networking network_error ai_generated true

Ethernet: jumbo frame size 9600 bytes exceeds interface MTU 1500 on eth0, packet dropped

ID: networking/ethernet-jumbo-frame-mtu-exceeded

Also available as: JSON · Markdown · 中文
76%Fix Rate
82%Confidence
1Evidence
2024-01-10First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
Linux kernel 6.1.0 active — — —
Cisco IOS 15.2(7)E active — — —
Mellanox ConnectX-5 firmware 16.32.1016 active — — —

Root Cause

A device attempted to send a jumbo frame larger than the interface MTU, causing the packet to be dropped at the data link layer without fragmentation.

generic

中文

设备试图发送大于接口MTU的巨型帧，导致数据包在数据链路层被丢弃而不进行分片。

Official Documentation

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-6500-series-switches/29805-175.html

Workarounds

  1. 95% success Increase the interface MTU to accommodate jumbo frames: `ip link set dev eth0 mtu 9000` on Linux, or `mtu 9000` in interface config on Cisco switches. 
    Increase the interface MTU to accommodate jumbo frames: `ip link set dev eth0 mtu 9000` on Linux, or `mtu 9000` in interface config on Cisco switches.
  2. 85% success Ensure all devices in the path support jumbo frames by checking with `ping -M do -s 8972 <destination>` (Linux) to test large packet delivery. 
    Ensure all devices in the path support jumbo frames by checking with `ping -M do -s 8972 <destination>` (Linux) to test large packet delivery.
  3. 80% success Segment the network so jumbo frames are only used in dedicated storage or backup VLANs with consistent MTU settings. 
    Segment the network so jumbo frames are only used in dedicated storage or backup VLANs with consistent MTU settings.

中文步骤

  1. Increase the interface MTU to accommodate jumbo frames: `ip link set dev eth0 mtu 9000` on Linux, or `mtu 9000` in interface config on Cisco switches.
  2. Ensure all devices in the path support jumbo frames by checking with `ping -M do -s 8972 <destination>` (Linux) to test large packet delivery.
  3. Segment the network so jumbo frames are only used in dedicated storage or backup VLANs with consistent MTU settings.

Dead Ends

Common approaches that don't work:

  1. 95% fail

    Jumbo frames are Layer 2 constructs; IP fragmentation applies to Layer 3 and cannot split an Ethernet frame.

  2. 70% fail

    Application buffers do not control frame size; the NIC driver segments data into MTU-sized frames.

  3. 90% fail

    An MTU of 0 is invalid and causes the interface to fail to transmit any packets.