Low Latency 50G Ethernet Intel® FPGA IP User Guide: Stratix® 10 Devices

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ID 683675
Date 4/09/2024
Public
Document Table of Contents
Document Table of Contents x
1. About the Low Latency 50G Ethernet IP Core 2. Getting Started 3. Low Latency 50G Ethernet Intel® FPGA IP Parameters 4. Functional Description 5. Interfaces and Signal Descriptions 6. IP Core Register Descriptions 7. Document Revision History for the Low Latency 50G Ethernet Intel® FPGA IP User Guide: Stratix® 10 Devices
1. About the Low Latency 50G Ethernet IP Core x
1.1. Release Information 1.2. Supported Features 1.3. Device Family Support 1.4. Device Speed Grade Support 1.5. IP Core Verification 1.6. Performance and Resource Utilization
1.5. IP Core Verification x
1.5.1. Simulation Environment 1.5.2. Compilation Checking 1.5.3. Hardware Testing
2. Getting Started x
2.1. Installing and Licensing Intel® FPGA IP Cores 2.2. Specifying the Low Latency 50G Ethernet IP Core Parameters and Options 2.3. Simulating the IP Core 2.4. Generated File Structure 2.5. Integrating Your IP Core in Your Design 2.6. Compiling the Full Design and Programming the FPGA
2.1. Installing and Licensing Intel® FPGA IP Cores x
2.1.1. Intel® FPGA IP Evaluation Mode
2.5. Integrating Your IP Core in Your Design x
2.5.1. Pin Assignments 2.5.2. Adding the Transceiver PLL 2.5.3. Placement Settings for the Low Latency 50G Ethernet IP Core
4. Functional Description x
4.1. TX MAC Datapath 4.2. TX PCS 4.3. RX MAC Datapath 4.4. RX PCS 4.5. Link Fault Signaling Interface 4.6. User Interface to Ethernet Transmission 4.7. Auto Negotiation and Link Training 4.8. Flow Control 4.9. Reset
4.1. TX MAC Datapath x
4.1.1. Frame Padding 4.1.2. Preamble Insertion 4.1.3. Inter-Packet Gap Generation and Insertion
4.3. RX MAC Datapath x
4.3.1. IP Core Preamble Processing 4.3.2. IP Core Strict SFD Checking 4.3.3. IP Core Malformed Packet Handling 4.3.4. Length/Type Field Processing 4.3.5. RX CRC Checking and Dynamic Forwarding
4.3.4. Length/Type Field Processing x
4.3.4.1. Length Checking
4.6. User Interface to Ethernet Transmission x
4.6.1. Order of Transmission 4.6.2. Bit Order For TX and RX Datapaths
4.8. Flow Control x
4.8.1. TX Pause/PFC Flow Control Transmission 4.8.2. XON/XOFF Pause Frames
5. Interfaces and Signal Descriptions x
5.1. TX MAC Interface to User Logic 5.2. RX MAC Interface to User Logic 5.3. Transceivers 5.4. Transceiver Reconfiguration Signals 5.5. Avalon® Memory-Mapped Management Interface 5.6. Miscellaneous Status and Debug Signals 5.7. Reset Signals 5.8. Flow Control Interface
5.4. Transceiver Reconfiguration Signals x
5.4.1. Disabling Background Calibration
6. IP Core Register Descriptions x
6.1. PHY Registers 6.2. TX MAC Registers 6.3. RX MAC Registers 6.4. Flow Control Registers 6.5. Statistics Registers 6.6. Auto-Negotiation and Link Training Registers
6.5. Statistics Registers x
6.5.1. TX Statistics Registers 6.5.2. RX Statistics Registers
6.6. Auto-Negotiation and Link Training Registers x
6.6.1. AN/LT Sequencer Config 6.6.2. AN/LT Sequencer Status 6.6.3. Auto Negotiation Config Register 1 6.6.4. Auto Negotiation Config Register 2 6.6.5. Auto Negotiation Status Register 6.6.6. Auto Negotiation Config Register 3 6.6.7. Auto Negotiation Config Register 4 6.6.8. Auto Negotiation Config Register 5 6.6.9. Auto Negotiation Config Register 6 6.6.10. Auto Negotiation Status Register 1 6.6.11. Auto Negotiation Status Register 2 6.6.12. Auto Negotiation Status Register 3 6.6.13. Auto Negotiation Status Register 4 6.6.14. Auto Negotiation Status Register 5 6.6.15. Link Training Config Register 1 6.6.16. Link Training Config Register 2 6.6.17. Link Training Status Register 1 6.6.18. Link Training Config Register for Lane 0 6.6.19. Link Training Frame Contents for Lane 0 6.6.20. Local Transceiver TX EQ 1 Settings for Lane 0 6.6.21. Local Transceiver TX EQ 2 Settings for Lane 0 6.6.22. Local Link Training Parameters 6.6.23. Link Training Config Register for Lane 1 6.6.24. Link Training Frame Contents for Lane 1 6.6.25. Local Transceiver TX EQ 1 Settings for Lane 1 6.6.26. Local Transceiver TX EQ 2 Settings for Lane 1 6.6.27. Link Training Config Register for Lane 2 6.6.28. Link Training Frame Contents for Lane 2 6.6.29. Local Transceiver TX EQ 1 Settings for Lane 2 6.6.30. Local Transceiver TX EQ 2 Settings for Lane 2 6.6.31. Link Training Config Register for Lane 3 6.6.32. Link Training Frame Contents for Lane 3 6.6.33. Local Transceiver TX EQ 1 Settings for Lane 3 6.6.34. Local Transceiver TX EQ 2 Settings for Lane 3
1. About the Low Latency 50G Ethernet IP Core
2. Getting Started
3. Low Latency 50G Ethernet Intel® FPGA IP Parameters
4. Functional Description
5. Interfaces and Signal Descriptions
6. IP Core Register Descriptions
7. Document Revision History for the Low Latency 50G Ethernet Intel® FPGA IP User Guide: Stratix® 10 Devices

