via the passive optical network
When the MPON frame includes the optical network device identification information corresponding to the optical network device, the ATM included in the ATMPON frame using the unicast encryption key corresponding to the optical network device.
Perform unicast reception of the cell; h. Determine whether the ATM cell is broadcast, multicast, or unicast; i. AT arriving via the passive optical network
When the MPON frame includes the identification information indicating that the broadcast is broadcast as the optical network device identification information, the ATM cell included in the ATMPON frame is broadcast-received, and j. AT arriving via the passive optical network
When the MPON frame includes the identification information indicating the multicast as the optical network device identification information,
A method for transmitting ATM cells via a passive optical network, wherein multicast transmission of ATM cells included in the ATMPON frame is performed using each encryption key defined for each group. 2. An optical subscriber unit for transmitting an ATM cell from an ATM network side to an optical network unit in a passive optical network connected to an ATM network, comprising: a. For the optical network device to be unicast, the optical network device identification information for specifying the optical network device and the encryption key corresponding to the optical network device are stored, and for each group of the optical network device to be multicast. Stores emulated local area network identification information for specifying the group and an encryption key corresponding to the group; b. Determine whether the ATM cell is for broadcast, multicast, or unicast; c. When an ATM cell is broadcast to all the optical network devices connected to the passive optical network, identification information indicating the broadcast is added to the ATM cell as optical network device identification information, and the ATM cell is transmitted as an ATMPON frame. Sending to the passive optical network; d. When multicasting ATM cells to each optical network device belonging to a specific group connected to the passive optical network, after adding emulated local area network identification information for specifying the group to the ATM cell, Performs encryption processing using an encryption key corresponding to the group, adds identification information indicating multicasting as optical network apparatus identification information, and executes the emulated local area network.
For each of the network identification information, each of the ATM cells
Each one as an ATMPON frame to the passive optical network, e. When unicasting an ATM cell to a specific optical network device connected to the passive optical network, the ATM cell is subjected to encryption processing using an encryption key corresponding to the optical network device, and the ATM cell is encrypted. An optical subscriber unit, wherein optical network unit identification information for specifying a network unit is added to the ATM cell, and the ATM cell is transmitted to the passive optical network as an ATMPON frame. 3. An optical network device for receiving an ATM cell from the ATM network via a passive optical network connected to the ATM network, f. Stores a unicast encryption key used when unicast is performed on the optical network device, and stores a group to which the optical network device belongs among groups of optical network devices to be multicast. Storing an encryption key for the multicast used when the multicast is performed; g. AT arriving via the passive optical network
When the MPON frame includes the optical network device identification information corresponding to the optical network device, the ATM included in the ATMPON frame using the unicast encryption key corresponding to the optical network device.
Perform unicast reception of the cell; h. Determine whether the ATM cell is broadcast, multicast, or unicast; i. AT arriving via the passive optical network
When the MPON frame includes the identification information indicating that the broadcast is broadcast as the optical network device identification information, the ATM cell included in the ATMPON frame is broadcast-received, and j. AT arriving via the passive optical network
When the MPON frame includes the identification information indicating the multicast as the optical network device identification information,
An optical network device for performing multicast reception of ATM cells included in the ATMPON frame using each encryption key defined for each group.