The data-link switching (DLSw) component in Cisco IOS 12.0 through 12.4 allows remote attackers to cause a denial of service (device restart or memory consumption) via crafted (1) UDP port 2067 or (2) IP protocol 91 packets.

More... (http://nvd.nist.gov/nvd.cfm?cvename=CVE-2008-1152)