Traceroute with Multiple Paths

[tsmarcyes]

Pretty straight forward question....L3 device with equal cost paths to destination.  Both next hops are equal distance in terms of AD and metric (think shared segment with 3 devices).  Traceroute will show both next hops when in the reply.  Now, how does the router determine the first probe to send to?  And how do you change this behavior? 

For example, traceroute 8.8.8.8 will send probe to both 10.1.1.1 and 10.1.1.2 (equal cost next hops).  Now, was 10.1.1.1 the first probe sent simply because its lower?  How do you change this behavior such that 10.1.1.2 will be sent the first probe first?

Reply....

1    - 10.1.1.1

        10.1.1.2

[Reza Sharifi]

Since they are equal cost, the router randomly pick one or the other.  So the router will load balance the traffic between the 2 next hops.  Now, this load balancing is not always 50/50.  It could be 40/60 or 70/30 and so on.  If you change the behavior by changing the metric or cost than that is not equal cost and so there is no load balancing, but rather active/stand-by.

HTH