Export of RoCEv2 Base Transport Header (BTH) Information Using IP Flow Information Export (IPFIX)

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Table of Contents

1. Introduction

Remote Direct Memory Access (RDMA) [RFC5040] is a network technology that allows a computer to read from or write to the memory of another computer directly, without involving the operating system. This zero-copy and kernel-bypass feature greatly reduces CPU overhead and communication latency. InfiniBand [IBTA-SPEC] and RDMA over Converged Ethernet (RoCE) are two mainstream RDMA implementations that bypass the operating system kernel and achieve zero-copy data transfer.¶

RoCE technology has become a key component of high-performance data center networks, especially in low-latency, high-throughput scenarios such as artificial intelligence training, distributed storage, and financial transactions. RDMA over Converged Ethernet version 2 (RoCEv2) runs on top of UDP (port 4791) and inherits the transport layer protocol of the InfiniBand Architecture (IBA).¶

The existing IPFIX [RFC7011] standard lacks the ability to monitor specific fields of RoCEv2, which limits the ability of network operators to perform in-depth analysis, troubleshooting, and performance optimization of RDMA traffic. To close this gap, this document defines a new set of Information Elements (IEs) to carry RoCEv2 BTH key fields.¶

2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶

The following terms are used as defined in [RFC7011]:¶

• IPFIX¶
• IPFIX Information Elements¶

The following terms are used in this document:¶

• QP: Queue Pair, a communication endpoint in RDMA architecture.¶
• BTH: Base Transport Header, the RDMA transport header containing QP information.¶
• P_Key: Partition Key.¶
• PSN: Packet Sequence Number.¶

3. New IPFIX Information Elements for RoCEv2 BTH

This section defines new IPFIX IEs for exporting RoCEv2 BTH key fields.¶

rdmaOpCode

The RoCEv2 BTH OpCode field, which indicates the type of the InfiniBand Architecture data packet.¶

rdmaPartitionKey

The RoCEv2 BTH Partition Key field, which identifies the logical partition to which the data packet belongs.¶

rdmaDestinationQP

The RoCEv2 BTH Destination Queue Pair (QP) field, indicating the work QP number at the destination.¶

rdmaSourceQP

The RoCEv2 BTH Source Queue Pair (QP) field (if present), indicating the work QP number at the Source.¶

rdmaPacketSequenceNumber

The RoCEv2 BTH Packet Sequence Number (PSN) field, which is used to detect whether data packets are lost or duplicated, ensuring the reliability and orderliness of transmission.¶

rdmaBTHFlags1

The SE, M, Pad, and TVer fields of The RoCEv2 BTH. The size of this Information Element is 1 octet.¶

rdmaBTHFlags2

The F/R, and B/R fields of The RoCEv2 BTH. The size of this Information Element is 1 octet.¶

rdmaBTHFlags3

The A field of The RoCEv2 BTH. The size of this Information Element is 1 octet.¶

4. Operational Considerations

The exporter needs to parse RoCEv2 BTH information, which may affect the exporter's performance. Implementers SHOULD consider measures to mitigate this impact, such as sampling rate limiting or hardware acceleration.¶

5. Security Considerations

The Security Considerations for IPFIX [RFC7011] apply to this document as well.¶

When exporting RDMA BTH information across security domains, to prevent information security risks caused by the leakage of sensitive network topology details such as QP numbers, it is recommended to implement comprehensive protection measures, such as using the encrypted transmission options of the IPFIX framework (such as DTLS [RFC9147]) to ensure the confidentiality and integrity of data during transmission.¶

To defend against Denial-of-Service (DOS) attacks that may be caused by maliciously crafted RoCEv2 packets and to prevent the exporter from being overloaded by processing a large amount of invalid traffic, it is recommended to adopt certain protection strategies, such as configuring reasonable rate limiting policies to prevent the monitoring system from being overwhelmed by massive data packets and to ensure its stable operation.¶

6. IANA Considerations

   +============+==========================+===============+
   | Element ID | Name                     | Reference     |
   +============+======================--==+===============+
   | TBD1       | rdmaOpCode               | This document |
   +------------+--------------------------+---------------+
   | TBD2       | rdmaPartitionKey         | This document |
   +------------+--------------------------+---------------+
   | TBD3       | rdmaDestinationQP        | This document |
   +------------+--------------------------+---------------+
   | TBD4       | rdmaSourceQP             | This document |
   +------------+--------------------------+---------------+
   | TBD5       | rdmaPacketSequenceNumber | This document |
   +------------+--------------------------+---------------+
   | TBD6       | rdmaBTHFlags1            | This document |
   +------------+--------------------------+---------------+
   | TBD7       | rdmaBTHFlags2            | This document |
   +------------+--------------------------+---------------+
   | TBD8       | rdmaBTHFlags3            | This document |
   +------------+--------------------------+---------------+

Table 1: New IEs in the "IPFIX Information Elements" Registry

Authors' Addresses