JP2011082699A - Handover control method, mag, and control program of mag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use a buffer amount of a MAG (Mobile Access Gateway), to prevent deterioration in communication quality of a mobile terminal which utilizes a real time application with low allowable values to jitter and delay, to prevent a transfer of a useless traffic to a radio access network, and to prevent deterioration in communication quality of other terminals connected to the radio access network. <P>SOLUTION: This handover control method includes: a step S2 of notifying information showing the application which is utilized by the mobile terminal from a PMAG (Previous Mobile Access Gateway) to an NMAG (Next Mobile Access Gateway); a step S5 of specifying allowable delay time of the application on the basis of time required for handover guessed beforehand and the information showing the application in the NMAG; a step S10 of discarding packets in delays which exceed the allowable delay time in a received order after starting buffering; and a step S11 of transferring the buffered packets to the mobile terminal upon connection of the mobile terminal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is performed between a movement source MAG and a movement destination MAG in a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. The present invention relates to a technique for controlling handover of a mobile terminal.

  In recent years, fixed-line and mobile telecommunications carriers that provide public line switching services have been working with Internet services to integrate fixed- and mobile networks based on the NGN (Next Generation Network) architecture, which is being standardized as the next-generation network. The transition to an IP-based network that is easy to integrate is underway. Non-Patent Document 3 describes IMS (IP Multimedia Subsystem), which is the core technology of NGN. In IMS, in order to implement QoS and policy control, PCRF (Policy and Charging Rules Function) which is a resource control server is used.

  At present, in 3GPP, 3GPP2, and ITU-T, as described in Non-Patent Document 4, from P-CSCF (Proxy Call Session Control Function) corresponding to AF (Application Function) such as SIP (Session Initiation Protocol) server. A policy control procedure for making a network resource request to the PCRF is defined. Furthermore, a procedure for opening / closing a port and setting a policy for controlling media traffic from a user is defined from the PCRF to an AGW (Access Gateway) which is a transport edge router.

  FIG. 2 is a diagram showing a procedure of PFMIP Predictive type fast handover. The mobile terminal (MN) 40 notifies the MAG (PMAG) 20 of the next radio access network to be connected before performing the handover (procedure 1). The source MAG (PMAG) 20 establishes a bidirectional tunnel with the MAG (NMAG) 30 to which the mobile terminal 40 is connected next (procedure 2). The PMAG 20 transfers downlink traffic addressed to the mobile terminal to the NMAG 30 in accordance with the withdrawal of the mobile terminal (procedure 3). When the mobile terminal completes connection to the NMAG 30 (procedure 4), the LMA 10 switches the bidirectional tunnel established with the PMAG 20 to the NMAG 30 (procedure 5).

  In this way, in the PFMIP Predictive fast handover procedure, while the mobile terminal switches the radio access, the packet addressed to the mobile terminal performing the handover is buffered in the NMAG to prevent packet loss. Yes.

S. Gundavelli, "Proxy Mobile IPv6", IETF RFC 5213, August 2008 H.Yokota, “Fast Handovers for Proxy Mobile IPv6”, IETF internet-draft, June 2009 3GPP TS 23.203 V8.4.0 "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Policy and charging control architecture (Release 8)" IETF RFC3261 “Session Initiation Protocol”

  However, in the above-described conventional technology, while the mobile terminal switches the radio access (when performing the handover), the focus is only on preventing packet loss from occurring. In other words, in the Predictive method using PFMIP, packets destined for the mobile terminal are buffered at the destination MAG to prevent packet loss during handover. However, since the buffer amount in MAG is finite, if an attempt is made to prepare a buffer amount so as not to cause packet loss for all traffic, an enormous buffer amount is required.

  In real-time applications, there are acceptable values for delay and jitter, and traffic exceeding the allowable values degrades the quality of the application. That is, in a real-time application, quality cannot be ensured only by preventing packet loss. Therefore, it is necessary to consider the delay caused by the handover and the increase in jitter. In addition, for example, in a handover of a radio access network using a shared medium such as a wireless LAN, communication delay of other terminals may be increased by performing buffering.

  The present invention has been made in view of such circumstances, effective use of the MAG buffer amount, prevention of deterioration in communication quality of a mobile terminal using a real-time application with low tolerance for jitter and delay, Provided are a handover control method, a MAG, and a MAG control program capable of preventing unnecessary traffic from being transferred to the radio access network and preventing deterioration in communication quality of other terminals connected to the radio access network. The purpose is to do.

