KR20000034448A - Method for packet scheduling using delay sensitive flag of cable modem - Google Patents

Abstract

PURPOSE: A method for a packet scheduling using a delay sensitive flag of a cable modem is provided to decide a transmitting order of packets according to the delay sensitive flag of each packet at the packet scheduling. CONSTITUTION: A delay sensitive flag is expressed in each packet according to a quality of a service during initializing cable modems(11-14). When packets of an upstream and a downstream channel are transmitted in the state operated the cable modems, a transmitting order is decided according to the delay sensitive flag of each packet. The transmitting order is decided according to a priority of each SID(service identifier) for packets having the same delay sensitive flag. The delay sensitive flag of each packet is set as '1' or '0' according to the quality of the service during initializing cable modems(11-14). Because packets of delay sensitive service is preferentially transmitted by deciding the transmitting order according to the delay sensitive flag expressed in each packet when the cable modem transmits packets of the upstream and the downstream channels, a request of the delay sensitive service is effectively satisfied.

Description

Method of scheduling packets using a delay sensitive flag in a cable modem

The present invention relates to a method for processing a packet of a cable modem, and more particularly to a packet scheduling method using delay sensitivity information of a cable modem for determining a transmission order of packets according to delay sensitive flag of each packet during packet scheduling. will be.

In general, the cable modem network is a network system that is attracting attention together with ISDN, multi-digital subscriber line (xDSL), etc. in the field of remote access, and is connected to the Internet and intranet to subscribers at a high speed of Mbps. It provides various services such as telecommuting, video conferencing, and web search.

The concept of cable modem networks, which have a wide user base in the United States, is to bring cable TV (CATV) networks into the data communication field. In terms of using coaxial cables, they are similar to each other. A cable modem network connects a coaxial cable to a personal computer (PC) via a cable modem, while connecting the TV to the set-top box after connecting the box. At this time, there may be one PC or multiple PCs connected to the cable modem.

Cable modems are divided into workgroup, multiuser, and personal. Workgroup cable modems are designed for small groups with 4 or 8 ports for connecting PCs, enabling them to build small LANs, and multi-user cable modems for libraries and schools. It is used in relatively large places such as factories and factories.

The cable modem is connected to the subscriber equipment (eg, PC) on one side, and the other side is connected to the cable modem terminal system through the cable network so that the subscriber can receive various services from the backbone network connected to the cable modem terminal system. To help.

That is, the cable modem appropriately processes the packets of the upstream channel input from the PC and the packets of the downstream channel input from the cable modem terminal system in the buffer and the memory, and then processes the packets accordingly. Play a role.

Meanwhile, the cable modem randomly selects data packets and transmits them to the cable modem terminal system or a PC when determining the processing order of the packets stored in the buffer and the memory.

However, if the cable modem randomly selects and transmits a data packet as described above, a delay-sensitive service, that is, a request for a service (for example, an interactive voice / video service) that significantly affects the quality of service when the packet transmission is delayed, is required. There was a problem that could not be satisfied effectively.

The present invention has been made to solve the above problems, the delay sensitive information is specified in each packet according to the quality of service during the initialization (initialization), and then in the delay (operational) state of each packet delay sensitivity information It is an object of the present invention to provide a packet scheduling method using delay sensitive information of a cable modem to more effectively satisfy the requirements of delay sensitive services by determining the transmission order accordingly.

A packet scheduling method using delay sensitive information of a cable modem according to the present invention for achieving the above object is a packet processing method of a cable modem for storing and processing the packets input from the cable modem terminal system and subscriber equipment in a buffer and a memory. In the initializing of the cable modem, a first step of specifying delay sensitivity information in each packet according to the quality of service, and delay sensitivity of each packet when transmitting uplink and downlink packets in the operation state of the cable modem. A second step of determining the transmission order according to the information, and a third step of determining the transmission order according to the priority of each SID for the packets having the same delay sensitivity information in the second step.

The first step may include adding a delay sensitive flag to a configuration file of a registration request / response message exchanged between the cable modem and the cable modem terminal system, and depending on the quality of service during the initialization of the cable modem. Preferably, the delay sensitivity flag of the packet is set to "1" or "0".

1 is a schematic diagram of a cable modem network in which the present invention is implemented;

2A is a diagram illustrating the format of a registration request message;

FIG. 2B is a diagram showing an example of the TLV coded information shown in FIG. 2A;

3A is a diagram illustrating a format of a registration response message;

FIG. 3B is a diagram showing an example of the TLV coded information shown in FIG. 3A;

<Description of the symbols for the main parts of the drawings>

11 ~ 14: Cable modem (CM) 20: Cable network

30: cable modem terminal system (CMTS) 40: backbone network

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic configuration diagram of a cable modem network in which the present invention is implemented, and a plurality of cable modems 11 to 14 (CM: Cable Modem) are connected to the cable network 20, and each cable modem 11 to 14, a personal computer (PC), which is a Customer Premises Equipment (CPE), is connected, and a cable modem terminal system (CMTS) is connected between the cable network 20 and the backbone network 40. Is connected to. Here, the subscriber receives a service such as the Internet from the backbone network 40.

The cable modems 11 to 14 (CM) store uplink packets input from the PC and downlink packets input from the cable modem terminal system 30 (CMTS) to a buffer and a memory (not shown). By properly processing in the stored state, the subscriber can receive various services from the backbone network 40 connected with the cable modem terminal system 30 (CMTS).

