xDSL n Dial up connection ??? help

[Lowell Gilbert]

MoonblueZ <moonbluez at gmail.com> writes:

>          ----------         -----------
>          |  ISP 1 |     |  ISP 2  |
>          ----------         -----------
>              |                    |
>  (DHCP) |                    | (DHCP)
>              |                    |
>             -----               -----
> Dial up -->  |   |               |   |  <-- xDSL
>             -----               -----
>                \               /
>                ----------------
>                |   router     |
>                ----------------
>                       |
>                       |
>               --------------------
>
> I have some problem here, about how to setting freebsd router which have two
> link like topology above. i want the router have automatically detected if
> xDSL link has down n swicth the link to dial up automatically. even so was
> the reverse if link xDSL has up n dial up is disconnect automatically..

Aside from detecting the status of the DSL link, ppp(8) can handle
everything you need.  However, figuring out when the link goes down
can be tricky; among other things, the techniques available depend on
how you interface to the DSL line.  You may need some kind of
heartbeat -- in the worst case, you might need to set one up yourself
using a ping of some upstream router.

Good luck.
-- 
Lowell Gilbert, embedded/networking software engineer, Boston area
		http://be-well.ilk.org/~lowell/