Sorry for my mis-wording.
I meant "I HAPPEN to use a TB-2-Gig adapter, which by itself SELF-ADJUST the MTU to match the one set on the switch".
I regard to this as a behaviour, not as a "feature" ;-).
But since I have a Macbook air, my only two options are either the "no-more-than-MTU1500" usb2ethernet, or
the "jumbo-capable" TB2Gig.
And the latter behaves just as outlined above, and this could be what happened to you.
As Jason outlined (and I agree) this is not related to Thunderbolt itself, but could explain why "it works for somebody, and not for somebody else": it depends on different HW, not necessarily Thunderbolt-based, and how such HW setup manages MTU.
For sure the bridging issue in adding the was due to the MTU mismatch between "en" and "tap".
@Jason,
Since my early networking days I was taught "MTU mismatch is bad", and I luckily discovered that.
Maybe this week I can work on more on my breakout switch setup (which happens to be, due mostly to space and "my wife would kill me if I make a mess of cables and devices" constrains, my only option, see below), and get back to you.
OT: A note on "HW" setup: my current rack is a plain Ikea "LACK" in the "on castors" version.
If you want to install such a piece of furniture, please
carefully check airflow of your devices before proceeding:
- usually 3560 and 3750 with Fastethernet have side-to-side airflow, and you should either choose a different "rack" (e.g. the original Lack table), or keep the switches turned on just when you need them (I'd suggest no more than 3-4 hours a day). This is my case.
- usually 3560 and 3750 with Gigabit ethernet have front-to-back airflow and the furniture pictured would fit pretty well.
Further ideas on
http://lackrack.org