What is the Jumbo Frame Supported by Switches and Adapters?

Ethernet traffic moves in units called frames. The maximum size of frames is called the Maximum Transmission Unit (MTU). When a network device gets a frame larger than its MTU, the data is fragmented (broken into smaller frames) or dropped. Historically, Ethernet has a maximum frame size of 1500 bytes, so most devices use 1500 as their default MTU. An Ethernet packet larger than 1500 bytes is called a Jumbo Frame. In NETGEAR products, this feature is disabled by default.

An Ethernet frame uses a fixed-size header. Since the header contains no user data, it's overhead. It is more efficient to transmit a larger frame — the overhead-to-data ratio is better.

The performance problem arises when the MTU of one device is different than another. Indeed, casual changes to MTU to "optimize performance" are likely to have the opposite effect. See MTU, Partial Loss of Internet Connection, and Performance for an explanation of MTU problems — before considering the effects of Jumbo Frames. Also note that Jumbo Frames only help LAN performance, traffic leaving your network to the Internet is limited to packets of 1500 bytes.

With Jumbo Frames, much larger frames than the Ethernet standard of 1500 bytes are supported. If most of your local network devices and applications can be configured for the same Jumbo Frame size, your network may benefit from large packets, little fragmentation, and little overhead. However, if there are many applications and devices on your network that already limit frames to less than 1500 bytes, Jumbo Frames might decrease your performance slightly.

NETGEAR products supporting Jumbo Frames

Jumbo Frame Configuration

NETGEAR adapters supporting jumbo frames are configured under Windows network connection properties:

NETGEAR Managed Switches are configured under the physical port’s properties. From the CLI:

(FSM7326P) >en
Password:

(FSM7326P) #config

(FSM7326P) (Config)#interface 0/5

(FSM7326P) (Interface 0/5)#mtu 9216

If using the Web GUI:

NETGEAR Managed Switches are configured through the Web GUI: Switch > Advanced > Jumbo Frame.

N101539.asp Aug. 30, 2005