  (1) In order to achieve the above object, the present invention takes the following measures. That is, the handover control method according to the present invention includes a source MAG and a destination MAG in a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. Is a handover control method for controlling a handover of a mobile terminal performed between the mobile terminal and the source MAG, when receiving a notification from the mobile terminal that a handover is to be performed, A step of notifying execution of handover of the mobile terminal; a step of notifying the destination MAG of information indicating an application used by the mobile terminal; and a bidirectional tunnel between the destination MAG And entering and exiting the radio access network at the destination MAG Based on the traffic to be performed, estimating the time required for the mobile terminal to perform the handover, and based on the estimated time required for the handover and the information indicating the notified application, an allowable delay time allowed by the application is determined. A step of identifying, a step of comparing the estimated time required for the handover with the allowable delay time, and, as a result of the comparison, if the allowable delay time is longer than the estimated time required for the handover, A step of buffering packets received from the MAG; a step of discarding packets that have passed the allowable delay time since the start of the buffering; and when the mobile terminal is connected The buffered packet from the mobile terminal Characterized in that it comprises the steps of transferring at least.

  In this way, the allowable delay time is calculated according to the application of the mobile terminal, and after the buffering is started, the packets that have passed the allowable delay time are discarded in the order received, so the buffer held by the destination MAG It is possible to effectively use the amount, and it is possible to prevent deterioration in communication quality of a mobile terminal using a real-time application with a low tolerance for delay and jitter. Further, when the destination MAG is a shared medium such as a wireless LAN, buffering in the destination MAG at the time of handover and discarding unnecessary packets can be prevented from flowing unnecessary traffic into the radio access network. Therefore, it is possible to prevent deterioration in communication quality of other terminals connected to the radio access network.

  (2) Further, according to the handover control method of the present invention, when the allowable delay time is shorter than the estimated time required for the handover as a result of the comparison, the destination MAG receives the packet received from the source MAG. The buffering is stopped.

  As described above, when the allowable delay time is shorter than the estimated time required for the handover as a result of the comparison, the destination MAG stops buffering of the packet received from the source MAG, so the time required for the handover and the allowable time It is possible to switch the execution of buffering according to the delay time.

  (3) The MAG of the present invention is a MAG that is applied to a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. When receiving a notification from the subordinate mobile terminal that the handover is to be performed, the handover destination MAG is notified of the handover of the mobile terminal and the mobile terminal is informed of the handover MAG. Is notified of information indicating an application being used by the user, and a bidirectional tunnel is established with the destination MAG.

  In this way, information indicating the application used by the mobile terminal is notified to the destination MAG, so the destination MAG calculates an allowable delay time according to the application of the mobile terminal, and performs buffering. Packets whose allowable delay time has elapsed since the start can be discarded in the order received. This makes it possible to effectively use the amount of buffer held by the destination MAG, and to prevent deterioration in communication quality of mobile terminals that use real-time applications with low tolerances for delay and jitter. It becomes. Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

  (4) The MAG of the present invention is a MAG applied to a radio access network configured by a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. When other MAGs in communication with the mobile terminal are notified of the handover of the mobile terminal and information indicating the application used by the mobile terminal, based on the traffic input to and output from the radio access network The mobile terminal estimates the time required for handover, specifies the allowable delay time allowed by the application based on the estimated time required for handover and information indicating the notified application, and the estimated handover And the allowable delay time are compared. When the allowable delay time is longer than the time required for the handover performed, buffering of the packet received from the source MAG is executed, and after starting the buffering, the packet that has passed the allowable delay time is The received packets are discarded in the order received, and when the mobile terminal is connected, the buffered packet is transferred to the mobile terminal.

  In this way, the allowable delay time is calculated according to the application of the mobile terminal, and after the buffering is started, the packets that have passed the allowable delay time are discarded in the order received, so the buffer held by the destination MAG It is possible to effectively use the amount, and it is possible to prevent deterioration in communication quality of a mobile terminal that uses a real-time application with a low tolerance for delay. Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

  (5) Further, when the allowable delay time is shorter than the estimated time required for the handover as a result of the comparison, the MAG of the present invention stops the buffering of the packet received from the source MAG. Features.

  As described above, when the allowable delay time is shorter than the estimated time required for the handover as a result of the comparison, the destination MAG stops buffering of the packet received from the source MAG, so the time required for the handover and the allowable time It is possible to switch the execution of buffering according to the delay time.

