Internet network flows take mysterious ways. Well, not really, but it is difficult and there are szenarios where carriers would be different for inbound/outboun

Internet network flows take mysterious ways. Well, not really, but it is difficult and there are szenarios where carriers would be different for inbound/outbound traffic to a certain destination. Thus, I don't think the premise that routers should know if the source of a packet is valid really holds true.