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ROCE (Remote Direct Memory Access over Converged Ethernet) is a network technology that combines the characteristics of RDMA (Remote Direct Memory Access) and Ethernet switches. ROCE allows efficient direct memory access between hosts over Ethernet, providing low-latency, high-throughput data transfers.
When using ROCE, Ethernet switches supporting ROCE need to be deployed in the network. These switches require specific hardware and software support to route, forward and manage RDMA traffic. The existence of ROCE switches can greatly reduce the communication delay between hosts and provide higher bandwidth and throughput.
Switches play a key role in the ROCE network, and they are responsible for forwarding and routing RDMA traffic from different hosts. These switches need to support the RDMA protocol stack, be able to process RDMA-related data packets, and correctly forward them to the corresponding target host according to the destination address.
ROCE switches also need to provide some management functions, such as configuring QoS (Quality of Service), VLAN (Virtual Local Area Network), etc., to ensure the reliability and performance of the network.
In short, switches play a key role as a bridge in the ROCE network, and they are key components to achieve efficient and low-latency data transmission. By using switches that support ROCE, high-performance, scalable RDMA networks can be built on Ethernet.
RDMA
RDMA (Remote Direct Memory Access) is a computer networking technology that allows reading and writing directly from one computer's memory to another computer's memory without consuming CPU resources. This technique can significantly improve the performance of data transfers and reduce latency.
RDMA solves some bottlenecks in traditional network communication methods, such as the complexity of the TCP/IP protocol stack and the load on the processor. It achieves data transfer directly from one host memory to another host memory by using specialized adapters and hardware to bypass the limitations of the operating system and protocol stack.
The following are the main features of RDMA and some of the problems it solves:
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Low Latency: RDMA can reduce the delay of data transmission because it does not need to process data packets through the operating system protocol stack, nor does it need to wait for the CPU to process data. This makes RDMA a great advantage in latency-sensitive applications, such as financial transactions, scientific computing, etc.
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High bandwidth: RDMA can achieve very high data transfer rates because it can directly access host memory without CPU intervention. This is important for large-scale data transfer, high-performance computing, and storage systems.
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Reduce CPU load: RDMA can offload the task of data transmission from the CPU, so that the CPU can focus more on computing tasks and improve overall system performance.
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Zero-copy: RDMA can achieve zero-copy data transmission by bypassing the operating system protocol stack. This means that data does not need to be copied during transmission, reducing the overhead of data transmission.
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Flexibility: RDMA supports multiple transmission protocols, such as InfiniBand, RoCE (RDMA over Converged Ethernet) and iWARP (Internet Wide Area RDMA Protocol), which can adapt to different network environments and requirements.
Although RDMA offers many advantages, it also has some challenges and limitations. For example, RDMA requires special hardware and adapter support, pre-established connections between systems and configured shared memory, etc. In addition, RDMA can be relatively complex to deploy and manage, and requires specialized technical knowledge.
Overall, RDMA is a powerful networking technology that can significantly improve data transfer performance and reduce latency. It is widely used in high-performance computing, storage systems, cloud computing and other fields to provide faster and more reliable data transmission solutions.
RDMA (Remote Direct Memory Access)、RoCE (RDMA over Converged Ethernet)、IB (InfiniBand)、TCP (Transmission Control Protocol) 和 Ethernet 关系
RDMA (Remote Direct Memory Access), RoCE (RDMA over Converged Ethernet), IB (InfiniBand), TCP (Transmission Control Protocol), and Ethernet are some terms related to data center networking and high performance computing. There are some direct relationships between them, let's explain them one by one.
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Ethernet : It is a common local area network technology used to transfer data between computers and other devices. Ethernet uses frames to encapsulate data and uses MAC addresses for addressing.
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TCP : It is a connection-oriented protocol that provides reliable data transmission. TCP works on the basis of IP (Internet Protocol) and utilizes mechanisms such as sequence number, acknowledgment and retransmission to ensure the integrity and order transmission of data.
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IB : InfiniBand is a high-performance interconnect technology commonly used to build high-performance computing and storage networks. IB achieves low-latency and high-bandwidth data transmission through a dedicated physical layer and protocol stack.
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RDMA : It is a data transfer model that allows a host to directly access the memory of a remote host without CPU intervention. RDMA can significantly reduce data transfer latency and CPU overhead, thereby improving system performance.
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RoCE : RDMA over Converged Ethernet is a technology that extends RDMA to Ethernet. RoCE implements low-latency and high-bandwidth data transmission capabilities similar to InfiniBand by running the RDMA protocol stack on Ethernet.
Therefore, the relationship can be summarized as follows:
Ethernet is a basic network technology that provides support for the physical layer and data link layer of data transmission. TCP is a transport layer protocol working on top of IP network, providing reliable data transmission.
IB is a dedicated interconnect technology that provides low latency and high bandwidth data transmission capabilities. RDMA is a data transfer model used in technologies such as IB and RoCE that allows a host to directly access the memory of a remote host.
RoCE extends RDMA to Ethernet, so that RoCE-capable devices can realize low-latency and high-bandwidth data transmission on Ethernet. Therefore, RoCE can be regarded as one of the implementations of RDMA on Ethernet.
To sum up, there is a close relationship among RDMA, RoCE, IB, TCP, and Ethernet, involving different levels of network technologies and protocols to meet the needs of high-performance computing and data center networks.