  (6) Further, the MAG control program of the present invention is a MAG applied to a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. A process for notifying the handover destination MAG of the handover execution of the mobile terminal when receiving a notification from the subordinate mobile terminal in the MAG. A series of processes including a process of notifying the destination MAG of information indicating an application used by the mobile terminal, and a process of establishing a bidirectional tunnel with the destination MAG. It is characterized by being commanded to be readable and executable on a computer.

  In this way, information indicating the application used by the mobile terminal is notified to the destination MAG, so the destination MAG calculates an allowable delay time according to the application of the mobile terminal, and performs buffering. Packets whose allowable delay time has elapsed since the start can be discarded in the order received. As a result, it is possible to effectively use the buffer amount held by the destination MAG, and to prevent deterioration in communication quality of a mobile terminal using a real-time application with a low tolerance for delay. . Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

  (7) The MAG control program of the present invention is a MAG that is applied to a radio access network configured by a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. In the MAG, when the MAG is notified of information indicating the implementation of the handover of the mobile terminal and the application used by the mobile terminal from another MAG communicating with the mobile terminal, the radio Based on the traffic input / output to / from the access network, the application accepts the application based on the process of estimating the time required for handover by the mobile terminal and the information indicating the estimated time required for handover and the notified application. A process for identifying an allowable delay time to be performed, and the estimated hand job Buffering the packet received from the source MAG if the allowable delay time is longer than the estimated time required for the handover as a result of the comparison If the allowable delay time is shorter than the estimated time required for the handover as a result of the comparison, a process for stopping buffering of the packet received from the source MAG, and the buffering A process of discarding packets that have passed the allowable delay time from the start in the order received, and a process of transferring the buffered packets to the mobile terminal when the mobile terminal is connected A series of processes is commanded to be readable and executable by a computer.

  In this way, the allowable delay time is calculated according to the application of the mobile terminal, and after the buffering is started, the packets that have passed the allowable delay time are discarded in the order received, so the buffer held by the destination MAG It is possible to effectively use the amount, and it is possible to prevent deterioration in communication quality of a mobile terminal that uses a real-time application with a low tolerance for delay. Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

  According to the present invention, the allowable delay time is calculated according to the application of the mobile terminal, and after the buffering is started, the packets that have passed the allowable delay time are discarded in the received order. It is possible to effectively utilize the buffer amount to be used, and to prevent the communication quality of a mobile terminal using a real-time application having a low tolerance for delay from being deteriorated. Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

It is a figure which shows the network structure which concerns on this embodiment. It is a figure which shows the procedure of PFMIP Predictive type | mold fast handover. It is a flowchart which shows the procedure of the handover control method which concerns on this embodiment.

  FIG. 1 is a diagram illustrating a network configuration according to the present embodiment. The FPMIP includes an LMA (Local Mobility Anchor) 10, a PMAG (Previous Mobile Access Gateway) 20, an NMAG (Next Mobile Access Gateway) 30, and an MN (Mobile Node) 40. It is assumed that the mobile terminal (MN) 40 uses a service managed by an IMS (IP Multimedia Subsystem). Further, the MAG (Mobile Access Gateway) has an IMS AGW (Access Gateway) function, and performs a gate opening / closing process of an application used by a user in a physical IF (Inter Face). The MAG (PMAG20, NMAG30) can measure the traffic input / output to the connected mobile terminal 40. The mobile terminal 40 performs a PFMIP Predictive handover. In MAG (20, 30), an allowable bandwidth is set in advance for each application.

  In the present embodiment, when the mobile terminal 40 performs a handover in the PFMIP Predictive method, the information of the application used by the mobile terminal 40 when the data transfer tunnel is established between the MAGs is transmitted from the PMAG 20. Notify NMAG 30. The NMAG 30 estimates the handover time according to the characteristics of the radio access network from the traffic input / output to / from the connected mobile terminal. Further, when the mobile terminal 40 performs a handover using the PFMIP Predictive method, the NMAG 30 controls the buffer amount according to the allowable bandwidth of the application being used.

  When the mobile terminal 40 executes a handover, the packet is buffered in the NMAG 30, so that the transfer delay of traffic discharged from the buffer increases. For real-time applications, a delay value acceptable as an application is defined in advance. A packet exceeding such an allowable value is equivalent to a substantial packet loss for the application. Also, when a shared media type wireless access network such as a wireless LAN is assumed, an excessively buffered packet degrades the communication quality of other terminals. For this reason, when buffering is performed on the traffic of a mobile terminal that is handed over by MAG, it is necessary to limit the buffer amount.

