Link Packet (Flow Control Packet) Check
by MindShare, Inc., Tom Shanley
InfiniBand Network Architecture
- Copyright
- PC System Architecture Series
- Figures
- Tables
- Acknowledgments
- About This Book
- Core Concepts
- QP Creation and Operation
- Protection Mechanisms
- Detailed Description of the Transport Services
- RC Transport Service
- RC Support Requirement
- RC Basic Operational Characteristics
- RC Connection Establishment
- Packet Opcodes
- RC Message Transfer Primer
- Structure of This Discussion
- QP State before Any Messages Are Transferred
- Standard Operation in Fast, Error-Free Environment
- Traffic Reduction
- Packet Delivery Delays
- Packet Loss
- Nak Errors
- RQ Logic's Error Detecting and Handling
- End-to-End Flow Control
- SQ Logic Can Use MSN to Complete WQEs
- Additional Reference Information
- UC Transport Service
- RD Transport Service
- UD Transport Service
- Raw Transport Service Types
- Goal: Tunneling Non-IBA Packets through IBA Network
- Solution: Disguise It as Special-Purpose IBA Packet
- Raw QPs Are Used to Transmit/Receive Non-IBA Packets
- Raw QP Support Requirement
- Raw Transport Services Are Unreliable
- Send and Receive Are Only Supported Operation Types
- Basic Operational Description
- Raw Datagrams Do Not Have an ICRC
- Raw Datagrams Do Not Have a Destination QP
- LRH:LNH Indicates Packet Type
- Raw IPv6 Datagrams
- Raw EtherType Datagrams
- Additional Reference Material
- Multicasting
- Automatic Path Migration
- Static Rate Control
- RC Transport Service
- Link and Physical Layer Descriptions
- Detailed Description of the Link Layer
- Link Layer Functional Overview
- Link State Machine
- Detailed Description of LRH
- QoS within the Subnet: SL and VLs
- Detailed Description of VL Arbitration
- Link-Level Flow Control
- Packet CRCs
- Intro to the Packet Delimiters
- Packet Receive State Machine
- Data Packet Check
- Link Packet (Flow Control Packet) Check
- Switch Performs Packet Forwarding
- Overview of Router Port's Link Layer
- Detailed Physical Layer Description
- Detailed Description of the Link Layer
- The SM and SA
- The SMI
- Purpose of the SMI (QP0)
- The SMI on a CA and Router
- The SMI on Switches
- Detailed Switch Handling of SMPs
- Detailed CA or Router Handling of SMPs
- SM Wishes to Access an Attribute in Its Local Device
- SM Can Reside in a Switch
- SMI Is a Privileged Resource
- SMI Only Communicates with Other SMIs
- Port States SMPs Can Be Sent and Received In
- SMPs Never Leave the Subnet
- Setting Up an HCA Port's SMI
- How the SM Sends a Message and Handles a Response
- SMP Source and Destination
- The SMI and the Q_Key
- The SMI and Partitions
- Additional Reference Material
- Detailed Description of MADs
- SM Methods and Attributes
- Multiple SMs
- Discovery
- The GSI
- Detailed Description of SA
- Purpose of the SA
- SA Accessed Using GMPs
- Location of the SA
- Requester Access Authorization
- SA Methods and Attributes
- Record Identifier (RID) Definition
- SubnAdmGet() Operation
- SubnAdmSet() Operation
- Definition of a Table
- SubnAdmConfig() Operation
- Database Queries Using SubnAdmGetTable()
- Fetch Entire Database
- Reliable Multi-Packet Transaction Protocol
- Additional Reference Information
- The SMI
- General Services
- Baseboard Management
- Roles of the Other Managers
- The BM Reaches behind the IBA Front-End
- Chassis and Module
- Chassis Baseboard Management Elements
- Passively Managed Chassis
- Module BM Elements
- Non-Module IBA Devices
- BM MAD Format
- BM Methods
- BM Attributes
- BM Sending a Command to the MME
- CME Sends a Command to the BM
- BM-related Traps
- Performance Management
- Communications Management
- Device Management
- Glossary
- Baseboard Management
- Index
Link Packet (Flow Control Packet) Check
Refer to Figure 25-21 on page 661. A port's Link Layer performs the checks shown in the figure before passing the packet to the Link Layer's Flow Control logic for placement in the designated VL receive buffer.
Figure 25-21. Link Layer's Link Packet Check
During initialization, the number of active VLs may not have been configured yet, so receiving credits for a unsupported VL is only an error if the Link Layer is in the LinkArm or LinkAct state. See “Link State Machine” on page 602.
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