[LARTC] Traffic shaping over two different lines

["Jan Gerritsen" <artur@gmx.net>]

Hi all,

I want to connect my LAN to the Internet over two different Connections. One is a static E1 (2Mbit) connection with a permanent IP, the other one is a so called DSL-Light connection (ADSL with 64kbit up and 384kbit downstream) with a dynamic IP. The reason is that I have to pay the traffic on the E1 and the DSL is flat fee. So of course I want to push as mush as traffic over the DSL line.
                 ________
            E1  |        | Ethernet
 Internet <---->| Router |<---------> LAN
          <---->|        |
           DSL  |________|

What I want to do is something like the following:

Basic model:
Because the upstream from the DSL connection is really to slow, I want to use the E1 for uplink and the DSL as downlink. (Can I do this by Masquerading with the IP of the DSL-Line and sending over the E1, so the Answer comes back over the DSL-Line?)

Exemptions:
- Some services, like SMTP, should always use the DSL-Line as uplink.
- Some services, like HTTP or SSH, should use the E1-Line as downlink.
- And my last wish, if the DSL-Uplink is not in use, this link should be used for sending data, until its bandwidth limit is reached, and only then traffic should be send over the E1, too.

I know its still some days till Christmas, but I don't want to shorten my wish list until you all tell me its not possible,.. but my problem is I don't know where to start.
I am good at using iptables/netfilter and already used tc for setting up some QoS rules for traffic shaping on different services,.. but I didn't do something like I want to do now.

So I want to ask you, to give some tips what techniques / services to use, to do something like this. How to set up the basic model and how to break it to complete my whish list ;).

Thanks,
Jan GerritsenÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿË\x01\x14™¨¥Šx%ŠË\x7f,\x04S\vùšŠYšŸ÷lõ¯ç–^[m§ÿÿ™¨¥™©ÿvÏZþy\x7f™¨¥™©ÿ–+-ŠwèþV«µÁÎY3ÿ†Ûiÿÿåj»\þŠà