KR20080068408A - Point-to-multipoint communication method and apparatus in epon - Google Patents

Abstract

A point-to-multipoint communication method in an Ethernet-based PON(Passive Optical Network) and a device thereof are provided to solve a problem that communication is not available among ONUs(Optical Network Units) when traffic is abandoned, and to enable an OLT(Optical Line Terminal) to disguise MAC(Medium Access Control) addresses of the ONUs to send an ARP(Address Resolution Protocol) response on behalf of the ONUs, thereby preventing a potential risk of hacking. An OLT(30) comprises as follows. A proxy ARP plus block(302) searches ARP tables of all interfaces including an interface which transmits an ARP request, and transmits an ARP response to the corresponding destination even when transmitting/receiving interfaces are the same. An L2/L3 switch block(300) individually relays communication between the proxy ARP plus block and an L2/L3 switch block and communication between ONUs(304,306).

Description

POINT-TO-MULTIPOINT COMMUNICATION METHOD AND APPARATUS IN EPON}

1 is a block diagram showing an example of a conventional passive optical network (Passive Optical Network)

FIG. 2 is a schematic block diagram of a router when a typical proxy ARP function is enabled.

3 is a block diagram illustrating communication between an optical network unit (ONU) using a proxy ARP Plus function and an L2 (Link Layer) / L3 (Network Layer) switch function according to an embodiment of the present invention. Diagram

4 is a flowchart illustrating communication between an optical network unit (ONU) using a proxy ALP plus function and an L2 / L3 switch function according to an embodiment of the present invention.

The present invention relates to an optical line terminal device (Optical Line Terminal: hereinafter referred to as "OLT") and an optical network unit (hereinafter referred to as "EPON") in an Ethernet passive optical network (hereinafter referred to as "EPON"). The present invention relates to a communication technology having a point-to-multipoint structure between ONUs, and more particularly, to enable communication between a plurality of ONUs belonging to the same OLT link.

1 is a block diagram showing an example of a conventional PON network.

Typically, a PON includes one OLT and a number of ONUs. In the example of FIG. 1, three ONUs 102A, 102B, 102C and user terminals 104A, 104B, 104C in one OLT 10 are passive optical. An example of connecting through a distribution system (hereinafter referred to as "ODN") is shown. Referring to FIG. 1, the OLT 10 is located at the root of a tree structure and plays a central role in providing information to each subscriber of an access network. An ODN 16 is connected to the OLT 10. The ODN 16 has a tree topology structure and transmits downstream data frames transmitted from the OLT 10 to the ONUs 102A, 102B, and 102C. And multiplexes upstream data frames from the ONUs 102A, 102B, 102C and transmits them to the OLT 10. On the other hand, the ONUs 102A, 102B, 102C receive downlink data frames and provide them to the user terminals 104A, 104B, 104C and upstream the data output from the user terminals 104A, 104B, 104C. The data is transmitted to the OLT 10 via the ODN 16 as a frame. In this case, the user terminals 104A, 104B, and 104C connected to the respective ONUs 102A, 102B, and 102C, respectively, refer to various types of subscriber network terminators that can be used in the EPON.

As shown in FIG. 1, the characteristic of the EPON network is that the downlink traffic transmitted by the OLT 10 is received by a plurality of ONUs 102A, 102B, and 102C, and the uplink traffic is a plurality of ONUs 102A, 102B, and 102C. In order to prevent collisions because they share the same medium, a TDM (Time Division Multiplexing) sharing scheme is required.

However, in the EPON network, since the OLT 10 switches according to the Ethernet protocol, when the received traffic is transmitted on the same link, the OLT 10 discards the traffic. Therefore, in order to enable communication between the ONUs 102A, 102B, and 102C, the traffic received by the OLT 10 must be transmitted on the same link. As a result, communication between the OLT 10 and the ONUs 102A, 102B, and 102C is possible in the EPON network, but communication between the ONUs 102A, 102B, and 102C is not possible due to the characteristics of the medium.

Accordingly, the present invention is to provide a method for resolving communication between ONUs without the traffic is discarded when the traffic received from the OLT in the EPON network is transmitted on the same link.

According to an aspect of the present invention for achieving this, in the point-to-multi-point communication method in an Ethernet-based passive optical network, communication at the optical line terminal (OLT) end If you send an address resolution protocol request for the ONU to receive the communication from the ONU (Optical Network Unit) requesting the request to the ONU to receive the communication, the response is received from the ONU to receive the communication. And a second process of collecting an AL table of an ONU to be requested for communication, setting up an L3 forward table between the ONU to be requested for communication and the ONU to be requested for communication, and communicating the ALP response. And a third process of connecting the communication between the ONU requesting the communication and the ONU receiving the communication by transmitting to the requested ONU.