4.8. Flow Control

Flow control reduces congestion at the local or remote link partner. When either link partner experiences congestion, the respective transmit control sends pause frames. XOFF Pause frames stop the remote transmitter. XON Pause frames let the remote transmitter resume data transmission. Flow control supports both Pause and Priority Flow Control (PFC) control frames:
  • IEEE 802.3 flow control—implements the IEEE 802.3 Annex 31B standard to manage congestion. This flow control is a mechanism to manage congestion at the local or remote partner. When the receiving device experiences congestion, it sends an XOFF pause frame to the emitting device to instruct the emitting device to stop sending data for a duration specified by the congested receiver. Data transmission resumes when the emitting device receives an XON pause frame (pause quanta = zero) or when the timer expires.
  • Priority-based flow control (PFC)—implements the IEEE 802.1Qbb standard. PFC manages congestion based on priority levels. It supports up to 8 priority queues. When the receiving device experiences congestion on a priority queue, it sends a PFC frame requesting the emitting device to stop transmission on the priority queue for a duration specified by the congested receiver. When the receiving device is ready to receive transmission on the priority queue again, it sends a PFC frame instructing the emitting device to resume transmission on the priority queue.
Figure 14. Flow Control Module Conceptual OverviewThe flow control module acts as a buffer between client logic and the TX and RX MAC.

Flow Control includes the following features:

  • Pause or PFC frame generation and transmission:
    • Configurable selection of standard or priority-based flow control
    • Programmable 1- or 2-bit XON/XOFF request mode
    • In 2-bit request mode, programmable selection of register or signal-based control
    • Programmable per-queue XOFF frame separation
    • Programmable destination and source addresses in outgoing pause and PFC frames
    • Programmable pause and PFC quanta
  • Client versus Pause or PFC frame transmission based on a priority-based arbitration scheme with frame-type indication for external downstream logic
  • Stopping the next client frame transmission on the reception of a valid Pause frame
  • Stopping the per queue client frame transmission on the reception of a valid PFC frame from the client. Includes per-queue PFC Pause quanta duration indicator
  • Pause or PFC frame reception and decode:
    • Programmable destination address for filtering incoming pause and PFC frames
    • Configurable Pause or PFC per-queue enable, directing the IP core to ignore incoming pause frames on disabled queues
    • Per-queue client frame transmission pause duration indicator
CAUTION:
The Low Latency 50G Ethernet core supports the flow control feature for either value of the Ready Latency parameter. However, in standard flow control you might experience data delay if you select the value of 3 for this parameter. In standard flow control, data might be delayed in the IP core if transmission stops while data is in the ready latency buffer. This issue does not occur in priority-based flow control.

Section Content
TX Pause/PFC Flow Control Transmission
XON/XOFF Pause Frames

Level Two Title