GFP-T vs GFP-F | Difference between GFP-T and GFP-F

This page compares GFP-T vs GFP-F and mentions difference between GFP-T and GFP-F modes. GFP is the short form of Generic Frame Protocol.

These are two adaptation modes used to carry client data in the GFP frames. GFP-F is applicable to most packet data types. GFP-T is applicable to 8B/10B coded signals.

GFP-F mode

• GFP-F maps each client frame into single GFP frame. GFP-F is used where client signal is framed or packetized by client protocol.
• GFP-F is the short form of Frame Mapped GFP.
• It is good for PDU-based protocols viz. ethernet, IP, MPLS or HDLC based protocols viz. PPP.
• Client PDU is placed in GFP payload field.

GFP-T mode

• GFP-T allows mapping of multiple 8B/10B block coded client data streams into an efficient 64B/65B block code for transport within a GFP frame.
• GFP-T is the short form of Transparent GFP.
• It is good for protocols which exploit physical layer capabilities.
• GFP-T is transparent to codes such as 8B/10B, GbE, FICON, ESCON, DVB etc. Moreover GFP-T need not require entire PDU to be received.

The figure-1 depicts GFP-F and GFP-T frame structures. Following table mentions comparison GFP-T and GFP-F modes.

Specifications	GFP-T	GFP-F
Full form	Transparent GFP	Frame mapped GFP
Function	It maps bytes from frame to SONET frames.	It maps frames (such as ethernet) to SONET frames.
Protocol transparency	High	Low
Efficiency	Low	High
Encapsulation protocol level	Layer-1 (PHY)	Layer-2 (PDU)
Isocronic or delay sensitive	YES	NO
Optimized for	SAN, DVB	Ethernet
Statistical multiplexing of several client signals	NO	YES
SAN transport	YES	NO
Ethernet transport	POSSIBLE	OPTIMUM