Section: 5 GTP Header for Control Plane 5.1 General format
Content: Control Plane GTP uses a variable length header. Control Plane GTP header length shall be a multiple of 4 octets. Figure 5.1-1 illustrates the format of the GTPv2-C Header. Figure 5.1-1: General format of GTPv2 Header for Control Plane Where: - if T = 0, TEID field is not present, k = 0, m = 0 and n = 5; - if T = 1, TEID field is present, k = 1, m = 5 and n = 9. The usage of GTPv2-C header across the EPC specific interfaces is defined in the clause 5.5 "Usage of the GTPv2-C Header". Octet 1 bits shall be coded as follows: - Bits 6-8 represent the Version field. - Bit 5 represents the Piggybacking flag (P). - Bit 4 represents the TEID flag (T). - Bits 3-1 are spare, the sender shall set them to "0" and the receiving entity shall ignore them.