Jumbo frames

In short: Jumbo frames are Ethernet packets of up to about 9000 bytes instead of the usual 1500. They reduce overhead for large data volumes.

In more detail: Each packet has header data and costs the CPU work. Larger packets mean fewer packets for the same amount of data.

In Depth

• Use: Storage networks (iSCSI, NFS), backups and data-centre links between servers carrying large data streams.
• Gain: Fewer interruptions and less header data, slightly more throughput and less CPU load, typically a few percent up to 20 %.
• Condition: Every device along the path (network cards, switches, routers) must use the same MTU. A single device at 1500 causes lost or fragmented packets.
• Setting: ip link set eth0 mtu 9000. Test: ping -M do -s 8972 target.
• On the internet: Not usable, 1500 applies there. On a home LAN it brings hardly any advantage.
• Advice: Use only in closed, fully controlled networks and test thoroughly.

See also: ip command and ethtool