  The MAG manages input traffic and output traffic of the connected mobile terminal. The handover time of a mobile terminal moving to the radio access network can be estimated from the relationship between the traffic input to the radio access network and the traffic to be output. In this embodiment, information on the characteristics of the radio access network is registered in the MAG in advance, and it is possible to estimate the handover time at a certain time from the input / output traffic of each mobile terminal connected at a certain time. It is.

  If the time required for the handover of the mobile terminal 40 is known, if the time exceeds the allowable delay time of the application, the NMAG 30 does not perform buffering for the first transferred packet at the time of handover, and Buffer resources can be used effectively.

  FIG. 3 is a flowchart showing a procedure of the handover control method according to the present embodiment. First, the mobile terminal 40 notifies the PMAG of the execution of the handover (step S1). Next, upon receiving notification from the mobile terminal 40 that the handover is to be performed, the PMAG 20 notifies the NMAG 30 that the handover of the mobile terminal 40 is being performed, and the mobile terminal 40 uses the NMAG 30 to perform the handover. Information indicating the current application is notified (step S2). Then, a bidirectional tunnel is established between PMAG 20 and NMAG 30 (step S3).

  Next, the NMAG 30 estimates the time T1 required for the mobile terminal 40 to perform handover based on the traffic input / output to / from the radio access network (step S4). Further, the allowable delay time T2 allowed by the application is specified based on the time T1 required for the handover and the information indicating the application notified in step S2 (step S5).

  Next, the time T1 required for the handover is compared with the allowable delay time T2 allowed by the application (step S6). As a result of this comparison, if the allowable delay time T2 is longer than the time T1 required for the handover, that is, if “YES” in step S6, buffering of the packet received from the PMAG 20 is executed (step S8). On the other hand, if the allowable delay time T2 is shorter than the time T1 required for the handover, that is, if “NO” in step S6, the NMAG 30 stops (does not execute) buffering of the packet received from the PMAG 20 ( Step S7).

  Next, in step S8, the NMAG 30 determines whether or not an allowable delay time has elapsed during execution of buffering (step S9). If the allowable delay time has not elapsed in step S9, the process proceeds to step S11. On the other hand, if the allowable delay time has elapsed in step S9, the NMAG 30 discards the packets in the order received (step S10). Next, when the mobile terminal 40 is connected to the NMAG 30, the NMAG 30 transfers the buffered packet to the mobile terminal 40 (step S11) and ends.

  The characteristic operation of the present embodiment as described above can be realized by causing a computer to execute a control program. That is, the MAG control program according to this embodiment is a MAG that is applied to a radio access network configured by a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. A control program that, in the MAG, receives a notification from the subordinate mobile terminal that a handover is to be performed, a process of notifying the handover destination MAG of the handover of the mobile terminal; A series of processes including a process of notifying a destination MAG of information indicating an application used by the mobile terminal and a process of establishing a bidirectional tunnel with the destination MAG It is characterized by being readable and executable as a command.

  In this way, information indicating the application used by the mobile terminal is notified to the destination MAG, so the destination MAG calculates an allowable delay time according to the application of the mobile terminal, and performs buffering. Packets whose allowable delay time has elapsed since the start can be discarded in the order received. As a result, it is possible to effectively use the buffer amount held by the destination MAG, and to prevent deterioration in communication quality of a mobile terminal using a real-time application with a low tolerance for delay. . Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

  In addition, the MAG control program according to the present embodiment is a MAG that is applied to a radio access network configured by a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs. In the control program, when the MAG is notified of information indicating the implementation of the handover of the mobile terminal and the application used by the mobile terminal from another MAG communicating with the mobile terminal, the radio access Based on the traffic input / output to / from the network, the application permits based on the process for estimating the time required for the mobile terminal to perform a handover, and the estimated time required for the handover and the information indicating the notified application. A process for identifying an allowable delay time and the estimated hand; And when the allowable delay time is longer than the estimated time required for the handover as a result of the comparison, a buffer for a packet received from the source MAG A process of executing a ring, a process of stopping buffering of a packet received from the source MAG when the allowable delay time is shorter than a time required for the estimated handover as a result of the comparison, and the buffering A process of discarding packets in which the allowable delay time has passed since the start of reception, and a process of transferring the buffered packet to the mobile terminal when the mobile terminal is connected. A series of processes including the above are characterized by being computerized so as to be readable and executable by a computer.

  In this way, the allowable delay time is calculated according to the application of the mobile terminal, and after the buffering is started, the packets that have passed the allowable delay time are discarded in the order received, so the buffer held by the destination MAG It is possible to effectively use the amount, and it is possible to prevent deterioration in communication quality of a mobile terminal that uses a real-time application with a low tolerance for delay. Further, when the destination MAG is a shared medium such as a wireless LAN, communication with other terminals connected to the radio access network by discarding unnecessary packets and buffering in the destination MAG at the time of handover. It becomes possible to prevent deterioration in quality.

