Spark plugs having a center electrode and surrounding ground electrode configurations that allow the spark to selectively fire across the path of least resistance are disclosed. In particular, the VPLS multicast instances transport layer two multicast traffic, such as Ethernet packets, between customer networks via the public network. The lower receiver assembly is capable of having an ammunition magazine attached thereto for communicating ammunition from the ammunition magazine to the upper receiver assembly. When the comparison to the threshold value is positive, the three symbol pairs are the last six symbols in the predetermined sequence.