JP4903475B2 - Cable modem, set top box - Google Patents

Description

  The present invention relates to a cable modem having a function of extracting a designated packet regardless of the destination (the contents of the MAC address), and a set-top box incorporating such a cable modem, and more particularly, if the built-in cable modem is SNMP. The present invention relates to a set top box having a function as a proxy agent.

  Conventionally, information held by a cable modem (CM) connected to a CATV network or a bidirectional set-top box (STB: Set Top Box) incorporating a CM module, as well as terminals connected to the cable modem, Monitor centrally the information of broadcast receivers (hereinafter collectively referred to as “connected devices, etc.”) built in the set-top box together with the CM module using Simple Network Management Protocol (SNMP)・ It is controlled.

  In addition, an SNMP proxy agent function is added to a cable modem or CM module (hereinafter collectively referred to as “cable modem, etc.”), and the cable modem or the like has a proxy response to the information held by the connected device. Thus, there is also known a management apparatus that can easily acquire information held by a connected device or the like by simply making an inquiry to a cable modem or the like.

In this case, specifically, a management information base (MIB: Management) possessed by a cable modem or the like.
A part of the object ID of the Information Base) is allocated for the connected device and the like, and when the cable modem or the like receives the SNMP packet targeting the information of the corresponding object ID, the cable modem or the like manages the device. Instead of the device, information is collected from the connected device, etc., and the collected information is returned instead of the connected device.

  By the way, in the case of a cable modem or the like in which a function as a normal SNMP agent is mounted, even if an SNMP packet that needs to be proxied (that is, requests information on a connected device or the like) is received, the requested information Cannot be obtained and an incorrect response will be returned.

  For this reason, when the implemented function is to be used effectively, the SNMP packet to be proxied is extracted by any method before the SNMP packet reaches the processing module that realizes the function as the SNMP agent. This needs to be processed by a processing module that realizes a function as a separately provided SNMP proxy agent.

As one method for realizing this, it is conceivable to use a packet capture (snoop) function (see, for example, Patent Document 1) provided for performing packet monitoring or the like.
JP 2002-158893 A

  However, this packet capture function is configured to monitor all packets passing through the cable modem, and it is necessary to examine the data portion of the packet in order to identify whether it is a specified packet or not. For this reason, it is necessary to temporarily store not only the address part of the packet but also the data part in the buffer.

  For this reason, a large delay occurs in all the packets, and there is a problem that the throughput is greatly reduced, and a load of the cable modem is also increased by using the packet capture function.

  In order to solve the above problems, the present invention reduces the processing load and improves throughput when a packet is extracted using a packet capture function in a cable modem or a set-top box incorporating a cable modem. The purpose is to plan.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a first port connected to a CATV network and one to a plurality of terminals that perform communication via the CATV network are connected. Relay a plurality of second ports and a received packet received via at least the first port to a second port where a terminal having the MAC address exists according to a MAC address assigned to the received packet And a bridge means for extracting a received packet addressed to the own apparatus, a packet processing means for executing a preset normal process based on the received packet addressed to the own apparatus extracted by the bridge means, and the received packet. Packet capture means for extracting a designated packet designated in advance from the received packet with reference to the information shown in the data portion of In the cable modem, the packet capture means is set to extract the designated packet from the received packets destined for the own apparatus extracted by the bridge means. Exception processing execution means for executing different exception processing, and a designated packet extracted by the packet capture means, if the designated packet is subject to exception handling, the exception handling means; otherwise, the packet Distributing means for processing by the processing means is provided.

  The invention according to claim 2 is the cable modem according to claim 1, wherein the designated packet is an SNMP packet, and the normal processing is a process for realizing a function as an SNMP agent that responds to an SNMP packet for its own device, The exception process is a process for realizing a function as an SNMP proxy agent that makes a proxy response for an SNMP packet to a terminal connected to the second port.

  The invention described in claim 3 is a set-top box, comprising: the cable modem according to claim 2; and a broadcast receiving unit that receives a broadcast transmitted via a CATV network, and the exception processing. The means is characterized in that it makes a proxy response for at least an SNMP packet to the broadcast receiving unit.

