Protocol: ISO 8473 / CLNP
PDU Part: Fixed Part
Field: protocol ID
Length: 1 byte
Contents: protocol identifier.
ISO 8473 = '10000001'.
ISO protocols use the following codes to identify network protocols:
10000001 = ISO 8473 - CLNP
10000010 = ISO 9542 - CLNS ES-IS
10001010 = ISO 10030 - CONS ES-IS