Nak Errors

Introduction

Under certain error conditions, the responder QP's RQ Logic returns a Nak (Negative Ack) rather than a positive Ack, an RDMA Read response, or an Atomic response. The following types of RC-related Naks are currently defined in the specification:

  • PSN Sequence Error Nak. May be retried.

  • Remote Access Error Nak. Results in an error completion and may not be retried.

  • Invalid Request Nak. Results in an error completion and may not be retried.

  • Remote Operational Error Nak. Results in an error completion and may not be retried.

  • Receiver Not Ready (RNR) Nak. May be retried.

Nak Packet Format

A Nak packet consists of Ack packet (see Figure 17-6 on page 369) containing a Nak error code (see Table 17-3 on page 370 and Table 17-4 ...

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