Difference between the GE and GFP-T service modes

GE (GFP-F) can detect and respond to negotiation packets of the Ethernet working mode. It supports autonegotiation. GE (GFP-T), like an optical fiber, implements negotiation of the Ethernet working mode between the data devices interconnected with the TOM boards.

The TTT-GMP encapsulation mode can better support synchronous Ethernet, and GFP-T can transparently transmit data packets with low latency.

GFP (an encapsulation protocol) defines two client signal adaptation modes: Frame-Mapped GFP (GFP-F): GFP-F is a PDU-oriented processing mode. It encapsulates the entire PDU into the GFP payload area and makes no modification on the encapsulated data. It determines whether to add a detection area for the payload area, depending on requirements. Transparent GFP (GFP-T): GFP-T is a block-code (8B/10B code block) oriented processing mode. It extracts a single character from the received data block and maps the character into the fixed-length GFP frame.

TTT-GMP and GFP-T are two encapsulation modes of GE services. They are different in physical clock synchronization modes and transcoding modes. GFP-T implements timing transparent transcoding (TTT). TTT-GMP complies with ITU-T G.709, and implements asynchronous transcoding.

In the GFP-T encapsulation mode, the client-side port does not perform negotiation with the TOA boards. Instead, client devices at two ends negotiate with each other directly. In the GMP-PPP encapsulation mode, the client-side device performs negotiation with the TOA boards.