Communication method and communications apparatus

A target access network device, comprising:

• at least one processor;
• and
• a memory coupled to the at least one processor and configured to store program instructions, which when executed by the at least one processor, cause the target access network device to:
• receive a radio resource control (RRC) resume request from a user equipment (UE), wherein the RRC resume request comprises an inactive-radio network temporary identifier (I-RNTI);
• send a context information obtaining request comprising the I-RNTI to a source access network device;
• receive a context information obtaining response from the source access network device, wherein the context information obtaining response comprises first indication information, wherein the first indication information indicates a user plane security protection method used before the UE enters an inactive state from a connected state, and wherein the user plane security protection method indicates whether at least one of user plane encryption protection or user plane integrity protection is enabled;
• and
• activate, using the user plane security protection method, user plane security between the target access network device and the UE when the user plane security protection method can be supported.

An apparatus, comprising:

• at least one processor;
• and
• a memory coupled to the at least one processor and configured to store program instructions, which when executed by the at least one processor, cause the apparatus to:
• store first indication information, wherein the first indication information indicates a user plane security protection method used before the apparatus enters an inactive state from a connected state, and wherein the user plane security protection method indicates whether at least one of user plane encryption protection or user plane integrity protection is enabled;
• send a radio resource control (RRC) resume request to a target access network device;
• and
• activate, using the user plane security protection method, user plane security between the apparatus and the target access network device when receiving an RRC resume message from the target access network device.

A method comprising:

• receiving, by a target access network device, a radio resource control (RRC) resume request from a user equipment (UE), wherein the RRC resume request comprises an inactive-radio network temporary identifier (I-RNTI);
• sending, by the target access network device, a context information obtaining request comprising the I-RNTI to a source access network device;
• receiving, by the target access network device, a context information obtaining response from the source access network device, wherein the context information obtaining response comprises first indication information, wherein the first indication information indicates a user plane security protection method used before the UE enters an inactive state from a connected state, and wherein the user plane security protection method indicates whether at least one of user plane encryption protection or user plane integrity protection is enabled;
• and
• activating, by the target access network device using the user plane security protection method, user plane security between the target access network device and the UE when the user plane security protection method can be supported.

A method comprising:

• storing, by an apparatus, first indication information, wherein the first indication information indicates a user plane security protection method used before the apparatus enters an inactive state from a connected state, and wherein the user plane security protection method indicates whether at least one of user plane encryption protection or user plane integrity protection is enabled;
• sending, by the apparatus, a radio resource control (RRC) resume request to a target access network device;
• and
• activating, by the apparatus using the user plane security protection method, user plane security between the apparatus and the target access network device when receiving an RRC resume message from the target access network device.

The method according to 28, further comprising:

• determining, by the apparatus, a first user plane security key between the apparatus and the target access network device;
• performing, by the apparatus, user plane security protection on uplink user plane data based on the user plane security protection method and the first user plane security key;
• obtaining, by the apparatus, first uplink user plane data based on performing the user plane security protection on the uplink user plane data;
• and
• sending, by the apparatus, the first uplink user plane data to the target access network device.

A communications method, comprising:

• receiving, by a target access network device, a radio resource control (RRC) resume request from a user equipment (UE), wherein the RRC resume request comprises an inactive—radio network temporary identifier (I-RNTI);
• sending, by the target access network device, a context information obtaining request comprising the I-RNTI;
• receiving, by the source access network device, the context information obtaining request from the target access network device;
• obtaining, by the source access network device, first indication information based on the I-RNTI, wherein the first indication information indicates a user plane security protection method used before the source access network device and the UE enter an inactive state from a connected state, and wherein the user plane security protection method indicates whether at least one of user plane encryption protection or user plane integrity protection is enabled;
• sending, by the source access network device, a context information obtaining response to the target access network device, wherein the context information obtaining response comprises the first indication information;
• receiving, by the target access network device, the context information obtaining response from the source access network device;
• and
• activating, by the target access network device using the user plane security protection method, user plane security between the target access network device and the UE when the user plane security protection method can be supported.