rem: PPPInterface::EncapsulatorFor(uint16 protocol, PPPEncapsulator start = NULL) const
add: PPPInterface::EncapsulatorFor(uint16 protocol, PPPEncapsulator *start = NULL) const
context: PPPInterface::EncapsulatorFor(uint16 protocol,	PPPEncapsulator start = NULL) const{	PPPEncapsulator *current = start ? start : fFirstEncapsulator;		for(; current; current = current->Next())		if(current->Protocol() == protocol)			return current;		return current;}