This is the method I use to get the most out of 2 X 2mbps ADSL Connections. I'm using the built in Squid Proxy, and all proxy traffic uses both ADSL lines. All non http traffic just uses one ADSL line.
Let me tell you this is very fast Internet. I use a 1Gb RAM / Intel 3GHz CPU / 120Gb HDD just to have a big fast cache. I find the cache efficiency is 30 - 40%, so it's well worth having. I only use Winbox; here is what I did:
General Info
Router PC has 3 NIC's
1 for Local LAN IP 192.168.50.111 private address, 1 for each Internet Gateway with routable IP on each NIC.
Local LAN is NAT'd on the Gateway
Proxy running on port 8080
After adding the necessary IP Addresses to the NIC's, just add a route to one of the Gateways into the route list. This will be the catchall route.
Enable the Proxy as 'Transparent', and set the source IP to be 192.168.50.111 (the same as your LAN NIC)
In Firewall - NAT
Add a dst-nat rule to divert http requests to the Proxy:
Dst Address NOT 192.168.50.111
Protocol 6
Dst Port 80
In Interface LAN (your LAN NIC)
Action Redirect to Port 8080
There are another 2 rules needed in Firewall - NAT. These just NAT both Internet NICs onto your private LAN. They go like this:
Chain - srcnat
Out Interface - Gateway1
Action src-nat
To Addresses <IP of Gateway1 NIC>
To Ports 0-65535
Chain - srcnat
Out Interface - Gateway2
Action src-nat
To Addresses <IP of Gateway2 NIC>
To Ports 0-65535
Next, we move on to the Mangle, where we must mark traffic that has come from the Web Proxy and is destined for a Website. This mark will be called 'Proxy Traffic':
Chain - output
Src. Address - 192.168.50.111
Protocol - 6
Dst. Port - 80
Action - Mark Routing
New Routing Mark - Proxy Traffic
Now, we can move back to the Route List, and add an ECMP (dual ADSL lines in this case) Route. We can then define the traffic that will use this route as 'Proxy Traffic'.
Destination - 0.0.0.0
Gateway - <ADSL Gateway1; ADSL Gateway2>
Check Gateway - arp
Mark - Proxy Traffic
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For interesting stats about the RouterOS Proxy, I use the new Kraken Reports. This now works with v2.9 logfiles, and tells you good stuff like
Every site a user has been on, and what time
How much www traffic each user has downloaded
Cache hit rate per user and in total.
Kraken is currently donerware, and I'm nothing to do with them btw.
hope that makes sense,
Steve Head
TBI