Relies on pathAnimator.js and d3.js

animate-element-snap-svg.js

// requires snap-svg.js
function animateOverPath(el, path, duration, callback) {
	len = path.getTotalLength();
	Snap.animate(0, len, function (l) {
		var dot = path.getPointAtLength(l);
		x = dot.x - el.getBBox().width/2;
		y = dot.y - el.getBBox().height/2;
		el.attr({
			transform: "t" + [x,y] + "r" + (dot.alpha - 180)
		});
	}, duration, callback);
}

animate-packet.js

// requires d3.js and pathAnimator.js
function animatePacket (path, packet, speedz, finishCallback){
	    var pathAnimator = new PathAnimator(path);
	    pathAnimator.start( speedz, step, false, 0 /* startoffset */, finish);
	   
		function step(point, angle) {  // do something every "frame" with: point.x, point.y & angle
			packet.attr("x", point.x - packet.attr("width")/2).attr("y", point.y - packet.attr("height")/2);
		}
		
		function finish() {
			finishCallback(packet);
		}
	}
	
	// usage
	
		var originalPacket = self.networkDiagram.select("#packetSelector").node();
			var packet = self.networkDiagram.select("#layer2").select(function() { return this.appendChild(originalPacket.cloneNode(true)); })
			var srcPath = self.networkDiagram.select("#path-selector").attr("d");

			animatePacket(srcPath, packet, 1,  function(pckt){
			  console.log("done");
			});