I read something earlier that tripped me up, wondering how I could be wrong. It says here:
http://www.juniper.net/documentation/en_US/junos12.1/topics/concept/layer-2-lacp-security-understanding.html
"You must enable LACP when you configure a LAG."
That what was caught my eye and I read a bit more and it seems to quite definitively state that you just can not have a working LAG without LACP.
"When LACP is not enabled, a local LAG might attempt to transmit packets to a remote single interface, which causes the communication to fail. When LACP is enabled, a local LAG cannot transmit packets unless a LAG with LACP is also configured on the remote end of the link."
That got my hopes up. It doesn't work any other way! I thought to myself that I must have been expressly enabling a service that would be up and on and running anyway. You see, I have a couple LAGs that aren't running LACP and it's irked me but it's just-production-enough gear to leave it alone if it's working. So I double checked it and no dice. I've got 121589960198211 packets, zero errors, and a LAG that drops to zero if it loses a link, as no, there's no lacp subsystem running.
So I think the docs are wrong. Or I read it wrong possibly because that page read a bit SRX-ish as it listed a few models at one point, but if so I think it could be a bit more clear about the "suicide mode" LAG I'm running, in production, without LACP. No sane or right minded person would choose it, I agree, but still.
I'm also posting this here in hopes that the person who configured this sees this, and he stops by here often and I can think of no more perfect thank you note.
--tc