User Manual

Rev 4.70
Mellanox Technologies
176
C.3 Basic Registry Keys
This group contains the registry keys that control the basic operations of the NIC
Value Name Default Value Description
*JumboPacket 1500 The maximum size of a frame (or a packet) that can be sent over
the wire. This is also known as the maximum transmission unit
(MTU). The MTU may have a significant impact on the network's
performance as a large packet can cause high latency. However, it
can also reduce the CPU utilization and improve the wire effi-
ciency. The standard Ethernet frame size is 1514 bytes, but Mella-
nox drivers support wide range of packet sizes.
The valid values are:
• Ethernet: 600 up to 9600
• IPoIB: 1500 up to 4092
Note: All the devices across the network (switches and routers)
should support the same frame size. Be aware that different net-
work devices calculate the frame size differently. Some devices
include the header, i.e. information in the frame size, while others
do not.
Mellanox adapters do not include Ethernet header information in
the frame size. (i.e when setting *JumboPacket to 1500, the actual
frame size is 1514).