Jumbo frame support

Ethernet traffic moves in units called frames. The maximum size of frames is called the Maximum Transmission Unit (MTU). When a network device receives a frame larger than its MTU, the data is either fragmented or dropped. Historically, Ethernet has a maximum frame size of 1500 bytes, so most devices use 1500 as their default MTU.

Jumbo frames are Ethernet frames with more than 1,500 bytes MTU. Conventionally, jumbo frames can carry up to 10200 bytes MTU. FastIron devices support Layer 2 jumbo frames on 10/100, 100/100/1000, and 10GbE ports.

ICX 7xxx series devices support Layer 2 jumbo frames on 10/100, 100/100/1000, 40GbE and 10GbE ports. Conventionally, jumbo frames can carry up to 9,000 bytes MTU. In cut-through mode, in jumbo mode, the MTU is 10200 which uses 20 buffers. In non-jumbo mode MTU is 1522 which uses 3 buffers. Support for jumbo frames can be enabled using the jumbo command.