The new Cisco IOS Firewall for Internet Protocol version 6 (IPv6) provides stateful inspection to both existing IPv4 and IPv6 traffic on a single interface for enhanced performance, along with better management of the IPv6 migration process.
Causes of Muscle contractions that are rare. The offical US government definition of a rare disease is one that affects 200,000 people or less. The following causes of Muscle contractions appear in the population at a rate of less than 200,000 people per year in the USA: 1  Alpers Syndrome-involuntary muscle contraction. 2  Fahr's Syndrome-athetosis. 3  Ramsay Hunt syndrome Type II-involuntary muscle contraction.
Leg Muscle Spasms. Muscle spasms in the legs are quite common and usually present themselves in the calves, just below the back of the knee. Pain during a muscle spasm can range from mild to severe, and can last up to 10 minutes. Poor circulation in the legs, alcohol consumption, high or low concentration of sodium or potassium, overexertion of muscles and some medication are among some of the reasons why leg muscle spasms occur.