Cisco IOS XE 16.1.1 allows remote attackers to cause a denial of service (device reload) via a packet with the 00-00-00-00-00-00 source MAC address, aka Bug ID CSCux48405.
http://www.securitytracker.com/id/1034514
http://www.securityfocus.com/bid/79654
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-2015-1221-iosxe