[c-nsp] Multilink PPP Over Multiple LNS(es)

[Dominic Ogbonna]

(a.) Let's say you have two LNS(es): Lns-1 and Lns-2
(b.) Let's say each builds its own transport L2TP tunnel back to the LAC(s),
perhaps via redundant circuits
(c.) Let's say the LAC(s) religiously round-robin between the two LNS(es)

In the above scenario, what would be the best practice for supporting
Multilink PPPOE / Bonded ADSL on the LNS?

I ask because, if you enable multi-link on both LNS(es), you obviously end
up with multilink bundles where the L2TP session is split between two L2TP
tunnels - one link authenticating to one LNS/tunnel, the other
authenticating  to a different LNS/tunnel, leading to all kinds of routing
and network weirdness, especially when one of the multilink member-links
drops. 

For LNS box, we are talking two Cisco 7206 with NPE-G2, so Multi-Chassis LNS
is not an option.

Thoughts on best practice?
Dominic