Jumbo frames support

Network Administration Guide for Hitachi NAS Platform

Part Number

All file serving interfaces of a server support jumbo frames. Jumbo frames enable transmission of Ethernet frames with a payload larger than 1500 bytes, and these frames co-exist with standard frames on an Ethernet network.

All file serving interfaces receive jumbo frames unconditionally, without any configuration changes. It is possible to configure a file serving interface to transmit jumbo frames by specifying an MTU size of between 1,501 and 9,600 bytes.

To use jumbo frame transmission, configure the following settings:

  • IP MTU for off-subnet transmits - bytes
  • Other Protocol MTU
Networking equipment that lacks the jumbo frames extension can drop jumbo frames and record an oversize packet error. Before configuring jumbo frame transmission, verify that all network equipment along the route (and at each end point) supports jumbo frames. If you enable jumbo frames and either network equipment or clients on the subnet do not support jumbo frames, it is possible to experience a loss of communication with the server or cluster.

Successful IP data transmission using jumbo frames depends on the destination IP address or sub-network. The maximum MTU size for a destination IP address or sub-network is configured as an attribute in the IP routing table.

The IP MTU in use is the lowest of:

  • The interface IP MTU setting
  • Any IP MTU specified by the selected route
  • Any IP MTU specified by the MTU command

The recommended MTU size is 8972 bytes (to compensate for the IP and ICMP headers).