Multi-dog households can be hard when we have one high energy dog and one older dog. They can work really well though - teaching the younger one to be appropriate and bringing some lightness and fun into an older dog. 

We often think that we have to let the dogs work it out and teach each other, but the truth of the matter is that we are the ones who have to manage and teach here. Preventing the older dog from being bothered will protect their relationship. This means that you will have to give the younger dog a warning cue ("that's enough") as soon as you see that the older dog is not enjoying the interaction. If the behaviour stops, you verbally reinforce the younger dog and redirect them to an activity while protecting the older dog from being re-engaged with. If the behaviour does not stop with the warning cue, you give the time-out cue ("too bad") and gently remove them from the situation to protect the older dog.