Communication method, apparatus, and system

A method, comprising:

• receiving, by a radio access network device from a terminal device, a first message that comprises a part of a context identifier that is obtained after a truncation;
• determining, by the radio access network device based on the first message, whether a remaining part of the context identifier needs to be obtained, wherein the remaining part of the context identifier is obtained after the truncation;
• and
• in response to determining that the remaining part of the context identifier needs to be obtained, sending, by the radio access network device, a request message for the remaining part of the context identifier to the terminal device;
• receiving, by the radio access network device from the terminal device, a third message that comprises the remaining part of the context identifier;
• sending, by the radio access network device, a second message to a core network device, wherein the second message comprises the context identifier;
• and
• receiving, by the radio access network device, context information of the terminal device from the core network device.

A terminal device, comprising:

• a storage medium including executable instructions;
• and
• a processor;
• wherein the executable instructions, when executed by the processor, cause the terminal device to:
• transmit a first message that comprises a part of a context identifier to a radio access network device, wherein the part of the context identifier is obtained after a truncation;
• receive a request message for a remaining part of the context identifier from the radio access network device, wherein the radio access network device determines, based on the first message, whether a remaining part of the context identifier needs to be obtained, and wherein the remaining part of the context identifier is obtained after the truncation;
• and
• transmit, in response to the request message, a third message that comprises the remaining part of the context identifier to the radio access network device.

A method, comprising:

• transmitting, by a terminal device, a first message that comprises a part of a context identifier to a radio access network device, wherein the part of the context identifier is obtained after a truncation;
• receiving, by the terminal device, a request message for a remaining part of the context identifier from the radio access network device, wherein the radio access network device determines, based on the first message, whether a remaining part of the context identifier needs to be obtained, and wherein the remaining part of the context identifier is obtained after the truncation;
• and
• transmitting, by the terminal device, in response to the request message, a third message that comprises the remaining part of the context identifier to the radio access network device.