IBM Cloud Docs
Enabling Jumbo Frames

Enabling Jumbo Frames

A jumbo frame is an Ethernet frame with a payload greater than the standard maximum transmission unit (MTU) of 1,500 bytes. Jumbo frames are used on local area networks that support at least 1 Gbps and can be as large as 9,000 bytes.

Jumbo frames need to be configured the same on the entire network path: source device > switch > router > switch > destination device. If the entire chain isn't set the same, it defaults to the lowest setting along the chain. IBM Cloud® has network devices set to 9,000 currently. For best performance, all customer devices need to be set to the same 9,000 value.

Enabling Jumbo Frames

  1. Edit the network configuration file for eth0 interface.

    • CentOS, RHEL, Fedora users edit /etc/sysconfig/network-scripts/ifcfg-eth0.
      # vi /etc/sysconfig/network-scripts/ifcfg-eth0
    • Debian and Ubuntu users edit /etc/network/interfaces.

  2. Append the following configuration directive, which specifies the size of the frame in bytes.

    • CentOS, RHEL, Fedora
      MTU 9000
    • Debian and Ubuntu
      MTU=9000

  3. Close and save the file. Restart the Interface eth0.

    # /etc/init.d/networking restart

    This action causes a brief loss of network connectivity.