Hypervisor Ethernet Limits

From the Advanced POWER Virtualization on IBM System p5 Redbook:

The POWER Hypervisor’s virtual Ethernet switch can support virtual Ethernet frames of up to 65408 bytes size, which is much larger than what physical switches support: 1522 bytes is standard and 9000 bytes are supported with Gigabit Ethernet Jumbo Frames. Thus, with the POWER Hypervisor’s virtual Ethernet, you can increase TCP/IP’s MTU size to 65394 (= 65408 - 14 for the header, no CRC) in the non-VLAN-case and to 65390 (= 65408 - 14 - 4 for the VLAN, again no CRC) if you use VLAN. Increasing the MTU size is good for performance because it reduces processing due to headers and reduces the number of interrupts that the device driver has to react on.

See Also

• Advanced POWER Virtualization on IBM System p5 Redbook.
• Virtual Networking on AIX 5L Whitepaper archived on scribd.