Cisco Carrier Routing System 3.9.1 allows remote attackers to cause a denial of service (Metro subsystem crash) via a fragmented GRE packet, aka Bug ID CSCts14887.
https://exchange.xforce.ibmcloud.com/vulnerabilities/75341
http://www.securitytracker.com/id?1027006
http://www.cisco.com/cisco/software/release.html?mdfid=280777815&softwareid=280867577&release=3.9.1