Transaction ID (4 bytes) (FDDI)

Protocol: FDDI - SMT Header FDDI SMT PCI

Field: transaction ID

Length: 4 bytes

Contents: request frame identification number.

Each request frame (Frame Class (1 byte) (FDDI) / Frame Type (1 byte) (FDDI)) is sent with a unique frame identifier = transaction ID. This tansaction ID should not be mixed up with common sequence numbers because they are not incremented in a chain of frames. The FDDI SMT transaction ID is a random number.

The SMT response must repeat the transaction ID.

SMT frames don't have highest transmission priority as real timie applications. Therefore, there may be multiple outstanding SMT requests that must be identified by their transaction ID.