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Jumbo Frames

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Jumbo frames carry more data per packet, reducing packet count, CPU load, and transmission time in high-throughput scenarios such as data centers and HPC.

What is a jumbo frame?

Jumbo frames are Ethernet frames each with more than 1,500 bytes of payload, the limit set by the IEEE 802.3 standard. Alibaba Cloud instance families support Ethernet frames of up to 8,500 bytes.

Supported instance families

The following instance families support jumbo frames.

Instance families that support jumbo frames

For network metrics of instance families, see Instance family.

Jumbo frames are supported by default on g8i, c8i, r8i, c8ine, g8ine, and 9th-generation and later instances.

You can also call DescribeInstanceTypes to check whether an instance type supports jumbo frames. If JumboFrameSupport is true, the instance type supports jumbo frames.

Network performance benefits

  • Increased network throughput: Larger packets transmit more data per frame, reducing the total packet count and increasing throughput.

  • Reduced CPU load: Fewer frames mean fewer network interrupts and reassemblies, freeing CPU resources.

  • Reduced transmission time: Fewer frames lower per-packet overhead, benefiting high-bandwidth applications such as HPC, big data transmission, and storage area networks (SANs).

  • Improved bulk data efficiency: Applications that transmit large amounts of continuous data, such as database backup, large-scale file transfers, and video streaming services, gain higher speed with jumbo frames.

Use cases

Jumbo frames improve network performance for data-intensive cloud workloads, including:

  • Data center internal communication: Jumbo frames accelerate server-to-server data transmission for big data analytics, database synchronization, and distributed computing.

  • SAN: Jumbo frames reduce transmission overhead between servers and storage devices, improving data backup and restoration efficiency.

  • Virtual machine (VM) migration: Jumbo frames reduce network transmission time when migrating VMs between physical servers.

  • HPC: Jumbo frames increase data transmission rates for scientific computing and engineering simulations.

  • Video streaming and multimedia: Jumbo frames improve transmission efficiency for large video and multimedia transfers.

Jumbo frames and MTU

The maximum transmission unit (MTU) is the largest packet size that can traverse a connection without fragmentation. MTU includes the IP header and payload but excludes the Ethernet header. See Maximum transmission unit (MTU).

Jumbo frames are data frames transmitted on a network interface whose MTU exceeds the standard 1,500 bytes. When you enable jumbo frames for an ECS instance, the MTU of its network interfaces is automatically set to 8,500 bytes.

Usage notes

Jumbo frames improve performance in specific scenarios but may cause incompatibility or increased latency. Test and plan before enabling jumbo frames.

  • Device compatibility: Ensure all network devices, including switches, routers, and NICs, support jumbo frames. The MTU on all devices must be greater than or equal to the jumbo frame size. Otherwise, packets may be dropped or fragmented, degrading network performance. See the How the MTU affects network performance section in the "MTU" topic.

  • Protocol support: Ensure upper-layer protocols, such as TCP/IP, support jumbo frames. For example, adjust the TCP maximum segment size (MSS) to prevent unnecessary data fragmentation. See Maximum transmission unit (MTU).

    Important

    In non-TCP scenarios (such as UDP or ICMP), jumbo frames may not be fully utilized if no protocol or application layer optimizes for them. This may cause packet loss or application errors.

  • Probability of latency increase: On low-bandwidth links, large packets occupy the line longer and may block other packets, increasing latency.

  • Limits on cloud services: Jumbo frame transmission is limited by the MTUs supported by cloud services. See the MTU limits in practice section of the "MTU" topic.

    Connectivity or performance issues may occur in the following scenarios:

    • When UDP or ICMP jumbo frames access ECS instances or hosts associated with Server Load Balancer (SLB) instances, SLB may not forward fragmented packets as expected and may drop them, causing connectivity issues.

    • When UDP or ICMP jumbo frames traverse MTU-mismatched paths, packets may be fragmented, degrading network performance.

Enable or disable the Jumbo Frames feature

Enable or disable jumbo frames for an ECS instance by using one of the following methods.

Important

If you manually change the MTU of the network interfaces (not recommended) and also enable or disable jumbo frames, the manually specified MTU takes precedence.

Enable or disable the Jumbo Frames feature when you create an instance

On the ECS instance buy page, select or deselect Enable Jumbo Frames when you choose an instance type that supports jumbo frames.

image

The feature takes effect after the instance is created and started.