  According to the cable modem according to claim 1, since only the received packet addressed to the own apparatus which may be a designated packet is a target of processing by the packet capture means, the processing load of the packet capture means (and thus the cable modem) Can be reduced, and an unnecessary delay is not given to the received packet relayed to the second port, so that the throughput can be improved.

  According to the cable modem according to claim 2 and the set-top box according to claim 3, the function of a normal SNMP agent and the function of packet capture (snoop) implemented in the cable modem are effectively used. A function as an SNMP proxy agent can be added.

Embodiments of the present invention will be described below with reference to the drawings.
(1) Overall Configuration FIG. 1 is a block diagram showing an overall configuration of a CATV system configured using a set top box (STB) to which the present invention is applied.

As shown in FIG. 1, the CATV system includes a CATV center 1 and a set top box 3 connected to the CATV center 1 via a CATV network N1.
The CATV center 1 performs a broadcasting service with a network management unit 10 in which a management device 101, a DHCP server 103, a router 105, a cable modem termination system (CMTS) 107, and the like are connected by a hub 109. Broadcast service management unit (so-called headend) 12, which are connected to the CATV network N 1 via a mixer 14.

  Among these, the management apparatus 101 is configured by a known computer system including a control unit, a storage unit, a communication unit, and the like, and is connected to a set top box 3 (or a television described later) connected via a CATV network N1. At least a process as a so-called SNMP manager that collects related information on the receiver 5) using a simple network protocol (SNMP) is executed.

  In the present embodiment, “related information” refers to a history of selecting a channel to be auditioned via the set top box 3, a signal level in the selected channel, an SN ratio or bit of a transmission path to the set top box 3. It includes at least status information indicating quality information such as an error rate and software (firmware) version in the set top box 3. That is, these pieces of related information are management information base (MIB) objects.

  The DHCP server 103 is configured by a well-known computer system including a control unit, a storage unit, a communication unit, and the like. The set-top box 3 (a cable modem unit 30 and a later-described cable modem unit 30 and the like) are configured in accordance with DHCP (Dynamic Host Configuration Protocol). A process for assigning an IP address to the broadcast receiving unit 40) is executed.

The router 105 is a known router including a control unit, a storage unit, a communication unit, and the like, and connects the network management unit 10 to the Internet N2 so as to be capable of bidirectional communication.
Also, the cable modem termination device 107 connects the network management unit 10 via the mixer 14 so as to be capable of bidirectional communication with the CATV network N1.
(2) Configuration of Set Top Box Here, FIG. 2 is a block diagram showing the configuration of the set top box 3.

  As shown in FIG. 2, the set top box 3 is capable of two-way communication with the CATV network N1 via the cable modem unit 30 and the cable modem (CM) unit 30 connected to the CATV center 1 via the CATV network N1. A broadcast / receiver 40 connected thereto, a downstream signal from the CATV network is distributed to the cable modem 30 and the broadcast receiver 40, and a mixer / demultiplexer 50 that outputs the upstream signal from the cable modem 30 to the CATV network. It is comprised by.

  Among these, the broadcast receiving unit 40 includes a plurality of RF receiving units 41, a reception managing unit 43, a video / audio processing unit 45, and the like, and is used in a state in which a television receiver (TV) 5 is connected. It realizes the original function of.

The RF receiving unit 41 includes a receiving circuit, a tuner, a demodulating circuit, and the like, extracts a signal of a designated channel from the downlink signal supplied from the mixer / demultiplexer 50, and converts it into a video signal or an audio signal. Demodulate.

  The reception management unit 43 is configured by a known microcomputer including a control unit, a storage unit, a communication unit, and the like, and the video signal and audio signal extracted and demodulated by each RF reception unit 41 are externally transmitted. Is selected in accordance with a command from, and supplied to the video / audio processing unit 45. In addition, the above-described related information is collected and stored in the management information base (MIB), and the related information is notified or changed in response to a request from the cable modem unit 30 to the cable modem unit 30. The process of sending a response is executed.

The video / audio processing unit 45 edits the video signal and audio signal supplied via the reception management unit 43 in accordance with a command from the reception management unit 43 and supplies the edited video signal and audio signal to the television receiver 5.
On the other hand, the cable modem unit 30 includes an RF reception unit 31, an RF transmission unit 33, a CM management unit 35, a LAN interface unit 37, and a USB interface unit 39, a terminal connected to the LAN interface unit 37 and the USB interface unit 39, The apparatus or the broadcast receiving unit 40 has a function that enables bidirectional communication via the CATV network N1. Note that one or both of the LAN interface unit 37 and the USB interface unit 39 may be omitted.

