Crc_Start_Of_Packet; Crc_End_Of_Packet; Rxcheckingcrc, Rxcrcerr - Xilinx RocketIO User Manual

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R
The CRC is calculated with certain bits masked in LRH and GRH, depending on whether
the packet is local or global. The size of these headers is shown in
Table 2-21: Global and Local Headers
LRH
GRH
BTH
The CRC checks the LNH (Link Next Header) of the LRH. LRH is shown in
along with the bits the CRC uses to evaluate the next packet.
Because of the complexity of the CRC algorithms and implementations, especially with
Infiniband, a more in-depth discussion is beyond the scope of this manual.

CRC_START_OF_PACKET,

CRC_END_OF_PACKET

When implementing USER_MODE CRC, Start of Packet (SOP) and End of Packet (EOP)
must be defined for the CRC logic. These delimiters must be one of the defined
K-characters (see
sequence (CCS) or IDLE sequence; otherwise, the CRC will mistake the CCS or IDLE for
SOP/EOP.
RXCHECKINGCRC,
RXCRCERR
These two signals are status ports for the CRC circuitry.
RXCHECKINGCRC is asserted within several USRCLKs of the EOF being received from
RXDATA. This signals that the CRC circuitry has identified the SOF and the EOF.
If a CRC error occurred, RXCRCERR will be asserted at the same time that
RXCHECKINGCRC goes High.
88
Packet
Local Routing Header
Global Routing Header
IBA Transport Header
− B1
B B1
0 7
1 1 IBA Global Packet
B1 , B1
1 0
1 0 IBA Local Packet
0 1 Raw Packet (CRC does not insert remainder)
0 0 Raw Packet (CRC does not insert remainder)
Figure 2-27: Local Route Header
Note:
Minimum data length for this mode is defined by the protocol requirements.
Table B-2, page
Note:
These attribute are not applicable to the other CRC formats.
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Chapter 2: Digital Design Considerations
Description
B B B B
0 2 3 4 5
143). These must be different than a clock correction
RocketIO™ Transceiver User Guide
Table 2-21.
Size
8 Bytes
40 Bytes
12 Bytes
Figure 2-27,
B B
6 7
UG024_15_020802
UG024 (v3.0) February 22, 2007