RapidIO Intel FPGA IP User Guide

ID 683884
Date 9/15/2021
Public
Document Table of Contents

4.3.6.2. Error Conditions Flagged for the Transport Layer

The Physical layer passes data from the receive buffer to the Transport layer in 64-Kbyte blocks. The Physical layer might identify an error condition after it begins passing a packet from the receive buffer to the Transport layer. In that case, the Physical layer flags an Errored packet indication to the Transport layer. The Physical layer flags an Errored packet in the following cases:
  • CRC error—when a CRC error is detected, the packet_crc_error signal is asserted for one rxclk clock period. If the packet size is at least 64 bytes, the Physical layer flags the error. If the packet size is less than 64 bytes, the Physical layer identifies and drops the errored packet before it begins sending the packet to the Transport layer.
  • Stomp—the Physical layer flags an error if it receives a stomp control symbol in the midst of a packet, causing the packet to be prematurely terminated.
  • Packet size—if a received packet exceeds the allowable size, the Physical layer cuts it short to the maximum allowable size (276 bytes total), and flags the error.
  • Outgoing symbol buffer full—under some congestion conditions, the outgoing symbol buffer has no space available for the packet_accepted control symbol. In this case, the RapidIO IP core cannot acknowledge the packet, and the link partner must retry transmission. The Physical layer flags an error to indicate to the Transport layer that it should ignore the received packet because it will be retried.
  • Control symbol error —if an embedded or packet-delimiting control symbol is errored, the Physical layer flags the error. The packet in which the errored control symbol is embedded should be retransmitted by the link partner as part of the error recovery process.
  • Character error—if the Physical layer receives an errored character (an invalid 10-bit code, or a character of wrong disparity) or an illegal character (any control character other than the non-delimiting Start of Control (SC) character inside a packet) within a packet. In this case the Physical layer flags the error and drops the rest of the packet.