private void modifyLinkParser(String input){
			Scanner inputscanner = new Scanner(input);
			inputscanner.next(); //take away command
			
			Node source = getNodeFromName(inputscanner.next());
			Node dest = getNodeFromName(inputscanner.next());
			Link link = getLink(source, dest);
	
			while(inputscanner.hasNext()){
				String token = inputscanner.next();				
				if(token.charAt(0) =='u' || token.charAt(0)=='U'){
					System.out.println(link.getSourceNode().getName()+"-"+link.getDestNode().getName()+" is up.");
					link.setActive(true);
					link.setActivityChange(true);
				}
				
				else if(token.charAt(0)=='d' || token.charAt(0)=='D'){
					System.out.println(link.getSourceNode().getName()+"-"+link.getDestNode().getName()+" is down.");
					link.setActive(false);
					link.setActivityChange(true);
				}
				
				else{
					int cost  = Integer.parseInt(token);
					link.setCost(cost);
					link.setCostChange(true); //so routing algorithm in node class knows to update routing table
					System.out.println(link.getSourceNode().getName()+"-"+link.getDestNode().getName()+" now costs "+link.getCost());
				}
			}
			//update routing tables of cost and availability
			updateLinks();
			inputscanner.close();
		}