The cable modem terminal system 30 (CMTS) is located at the head end to provide an uplink channel and a downlink channel. The cable modem terminal system 30 transmits broadband data at a rate of 500 Kbps to 30 Mbps through a downlink channel, and each cable modem 11 to 14 CM transmits 96 Kbps to 10 Mbps over an uplink channel. Receive narrowband query data transmitted by dot method. In addition, the cable modems 11 to 14 (CM) transmit a request signal to the cable modem terminal system 30 (CMTS) and then receive an acknowledgment (ACK) signal from the cable modem terminal system 30 (CMTS). Query data requesting the necessary data must be transmitted to the cable modem terminal system 30 (CMTS).

Meanwhile, a medium access control (MAC) protocol is applied between the cable modems 11 to 14 and CM and the cable modem terminal system 30 and CMTS. The most important thing in the MAC protocol is a Service IDentifier (SID).

The SID usually provides device identification and service class management, and is necessary for upstream bandwidth allocation. The SID defines a specific mapping between the cable modems 11-14, CM and the cable modem terminal system 30, CMTS. This mapping is performed based on the class of bands and services assigned to the cable modems 11 to 14 by the cable modem terminal system 30 (CMTS). That is, the cable modem terminal system 30 (CMTS) allocates one or more SIDs to each cable modem (11-14, CM) corresponding to the service class required by the cable modems (11-14, CM). In addition, the mapping must be determined between the cable modem terminal system 30 (CMTS) and the cable modems 11-14 (CM) during the cable modem registration period.

On the other hand, the initialization process of the cable modem in order to help the understanding of the present invention.

Next, an initialization process of the cable modems 11 and CM located on the upper left side among the four cable modems 11 to 14 CM shown in FIG. 1 will be described as an example.

First, the cable modem 11 (CM) scans the downlink channel and synchronizes with the cable modem terminal system (30, CMTS). Thereafter, the cable modem 11 (CM) receives an upstream channel descriptor (UCD) message defining characteristics of an uplink channel from the cable modem terminal system 30 (CMTS) to obtain a transmission parameter. At this time, the cable modem 11, CM waits for a usable UCD message again if the upstream channel from the UCD message is not a suitable channel. If a suitable upstream channel is found from the transmission parameter, the parameter and minislot for upstream from the UCD message are found. Extract MAP message regarding timing and band allocation of selected channel. The parameter of the UCD message is defined in the form of type / length / value (TLV).

Subsequently, the cable modem 11 (CM) performs a ranging and adjustment process and then establishes an Internet Protocol (IP) connection, a current date and time, and security. The ranging is a process for obtaining a timing offset such that transmission of the cable modem 11, CM is correctly aligned with the minislot boundary.

Subsequently, the cable modem 11, CM downloads the parameter file using the Trivial File Transfer Protocol (TFTP). The TFTP is a file transfer protocol for downloading software and configuration information.

Meanwhile, after receiving the parameter file, the cable modem 11 (CM) transmits a registration request message shown in FIGS. 2A and 2B to the cable modem terminal system 30 (CMTS), and the cable modem terminal system 30 , CMTS) transmits a registration response message of the type shown in FIGS. 3A and 3B to the cable modem 11 in response to the received registration request message.

At this time, the present invention adds a delay sensitive area to the TLV encoded information area (configuration file) at the time of class of service configuration setting of the registration request message and the registration response message. For example, the delay sensitive region is added as a 1 bit flag of the form shown in Table 1 below.

Type8 Length1 Value0 or 1

Then, delay sensitivity information is specified in each packet according to the quality of service during the initialization of the cable modem 11 (CM). More specifically, packets of delay-sensitive services, that is, those that have a significant impact on the quality of service if the packet transmission is delayed (e.g., interactive voice / video service), set the delay sensitivity flag to "1" and do not delay much. Packets of a service that are not sensitive to the delay set the delay sensitivity flag to "0".

As described above, when the delay sensitivity flag of each packet is set according to the quality of service, the cable modem 11 and CM randomly selects and transmits packets as in the prior art when transmitting uplink and downlink packets in an operational state. Instead, first, the transmission order of the packets is determined according to the setting of the delay sensitivity flag of each packet, and then, for the packets with the delay sensitivity flag set to the same value, the transmission order is determined according to the priority of each SID. Determine and send packets.

More specifically, the cable modem 11 (CM) first transmits packets of the SID with the delay sensitivity flag set to "1" and transmits the packets of the SID with the delay sensitivity flag set to "0". Packets are sent later, and packets of SID having a higher priority are preferentially transmitted for packets having a delay sensitivity flag set to the same value.

As a result, the cable modems 11 and CM can satisfy the requirements of delay sensitive services more effectively than in the prior art.

In this way, the cable modem to which the present invention is applied determines the transmission order according to the delay sensitivity information specified in each packet when transmitting uplink and downlink channels, so that the packets of the delay sensitive service are transmitted first. The effect is to meet the requirements more effectively.

Claims (2)

In the packet modem packet processing method for storing and processing the packets input from the cable modem terminal system and the subscriber equipment in a buffer and memory, A first step of specifying delay sensitive information in each packet according to the quality of service during the initialization of the cable modem; A second step of determining a transmission order according to delay sensitivity information of each packet when transmitting packets of uplink and downlink channels in an operation state of the cable modem; And a third step of determining a transmission order according to the priority of each SID for packets having the same delay sensitive information in the second step. The method of claim 1, The first step may include adding a delay sensitivity flag to a configuration file of a registration request / response message exchanged between the cable modem and the cable modem terminal system. The packet scheduling method using the delay sensitivity information of the cable modem, characterized in that the step of setting the delay sensitivity flag of each packet to "1" or "0" in the initialization process of the cable modem.