Modify jumbo frames configurations

After you create an ECS instance, enable or disable jumbo frames from the instance details page.

  1. Go to ECS console - Instances.

  2. In the upper-left corner of the page, select a region and resource group.地域

  3. Find the target instance and click its ID. In the upper-right corner, click All Actions and choose Network and Security Group > Modify Jumbo Frames Configurations.

  4. In the Modify Jumbo Frames Configurations dialog box, enable or disable jumbo frames.

    jumbo.png

After you click OK, configure the operating system for the changes to take effect.

Enable or disable the Jumbo Frames feature by calling an API operation

Call the ModifyInstanceAttribute operation and set the EnableJumboFrame parameter. Then, configure the operating system for the jumbo frames configurations to take effect.

Configure the operating system for the jumbo frames configurations to take effect

If you modify the jumbo frame configurations after instance creation or via API, restart the network service or network interface for the changes to take effect. The steps vary by operating system.

Windows instance

Restart the instance. After you enable or disable jumbo frames on a Windows instance, restart the operating system for the configuration to take effect.

Linux instance

  1. Connect to a Linux instance.

    See Connect to a Linux instance by using a password or a key.

  2. Restart the network service for the configuration to take effect.

    Note

    If DHCP is enabled for a network interface, run sudo dhclient to obtain the latest MTU. For example, sudo dhclient eth0 dynamically obtains the network configurations of the primary NIC, including the MTU. 

    sudo systemctl restart NetworkManager

    The restart command varies by Linux distribution and network service manager. The following table lists common commands.

    Operating system

    Restart command

    • Alibaba Cloud Linux 2

    • CentOS 7

    • Red Hat 7

    • Anolis 7

    • SUSE Linux 11/12/15

    • openSUSE 15/42

    sudo service network restart

    or sudo systemctl restart network

    • CentOS 6

    • Red Hat 6

    sudo service network restart

    • Alibaba Cloud Linux 3

    • CentOS 8

    • Red Hat 8

    • Anolis 8

    • Fedora 33/34/35

    sudo systemctl restart NetworkManager or sudo reboot

    • Ubuntu 18/20/22

    • Debian 12

    sudo netplan apply

    • Ubuntu 14/16

    • Debian 8/9/10/11

    sudo systemctl restart networking or sudo reboot

Best practices

Follow these best practices when using jumbo frames for data-intensive workloads such as SANs, big data transmission, and HPC:

  • Evaluate requirements. Jumbo frames benefit applications that transmit large data chunks, such as big data analytics, backup and restoration, and HPC. If your network mainly carries small packets, jumbo frames may not help. See Use cases.

  • Evaluate device and protocol support.

    • Device consistency: Ensure all network devices on the path (switches, routers, servers, NICs) support jumbo frames and use the same MTU. Inconsistent MTU settings cause unexpected fragmentation or packet drops.

    • Upper-layer protocol compatibility: Adjust upper-layer protocol configurations (such as TCP window size) to support jumbo frames for optimal performance.

  • Testing and verification: Before enabling jumbo frames in production, perform comprehensive testing in an isolated environment, including throughput, latency, and fault recovery tests. See Network performance testing.

  • Consistent MTU setting: Set the same MTU on all devices in the network. Inconsistent MTU values cause packet fragmentation or loss.

    Enable or disable the Jumbo Frames feature: Use Alibaba Cloud-provided methods to enable or disable jumbo frames instead of manually changing the MTU in the operating system. See Enable or disable the Jumbo Frames feature.

  • Monitoring and adjustment: Continuously monitor network performance after enabling jumbo frames. Some older devices may not handle jumbo frames correctly, or misconfigurations may cause issues. Adjust network configurations based on monitoring results.

FAQ

  1. Problem description: When you use jumbo frames for UDP or ICMP traffic, instance performance drops significantly.

    Solution: Check whether packets are fragmented and disable jumbo frames if needed. See Enable or disable the Jumbo Frames feature.

  2. Problem description: When you access cloud services such as OSS and ApsaraDB for RDS over UDP or ICMP from a jumbo-frame-enabled instance, network connections fail.

    Cause: Traffic flows through SLB instances that cannot forward packet fragments, causing connection failures.

    Solution: Set the MTU to 1,500 bytes or less to prevent packet fragmentation.

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