According to another aspect of the present invention, in the point-to-multi-point communication device in an Ethernet-based passive optical network, the optical line terminal (OLT) end is the address resolution Protocol) Proxy ARP Plus which searches the ALP tables of all interfaces including the interface that sent the request and sends the ARP response to the corresponding destination even if the sending and receiving interfaces are the same. And a L2 / L3 switch block for mediating communication between the proxy ALP plus block and the L2 / L3 switch block and the communication between the ONU (Optical Network Unit).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific details such as specific components are shown, which are provided to help a more general understanding of the present invention, and the specific details may be changed or changed within the scope of the present invention. It is self-evident to those of ordinary knowledge in Esau.

As mentioned in the related art, in the case of the inter-ONU communication, the traffic received in the OLT has to be transmitted on the same link. Therefore, the EPON network proposed by the present invention to solve the problems mentioned in the prior art is a new that enables communication between ONU using the "Proxy ARP Plus" function and L2 / L3 switch function to be described later Suggest a configuration. In the present invention, a process of solving the communication problem between ONUs using the proxy ALP Plus method will be described.

The proxy ALP plus function proposed by the present invention will be described below as a function of improving the problem of the proxy ALP before describing the function of the proxy ALP plus. Proxy ARP's function is to map the IP address, which is the logical address of the L3 switch, to the MAC address, which is the physical address of the L2 switch. An IP address is a unique value representing a terminal connected to the Internet. Even though it is on another subnet, the IP address is valid, but the MAC address is valid only within one IP subnet. If Host A wants to communicate with Host B on a different subnet, it needs to know Host B's MAC address in order to communicate with the owner of the IP address, namely Host A and Host B. Function to enable communication. In FIG. 2, an example in which communication between hosts through a router is performed using the function of the proxy ALP will be described.

2 is a schematic block diagram showing a router 20 when a typical proxy ALP function is activated. As shown in FIG. 2, Host A 22 and Host B 24 are located on different subnet interfaces, and Host A 22 has a subnet length of / 16. That is, the subnet mask is 16. In the general ALP operation, in this case, the host A 22 cannot send an ARP request packet to the host B 24. In normal ALP operation, ALP packets cannot communicate to other subnet interfaces. In this case, if proxy ALP is set, proxy ALP can see the sender information or ALP request packet of the received ALP message, update the ALP table, and check the ALP table of the adjacent subnet interface to check Host B ( If ALP of 24) exists, the router gateway of the subnet interface to which the host A 22 belongs to relays communication in response to ALP.

However, the existing proxy ALP refers to only the ALP table of the other interface except the interface requesting the ALP, and only responds to the gateway MAC address if the ALP exists in the ALP table of the other interface. ONU communication problem could not be solved.

The method of extending the problem of the proxy ALP according to the characteristics of the present invention is the proxy ALP Plus. Proxy ALP Plus scans the ALP tables of all interfaces including the received interface and sends MAC addresses in an ALP response when MAC addresses exist in the ALP tables. Communication between ONUs is possible. In FIG. 3, the proxy ALP Plus function will be described as an example.

3 is a schematic block diagram of communication between ONUs using the proxy ALP Plus function and the L2 / L3 switch function according to an embodiment of the present invention. As shown in FIG. 3, the OLT unit 30 includes an L2 / L3 switch block 300 and a proxy ALP plus block 302 that are in charge of the L2 / L3 switching function. In the L2 / L3 switch block 300, communication between the same subnet interface is handled by L2 switching using a MAC address, which is the physical address of the L2 switch, and communication between non-identical subnet interfaces is performed using an IP address, which is a logical address of the L3 switch. L3 switching is in charge. The L2 switch is used for communication between the proxy ALP plus block 302 and the L2 / L3 switch block 300 in the OLT unit 30, and the L3 switch is used for communication between the OLT unit 30 and the ONU unit 30. Used. The L2 / L3 switch block 300, which is in charge of the L2 / L3 switching function, searches the ALP table of all interfaces including the interface received by the function of the proxy ALP Plus block 302, and the MAC address is entered in the ALP table. If present, the MAC address is sent in an ARP response. Therefore, even when the transmitting and receiving interfaces are the same, communication between the ONUs 304 and 306 becomes possible. In FIG. 4, an operation method for communication between ONUs using the proxy ALP Plus function proposed by the present invention will be described.

