That's an interesting use case, with definite application, but I
wonder if it's really compelling in the case of the simple CPE
Router.
When CPE Routers are cascaded, the cascaded router is generally
directly connected to the upstream router, so that there would be no added
efficiencies from this.
Also, service providers that I talk to are quite
adamant about not wanting to see RAs coming at them from the WAN interfaces of
CPE Routers. I could easily envision some SPs disabling connections where they
see RAs. So CPE Routers that did this could potentially create a very bad user
experience, if there were Terms and Conditions (that the customer agreed to but
didn't read or necessarily understand) that said it was forbidden for them to
have their router send RAs.
I would rather if sending RAs out a WAN
interface were considered a function for medium/high end business or enterprise
routers, but not CPE routers. I think you will see CPE routers supplied by
service providers will not do RA (or any other route advertisement) to the
WAN.
Barbara