Re: Asymmetrical routing opinions/debate

There's the somewhat trivial efficiency that if you're willing to accept asymmetric routing, you spend a lot less time tweaking your networks than if you insist on symmetry, and the more significant issue that the network will usually be more resilient and reliable (though slightly less predictable) if you're not tweaking it. Essentially, if you don't control all the parts of the network that your packet uses, you're not able to directly set optimization parameters, so what you're doing to get symmetry is throwing lots of hints at the network and hoping some will stick, and the parts of the network that happen to cooperate with you may not be the best ones that are otherwise available.