Altera 10-Gbps Ethernet MAC MegaCore Function - Manual (Page 156)

A–4 Appendix A: Frame Format
Priority-Based Flow Control Frame
10-Gbps Ethernet MAC MegaCore Function User Guide February 2014 Altera Corporation
A.4. Priority-Based Flow Control Frame
The PFC frame is an extension of the basic pause frame. It contains additional fields to
enable priority queues and specify pause quanta for these queues.
Figure A–5 shows
the PFC frame format.
The following are the additional fields in the PFC frame:
■ PFC Opcode—a 2-octet fixed value of 0x0101.
■ Pause Quanta Enable[15:0]—indicates the validity of the pause quanta fields. The
upper byte of this field is unused. Each bit in the lower byte represents a priority
queue. If bit n is set to 1, it indicates that pause quanta n is valid and should be
acted upon.
■ Pause Quanta n[15:0]—the pause quanta for priority queue n.
Figure A–5. PFC Frame Format
Destination Address[47:0] = 0x0180C2000001
Source Address[47:0] = MAC Primary Address
Pause Quanta 7[15:0]
6 Octets
6 Octets
2 Octets
PFC Opcode[15:0] = 0x0101
Type[15:0] = 0x8808 2 Octets
2 Octets
Pause Quanta Enable[15:0] = 0x00, e[7:0]
2 Octets Pause Quanta 0[15:0]
Padding[207:0] = 26 bytes of 0x00
26 Octets
Frame Check Sequence[31:0] 4 Octets
Pause Quanta n[15:0] 6 x 2 Octets
2 Octets