|  | 4.1 | PPP
| 4.1.4 | The six fields of a PPP frame

As shown in the Figure, the fields of a PPP frame are as follows: Flag-Indicates the beginning or end of a frame and consists of the binary sequence 01111110. Address - Consists of the standard broadcast address, which is the binary sequence 11111111. PPP does not assign individual station addresses. Control - 1 byte that consists of the binary sequence 00000011, which calls for transmission of user data in an unsequenced frame. A connection-less link service similar to that of Logical Link Control (LLC) Type 1 is provided. Protocol - 2 bytes that identify the protocol encapsulated in the data field of the frame. Data - 0 or more bytes that contain the datagram for the protocol specified in the protocol field. The end of the data field is found by locating the closing flag sequence and allowing 2 bytes for the frame check sequence (FCS) field. The default maximum length of the data field is 1,500 bytes. FCS - Normally 16 bits (2 bytes). Refers to the extra characters added to a frame for error control purposes.
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