  The RF receiving unit 31 is configured in the same manner as the RF receiving unit 41 of the broadcast receiving unit 40 described above, extracts a communication channel signal from the downlink signal, demodulates it into digital data, and sends it to the CM management unit 35. Supply.

The RF transmission unit 33 includes a modulation circuit, a transmission circuit, and the like. The RF transmission unit 33 modulates digital data supplied from the CM management unit 35, converts the data into a communication channel frequency, and transmits the modulated data.
The CM management unit 35 includes a bridge processing unit 130, a CM processing unit 132, a snoop processing unit 134, an SNMP proxy processing unit 136, and the like, and functions as a known cable modem.

  The bridge processing unit 130 includes a buffer circuit and a logic circuit that temporarily holds transmission / reception data, and relays communication via the cable modem unit 30 according to a MAC (Media Access Control) address, that is, OSI. (Open System Interconnection reference model) It has a function (so-called bridge function) for relaying at the data link layer level in the reference model.

  The broadcast server 40, terminals and devices connected to the interface units 37 and 39 (hereinafter collectively referred to as “connected devices etc.”), and the cable modem unit 30 are each assigned by the DHCP server 103. Apart from the IP address and unique MAC address (hereinafter referred to as “unique address”), another IP address and MAC address (hereinafter referred to as “local address”) that are valid only between them are set. These local addresses are registered in advance (stored in memory). Thereby, a virtual network independent of the network formed on the route to the CATV center 1 is formed between the cable modem unit 30 and the broadcast receiving unit 40 by the local address.

When the MAC address is a unique address, the bridge processing unit 130 performs bi-directional relay between the CATV network N1 side and the connected device side, and when the MAC address is a local address, the CATV It is set not to relay to the network N1 side. M
When the AC address is a unique address or a local address assigned to the cable modem unit 30, it is set so that it is extracted and processed in the CM management unit 35.

  In addition to the bridge processing unit 130, the CM management unit 35 includes a known microcomputer including a control unit, a storage unit, a communication unit, and the like. A CM processing unit 132, a snoop processing unit 134, and an SNMP proxy processing unit 136. Is realized by processing executed by the microcomputer.

  Among these, the CM processing unit 132 includes an MIB for the 40 to manage information on the cable modem unit 30 and information held by the connected devices and the like. As shown in FIG. 3A, in the MIB of the cable modem unit 30, the object ID having “1.” at the beginning is given to the information (object) related to the cable modem unit 30, and the connected device has An object ID starting with “2.” is assigned to the information. However, only the object ID is given to the information held by the connected device or the like, and the entity (object) is held by the connected device or the like.

  Then, the CM processing unit 132 sets the IP address assigned from the DHCP server 103 described above according to DHCP as its own IP address, or requests from the management apparatus 101 using SNMP (SNMP packet: SNMP-Get packet). , SNMP-GetNext packet, SNMP-Set packet, etc.), at least a process as a so-called SNMP agent for notifying or changing an object registered in the MIB is executed.

  Further, the snoop processing unit 134 uses the SNMP packet (that is, UDP is used and the destination port number is 161) from the packets addressed to the cable modem unit 30 (unique address, local address) extracted by the bridge processing unit 130. Are extracted and supplied to the SNMP proxy processing unit 136, and the CM processing unit 132 executes processing for other packets.

  Then, when the SNMP packet is a packet received via the CATV network N1 (a unique address is used), the SNMP proxy processing unit 136 requests the object that the SNMP packet requests for notification or change. The ID is checked, and if this object ID starts with “1.” (provided to the object held by the cable modem unit 30), it is passed to the CM processing unit 132 and is normally sent to the CM processing unit 132. The process as the SNMP agent is executed. If the object ID starts with “2.” (assigned to the object held by the connected device or the like), the SNMP packet is transferred to the connected device or the like using the local address.

