Boogie Bumper

It's now officially known to me: It's not possible to terminate a pseudowire on a router subinterface. That is, at least - on a 7204VXR running advip 124-20.
<edit>Actually, it is, as I explain here.</edit>
Should someone be unfortunate enough to try this, you will encounter the following Optional Messages while watching 'debug vpdn l2x errors'. Best of all, they'll occur in a seemingly random order:

L2TP tnl 0219F:0000A30C: "No config found for remote peer R2, local/remote address,"
L2TP tnl 020F6:0000A3CE: "No application/session timer expired"
L2TP 00005:020F7:0000631C: "No disconnect reason given"
L2TP 00005:020F7:0000631D: "Payload type mismatch"

You may also find your tunnel is sitting in an Est-No-User or No-Sessions-Left state.
If you see this going on, swing that xconnect over to a physical interface and BAM! Instant tunnel, quicker than you can say undebug all.
Of note, you CAN also terminate them on a vlan interface, and in turn terminate that vlan onto an access switchport. On an NM-16ESW or something for example.

Obviously, I didn't get quite as far in my testing as I had hoped having just isolated the cause for those not-so-helpful errors just now.

Also, today fscking sucked.

Huh. My kitty seems to have decided that it's petting time. I'd best do something about it.

<edit>Holy typo's batman. Fixed.</edit>