  As described above, according to the present embodiment, the buffer amount held by the MAG can be effectively used. In addition, it is possible to prevent the communication quality of a mobile terminal using a real-time application having a low tolerance for delay from being significantly reduced due to the discharge of buffered traffic. When the destination access network is a shared medium such as a wireless LAN, the communication quality of other terminals connected to the wireless access network is not greatly lowered by buffering in NMAG at the time of handover.

10 LMA
20 PMAG
30 NMAG
40 Mobile terminal

Claims (7)

Handover of a mobile terminal performed between a source MAG and a destination MAG in a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs A handover control method for controlling
In the source MAG,
Notifying the destination MAG of the handover of the mobile terminal when receiving a notification from the mobile terminal that the handover is to be performed;
Notifying the destination MAG of information indicating an application used by the mobile terminal;
Establishing a bidirectional tunnel with the destination MAG;
In the destination MAG,
Estimating the time required for the mobile terminal to perform a handover based on traffic input to and output from the radio access network; and
Identifying an allowable delay time allowed by the application based on the estimated time required for the handover and information indicating the notified application;
Comparing the estimated time required for handover with the allowable delay time;
As a result of the comparison, if the allowable delay time is longer than the estimated time required for handover, buffering the packet received from the source MAG; and
Discarding packets that have passed the allowable delay time from the start of buffering in the order received;
And at least a step of transferring the buffered packet to the mobile terminal when the mobile terminal is connected.   The destination MAG stops buffering of a packet received from the source MAG when the allowable delay time is shorter than the estimated time required for the handover as a result of the comparison. The handover control method according to 1. A MAG applied to a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs,
When receiving a notification from the subordinate mobile terminal that the handover is to be performed, the handover destination MAG is notified of the handover of the mobile terminal, and the mobile terminal A MAG that notifies information indicating an application being used and establishes a bidirectional tunnel with the destination MAG. A MAG applied to a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs,
When other MAGs in communication with the mobile terminal are notified of information indicating the implementation of the handover of the mobile terminal and the application used by the mobile terminal, based on the traffic input to and output from the radio access network, Estimating the time required for handover by the mobile terminal;
Based on the estimated time required for the handover and the information indicating the notified application, an allowable delay time allowed by the application is specified,
Comparing the estimated time required for handover with the allowable delay time;
As a result of the comparison, if the allowable delay time is longer than the estimated time required for the handover, buffering of the packet received from the source MAG is performed,
Discard the packets that have passed the allowable delay time after starting the buffering in the order received,
The MAG, wherein the buffered packet is transferred to the mobile terminal when the mobile terminal is connected.   5. The MAG according to claim 4, wherein, as a result of the comparison, when the allowable delay time is shorter than the estimated time required for the handover, buffering of the packet received from the source MAG is stopped. A MAG control program applied to a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs,
In the MAG,
A process of notifying the handover destination MAG of the handover execution of the mobile terminal when receiving a notification from the subordinate mobile terminal that the handover is to be performed;
A process of notifying the destination MAG of information indicating an application used by the mobile terminal;
A control program for a MAG, wherein a series of processes including a process for establishing a bidirectional tunnel with the destination MAG is commanded to be readable and executable by a computer. A MAG control program applied to a radio access network composed of a plurality of MAGs (Mobile Access Gateways) and LMAs (Local Mobility Anchors) that manage the MAGs,
In the MAG,
When other MAGs in communication with the mobile terminal are notified of information indicating the implementation of the handover of the mobile terminal and the application used by the mobile terminal, based on the traffic input to and output from the radio access network, A process for estimating a time required for the mobile terminal to perform a handover;
A process for identifying an allowable delay time allowed by the application based on the estimated time required for the handover and information indicating the notified application;
A process of comparing the estimated time required for the handover with the allowable delay time;
As a result of the comparison, when the allowable delay time is longer than the estimated time required for the handover, a process of buffering the packet received from the source MAG;
As a result of the comparison, when the allowable delay time is shorter than the estimated time required for the handover, a process of stopping buffering of the packet received from the source MAG;
A process of discarding packets that have passed the allowable delay time after starting the buffering in the order received;
A series of processes including a process of transferring the buffered packet to the mobile terminal when the mobile terminal is connected is commanded to be readable and executable by a computer. Control program.

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