4 is a flowchart illustrating communication between ONUs using a proxy ALP plus function and an L2 / L3 switch function according to an embodiment of the present invention. 4, when ONU A 304 and ONU B 306 are located on different subnets and communication between ONU A 304 and ONU B 306 is required in step 400, ONU A 304 is determined. An ALP request for ONU B 306 is sent to OLT 30. The ALP packet transmitted from the ONU A 304 by the EPON medium characteristic is transferred to the proxy ALP plus block 302 in the OLT 30 part. If the proxy ALP plus block 302 relays in step 402 and transmits an ARP request received from the ONU A 304 to the ONU B 306, in step 404, the ONU B having received an ALP request from the OLT 30 ( 306 sends an ALP response to the OLT 30. In step 406, the proxy ALP plus block 302 collects an ALP table for the MAC address and the IP address of the ONU B 306 in the ALP response packet received from the ONU B 306. The AL table collected from the ONU B 306 is used for the L2 / L3 switch block 300 to the L2 / L3 for the MAC address and IP address of the ONU B 306 in the ALP response packet received from the ONU B 306. Inform switching information. The L2 / L3 switch block 300 sets the L3 forward table between the ONU A 304 and the ONU B 306 based on the information provided by the proxy ALP plus block 302. After setting the L3 forward table, the proxy ALP plus block 302 sends the ONU A 304 the MAC address for the ONU B 306 as the gateway MAC address of the OLT 30. In step 408, the ONU A 304 receiving the ALP response to the ONU B 306 from the OLT 30 sets the MAC address of the OLT 30 to the MAC address of the OLT 30 in step 410. . In operation 412, the L2 / L3 switch block 300 transmits the traffic received from the ONU A 304 to the ONU B 306 to solve the inter-ONU communication problem.

In addition, since the OLT 30 impersonates the MAC address of the ONU B 306 in step 406 and sends an ALP response to the ONU A 304 instead, the ONU A 304 sends the MAC address of the ONU B 306. Since it is unknown, the ONU can also expose the MAC address, which can also be a threat of hacking.

As described above, the configuration and operation for solving the communication problem between ONU in the EPON system network according to an embodiment of the present invention can be made, while in the above description of the present invention has been described a specific embodiment various modifications It may be practiced without departing from the scope of the invention. Therefore, the scope of the present invention should not be defined by the described embodiments, but by the claims and equivalents of the claims.

As described above, according to the present invention, when the traffic received from the OLT in the EPON network is transmitted on the same link, the traffic is discarded and the communication between the ONUs is not possible, and the OLT impersonates the MAC address of the ONU. By sending an ARP response instead, it is possible to prevent the potential threat of hacking caused by the ONU's MAC address exposure.

Claims (7)

In the point-to-multipoint communication method in an Ethernet-based passive optical network, If an OLT (Address Resolution Protocol) request for the ONU to be received from the optical network unit (ONU) requesting communication at the OLT (Optical Line Terminal) end is transmitted to the ONU to be requested for the communication Receiving a response from an ONU to receive a request; A second process of collecting an AL table of the ONU to receive the communication request and setting an L3 forward table between the ONU requesting the communication and the ONU requesting the communication; And a third process of transmitting the ALP response to the ONU requesting the communication to connect communication between the ONU requesting the communication and the ONU requesting the communication. The method of claim 1, wherein the first process is  Receiving the ALP request sent by the ONU requesting the communication in the Proxy ARP Plus block in the OLT terminal and transmitting the ALP request to the ONU to receive the communication again; And receiving an ALP response from an ONU that will receive the ALP request upon receiving the ALP request. The method of claim 1, wherein the second process L2 / L3 switching information for the MAC address and IP address of the ONU for which the ALP table for the ONU to be requested for the communication collected in the proxy ALP Plus block is requested to the L2 / L3 switch block in the OLT stage Telling you, And setting, by the L2 / L3 switch block, an L3 forward table between the ONU requesting the communication and the ONU requesting the communication based on the L2 / L3 switching information informed by the proxy ALP plus block. Point-to-multipoint communication method in EPON network. The method of claim 1, wherein the third process is Intermediary at the L2 / L3 switch block in the OLT, and instead receiving traffic from the ONU that requested the communication in the L2 / L3 switch block to the ONU to receive the communication;  And transmitting traffic instead from the ONU requesting the communication in the L2 / L3 switch block to the ONU to receive the communication. In the point-to-multipoint communication device in an Ethernet-based passive optical network, the optical line terminal (OLT) end is Proxy Resolution AP Searches the AP tables of all interfaces, including the interface that sent the Request Resolution Protocol, and sends an AP response to the destination even if the sending and receiving interfaces are the same. (Proxy ARP Plus) block, And a L2 / L3 switch block for mediating communication between the proxy ALP plus block and the L2 / L3 switch block and the communication between the ONU (Optical Network Unit). The method of claim 5, wherein the proxy ALP plus block In the EPON network characterized in that the threat of the exposure of the MAC address of the ONU to be requested to be transmitted by sending the ARP response to the ONU requesting the communication by disguising the MAC address of the ONU to be requested to receive the communication. Multipoint communication device. The method of claim 5, wherein the L2 / L3 switch block An L2 switch for mediating communication between the proxy ALP plus and the L2 / L3 switch in the OLT terminal located on the same interface using a MAC address; Point-to-point multi-point communication device in the EPON network comprising an L3 switch for relaying the communication between the OLT terminal and the ONU terminal located on the other interface using an IP address.

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