8.5.3. Some SEA Attributes

Each SEA has a number of attributes, that can be set when it is created or, in some cases, can be changed later. The attributes can be listed using “vios help mksea“:

$ vios help mksea
vios [-h <hmc>] [-m <ms>] mksea [-M [-a]] [-v] <vios> <target_device> <ent> ... [<attribute> ...]


accounting : enable per-client accounting
adapter_reset : reset real adapter on HA takeover
ctl_chan : control channel adapter for SEA failover
fb_delay : delay before failback occurs (seconds)
ha_mode : high availability mode
jumbo_frames : enable Gigabit Ethernet Jumbo frames
large_receive : enable receive TCP segment aggregation
largesend : enable hardware transmit TCP resegmentation
link_time : time in seconds required for the link to be declared
healthy after a status change
lldpsvc : enable IEEE 802.1qbg services
noauto_failback : disable auto failback
pvid : PVID to use for the SEA device
pvid_adapter : default virtual adapter to use for untagged packets
real_adapter : physical adapter associated with the SEA
virt_adapters : list of virtual adapters associated with the SEA

Further attributes can be found in the IBM documentation, or they can also be easily displayed for a SEA using “vios lsattr“.

In the age of 100 Gb/s Ethernet, the attribute jumbo_frames is certainly one of the most important attributes. As a rule, jumbo frames should be used by specifying jumbo_frames=yes as an argument, when creating a SEA with “vios mksea“.

Many physical network cards offer hardware support for some TCP operations, which can be activated with large_receive=yes and largesend=1.
A detailed description of these attributes can be found in various IBM documents.