The default MTU is 1500. To enable Jumbo Frames support, you
     can  configure  the  bge  driver by defining the default_mtu
     property via dladm(1M) or in driver.conf(4) to greater  than
     1500  bytes  (for  example: default_mtu=9000). Note that the
     largest jumbo size supported by bge is 9000 bytes. Addition-
     ally,  not  all  bge-derived devices currently support Jumbo
     Frames. The following devices  support Jumbo  Frames  up  to
     9KB:   BCM5700,  5701,  5702,  5703C,  5703S,  5704C, 5704S,
     5714C, 5714S, 5715C and 5715S. Other  devices  currently  do
     not support Jumbo Frames.