On the other hand, when the SNMP packet is received from a connected device (a local address is used), only when the SNMP packet corresponds to the SNMP packet previously transferred to the connected device or the like. The packet is transferred to the CATV network N1 side using the unique address.
(3) Operation for Acquiring Information from Cable Modem Unit, Connection Device, etc. Here, when management device 101 of CATV center 1 collects information (related information, etc.) held by cable modem unit 30 or connection device, etc. The operation of will be described with reference to FIG.

First, the management apparatus 101 receives an SNMP packet (SNMP-Get packet) to request information from the cable modem unit 30 when it is time to collect information (for example, at a certain time or when an operator operates). (SNMP-GetNext packet), and waits until an SNMP packet (SNMP-Response) returned from the cable modem unit 30 is received.

  At this time, the IP address (assigned by the DHCP server 103) or the MAC address of the cable modem unit 30 managed on the CATV center 1 side, that is, the unique address is assigned to the SNMP packet to be transmitted, and the CATV network The data is transmitted to the cable modem unit 30 via N1.

  Next, when receiving the SNMP packet from the management apparatus 101, the cable modem unit 30 checks the object ID of the information (object) to be acquired, and if the object ID is “1. *”, the cable modem unit 30 holds it. The object is read from the MIB to be transmitted, and is returned using a response SNMP packet (SNMP-Response). At this time, a unique address is given to the SNMP packet to be returned.

  On the other hand, when the object ID is “2. *”, the SNMP packet is transferred to a connected device or the like (in this case, the broadcast receiving unit 40) holding the object represented by the object ID, and then broadcast received. Wait until a reply is received from the unit 40. At this time, a local address is given to the SNMP packet to be transferred.

  Next, when the broadcast receiving unit 40 receives an SNMP packet from the cable modem unit 30, it reads out an object (related information) corresponding to the designated object ID from the MIB, and reads it out as a response SNMP packet (SNMP- Response) is sent back to the cable modem unit 30. At this time, a local address is given to the SNMP packet to be returned.

  Next, when the cable modem unit 30 receives a reply of the SNMP packet from the broadcast receiving unit 40, the SNMP modem manages the SNMP packet only when it corresponds to the SNMP packet previously transmitted to the broadcast receiving unit 40. Transfer to device 101. At this time, a unique address is given to the SNMP packet to be transferred.

  Then, after the management apparatus 101 receives a reply from the cable modem unit 30 and extracts an object from this reply, a process for managing the object thus extracted (storing in a built-in storage unit, totaling related information, etc.) )I do.

That is, when the cable modem unit 30 receives a request (SNMP packet) for notifying or changing information held by the connected device or the like from the management device 101, the cable modem unit 30 acts as a proxy for the management device 101 to the connected device or the like (broadcast receiving unit 40). A notification or change is requested, and a response to the request is transmitted to the management apparatus 101 on behalf of the connected device or the like.
(4) Effect As described above, according to the set-top box 3 of the present embodiment, the cable modem unit 30 is addressed to its own device including the SNMP packet (the destination MAC address is the unique address of the cable modem unit 30). Since only received packets are processed by the snoop processing unit 134, the processing load on the snoop processing unit 134 (and thus the cable modem unit 30) can be reduced, and other packets (destination) relayed to the connected device or the like Packets whose MAC address is a unique address of a connected device or the like are not given unnecessary delay, so that the throughput of these packets to be relayed can be improved.

Further, according to the set top box 3 of the present embodiment, when the cable modem unit 30 is configured, the SNMP agent function and the snoop (packet capture) function installed in a general cable modem are effectively used. In addition, the SNMP proxy agent function can be added without changing the throughput in the cable modem unit 30 by changing the snoop target.

In addition, when an experiment for measuring the throughput using the set top box 3 was performed, in the conventional apparatus that snoops all packets, it is possible to obtain the same throughput as when the snoop function is turned off, Compared with the conventional apparatus, the throughput was improved to 3 times (12 Mbps → 35 Mbps).
(5) Modifications One embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and can take various forms as long as they belong to the technical scope of the present invention. Needless to say.

  For example, in the above-described embodiment, a configuration in which only one set-top box 3 is connected to the cable modem termination device 107 is illustrated. However, a plurality of set-top boxes 3 are connected to the cable modem termination device 107. It is good also as a structure.

