How I support you all in this, I have a neighbour with 2 spaniels the owner when walking alway came past our yard with the two bitches. he would stop at the gate to look at Bell & Hovis whilst the spaniels barked agressively at them. (something they do to all dogs and humans). MY 2 would bark back, then he would walk away whilst I had to go outside and reprimand my dogs for barking. What makes it worse is that although a public right of way, the man has to go out of his way to use it.
What finally stopped him doing this was Bell and Hovis who escaped from the yard whilst I was carrying in shopping from the car. They heard his two spaniels barking and disappeared at a gallop in that direction. When I got there I was told that Bell had cleared a 3 foot gate to get into the garden and at the spaniels, the spaniels had disappeared inside the house.
There could have been a lot of trouble as a result but luckily the only outcome was that he keeps his dogs away from mine and he seems to be trying to control their aggression.
There seems to be a rule in this world that it is funny for small dogs to be aggressive towards large ones but wrong for a large dog to be provoked. It has just struck me that this rule translates well into human society and world politics, but I refuse to go there.
I feel that the best solution would perhaps be a three barks and you're out law, whereby large dog owners have the right on the third agressive bark of a small dog,to apply a boot to the dogs backside and launch it into next week!!

It might not be fair, reasonable or correct but by god it wouldn't half ease the stress of the encounter.
Andy Bell and Hovis