Adding one additional packet of size 58B.
 - 6B destination mac
 - 6B source mac
 - 2B ethertype
 - 44B payload

As per the following documents, the DUT is supposed to provide padding to ensure that the data field is 46B in length.

* Ethernet: The definite guide. O'Reilly.  Page 51.
* http://docwiki.cisco.com/wiki/Ethernet_Technologies