  In the above embodiment, the configuration in which the related information is status information related to the set-top box 3 (or the television receiver 5) is exemplified. However, the related information may include information other than the status information. Good.

  Moreover, in the said embodiment, it is comprised so that it may be in the state by which the virtual network was formed between both by setting an effective local address only between the cable modem part 30 and the broadcast receiving part 40. The example was shown. However, as a configuration for forming a virtual network between them, a configuration other than setting a local address can be adopted. For example, by using a communication rule (for example, IPv6 when IPv4 is used) different from the communication rule used in the network formed by the route to the CATV center 1, a virtual A configuration in which a network is formed can be considered.

  Moreover, in the said embodiment, although the set top box 3 illustrated the structure made into the apparatus which integrated the cable modem part 30 and the broadcast receiving part 40, these cable modem part 30, the broadcast receiving part 40, May be constituted by a cable modem (comprising the cable modem unit 30) and a set top box (comprising the broadcast receiving unit 40), with the cable modem unit 30 being made independent of the set top box 3. .

In this case, as shown in FIG. 4, a plurality of set-top boxes 40a each including a broadcast receiving unit 40 may be connected to the cable modem 30a including the cable modem unit 30 via a relay device 7 such as a hub or a router. Good.
(6) Correspondence with the Present Invention In the embodiment described above, the bridge processing unit 130 is the bridge means, the input terminal from the RF receiving unit 31 of the bridge processing unit 130 is the first port, the interface units 37 and 39, and The output terminal to the broadcast receiving unit 40 corresponds to the second port.

  The CM processing unit 132 corresponds to a packet processing unit, the snoop processing unit 134 corresponds to a packet capture unit, and the SNMP proxy processing unit 136 corresponds to an exception processing execution unit and a distribution unit.

Block diagram showing the configuration of a CATV system Block diagram showing the configuration of the cable modem unit Explanatory diagram showing setting of MIB and sequence diagram showing outline of operation of CATV system Block diagram showing another configuration of the CATV system

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... CATV center, 3,40a ... Set top box, 5 ... Television receiver, 7 ... Relay device, 10 ... Network management part, 12 ... Broadcast service management part, 14 ... Mixer, 30 ... Cable modem part, 30a ... Cable modem, 31, 41 ... RF receiver, 33 ... RF transmitter, 35 ... CM manager, 37 ... LAN interface, 39 ... USB interface, 40 ... broadcast receiver, 43 ... receive manager, 45 ... video / Voice processing unit, 50 ... mixing / demultiplexing unit, 101 ... management device, 103 ... DHCP server, 105 ... router, 107 ... cable modem termination device, 109 ... hub, 130 ... bridge processing unit, 132 ... CM processing unit, 134: Snoop processing unit, 136: SNMP proxy processing unit, N1: CATV network, N2: Internet.

Claims (3)

A first port connected to the CATV network;
One or more second ports to which one or more terminals that perform communication via the CATV network are connected;
At least a received packet received via the first port is relayed to a second port where a terminal having the MAC address is present according to the MAC address assigned to the received packet, and received to the own device A bridge means for extracting packets;
Packet processing means for executing normal processing set in advance based on the received packet addressed to the own device extracted by the bridge means;
Referring to the information shown in the data portion of the received packet, packet capture means for extracting a designated packet designated in advance from the received packet;
In cable modem with
The packet capture means is set to extract the designated packet from the received packets destined for the own apparatus extracted by the bridge means,
Furthermore,
Exception processing execution means for executing exception processing different from the normal processing for the designated packet;
A distribution unit that causes the specified packet extracted by the packet capture unit to be processed by the exception processing unit if the specified packet is an exception processing target;
A cable modem characterized by the provision of   The designated packet is an SNMP packet, the normal process is a process that realizes a function as an SNMP agent that responds to an SNMP packet for its own device, and the exception process is a proxy for an SNMP packet for a terminal connected to the second port. The cable modem according to claim 1, wherein the cable modem is a process for realizing a function as a responding SNMP proxy agent. A cable modem according to claim 2;
A broadcast receiver for receiving a broadcast transmitted via the CATV network;
And the exception processing means makes a proxy response for at least an SNMP packet to the broadcast receiving unit.

Images