How to bridge 2 LANs, each with own DSL router

Sounds like a perfect scenario to use two firewall devices with a VPN between the two LAN's.  You could use two LinkSys BEFVP41's for example with a VPN tunnel configured between the two.  That would allow users regular internet access and also allow communication between the two LAN's over the VPN.

what mask do you have for each subnet?
if it is 255.0.0.0 then you will have to change it b/c they are both on the same subnet
if it is 255.255.255.0 then you are ok b/c each has their own subnet.

are the two lans in the same or different sites?
if they are in different sites you will have to get a dedicated circuit between them (or setup a VPN)
if they are in the same site, you simply need to setup a router between the two and setup routing properly.

As i read in the post, the two networks are colocated in a same office and have a 255.255.255.0 mask.  

Then as mikeleerbrla said, add a router between the two subnets.  On each routers  add proper static routes or enable dynamic routing protocol on all routers.

DSL LIne                                                   DSL LIne
    |                                                               |
    |                                                               |
 ROUTER-A                                             ROUTER-B
IP:10.0.0.1                                              IP:10.0.1.1
route 0.0.0.0  gw WANIP                          route 0.0.0.0  gw WANIP
route 10.0.1.0 gw 10.0.0.2                       route 10.0.0.0 gw 10.0.1.2
   |           |                                                     |                     |
LAN -1      |                                                     |                   LAN-2
                |                                                    |
        [L1 IP: 10.0.0.2]-- ROUTER-C---[L2 IP: 10.0.1.2]
       

Distance between these 2 routers is about 50 m. But they are located in one building and it will be easiest and cheapest to connect them wirelessly (even thought most users are connected wirelessly).

Danny_Larouche:

I just looked at Speedtouch's web administration page and under IP ROUTING there is a table with following columns:
DESTINATION, GATEWAY, INTERFACE and METRIC filled with about 10 rows with different adresses.

For ROUTER A and B what to set as DESTINATION and GATEWAY?

How to configure ROUTER C?
Should I use this router http://www.zyxel.com/product/model.php?indexcate=1076902407&indexFlagvalue=1085450343 ??

No  it will not work.  Access point cannot act as client and connect to each other until they have  a "wireless bridge" mode.  It would cause a lot of latency on the network to use such design.  It could be much more efficient to use wired equipment.

The routes for router A and B has been provided in my first posts.  

Assuming the router(A) attached the LAN1 have IP:10.0.0.1
route for LAN2 is: destination=10.0.1.0 mask= 255.255.255.0 gateway= 10.0.0.2 (IP of routerC)

Assuming the router(B) attached the LAN2 have IP:10.0.1.1
route for LAN1 is: destination=10.0.0.0 mask=255.255.255.0 gateway= 10.0.1.2  (IP of routerC)

Ok, thanks, but:

Can I use standard 5 or 8 port switch or standard broadband router with 4xLAN and 1xWAN as ROUTER C ?

And how to configure it to work as ROUTER C as you described. (what mode to use - ROUTER C will have 2 IPs ?)

Ok, thanks.