On Thu, May 28, 2015 at 3:13 PM, Phillip Hallam-Baker wrote:

Fill is very expensive at the network layer but (almost) trivially cheap at the link layer. The cost comes in having to think about how much data is disclosed in the link layer framing. This is not necessarily a performance issue but can certainly be an architectural constraint.

What example do you mean "how much data is disclosed in the link layer framing"? I thought it was decided months back that encryption would be needed to prevent disclosure to anyone other than the two link partners. (And that encrypting the hardware link layer is trivially cheap in silicon.)