Terminal device to determine whether to re-establish a PDCP layer entity based on indication received from a network device

A terminal device comprising:

• a receiving unit, configured to receive configuration information that is used to perform mobility management on the terminal device and that is sent by a network device, wherein the configuration information comprises indication information, and the indication information is used to configure a packet data convergence protocol PDCP layer entity;
• and
• a processing unit, configured to determine, according to the indication information, whether to re-establish the PDCP layer entity,
• wherein the processing unit is further configured to determine, when re-establishing the PDCP layer entity according to the indication information, that a ciphering and deciphering algorithm needs to be reconfigured.

A computer system including:

• one or more processors;
• and
• one or more memories storing computer-readable instructions that, upon execution by the one or more processors, configure the computer system to:
• receive, by a terminal device, configuration information that is used to perform mobility management on the terminal device and that is sent by a network device, wherein the configuration information comprises indication information, and the indication information is used to configure a packet data convergence protocol PDCP layer entity;
• and
• determine, by the terminal device according to the indication information, whether to re-establish the PDCP layer entity,
• wherein the computer-readable instructions further configure the computer system to:
• determine, by the terminal device when the terminal device re-establishes the PDCP layer entity according to the indication information, that a ciphering and deciphering algorithm needs to be reconfigured.