Freescale Semiconductor MPC8313E PowerQUICC II Pro Family Reference Manual page 898

Enhanced Three-Speed Ethernet Controllers
Preamble
Octet
1
0 0
The sample point coincides with the cycle after the SFD (Start of Frame Delimiter) detection by the MAC.
For received frames, this will be at least 4 bit times (MII) or 8 bit times (GMII) after the message
timestamp point specified in [1588]. For transmission, the eTSEC sample point precedes the sample point
specified in [1588] by at least 4-bit times (MII) or 8-bit times (GMII). For a particular mode, the eTSEC
sample point is a consistent number of bit times relative to the SFD detection. Thus, the offset from the
[1558] specified sample point can be accounted for in the PTP software implementation.
15.6.6.4 PTP Packet Parsing
PTP packets are typically embedded within a UDP payload with special IP source and destination address
and special source and destination ports numbers. Special fields of interest of a PTP packet are listed in
Table 15-160.
Octet
Layer (Offset from
the SFD)
Ethernet 12-13
IP header 22
IP header 23
IP header 26-29
MPC8313E PowerQUICC™ II Pro Integrated Processor Family Reference Manual, Rev. 2
15-180
Message Timestamp
Point
Ethernet
Start of Frame
Delimiter
1 1 1
0 0 0
Figure 15-140. Ethernet Sampling Points for 1588
Table 15-160. PTP Payload Special Fields
Field
Length/Packet
Time to live
IP Protocol
Source IP Address
IANA defines 4 multicast
address for the PTP packet
1 1 1 1
0 0
Bit Time
eTSEC filer
Value
ETY-RQPFR[P
0x0800
RBIFX- choose
0x00 an arbitrary
extraction byte
L4P-RQPFR[P
0x11
SIA-RQPFR[PI
First Octet
Following
Start of Frame
0 0 0 0 0 0
Comments
PID
IPv4
ID=0111]
Must be 0
UDP
ID=1011]
D=1101]
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