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I have two stores in two different sides of the same street, Each one has an ADSL connection with a wireless router and a different IP address.

So I have two different wireless networks connected to the Internet separately.

I want to share these networks so that when one ADSL router is disconnected from the Internet it will connect to the other network wirelessly to keep the connection.

I want the networks to be connected 24/7 in both the stores, and in case of ADSL problems in one of the networks, the other network will back it up.

I can't connect a cable between the stores, because there is a road between them.

How can I configure the routers to share my networks?

EDIT: The reason I'm asking this question:

I have two CCTV systems with DVRs, one in each store. Each is connected to its own router, and I want them both to be online even when one internet connection is lost.

This way I can always connect to the CCTV of both stores using my phone or home computer and know that everything is OK...

The solution of creating one wireless network seems good, but I need the DVRs to work on both networks, so I need the routers to connect to each other wirelessly (is that a word?).

I would also accept a solution involved with changing my hardware.

Thanks...

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1  
Well you can try it with two VPN-Routers and set a secondary gateway to the opposite Router. –  M.Meintjes Jul 31 '13 at 14:23
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You could put both routers on the same IP subnet, but just have each router use a different range for DHCP (say... 2-50 for the first one, and 100-150 for the second one). You could even use the same SSID, set one for channel 1, and the other for channel 6 or 11... and then just leave them alone. Devices within range will connected to the strongest, and if one goes down, devices will just use the one that is up. –  Bon Gart Jul 31 '13 at 17:13
    
@Bon, can I connect the router to the other router's network? –  Shahar Aug 13 '13 at 9:54
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Since both routers would be using the same SSID and IP Subnet, it would essentially be a single network. You ask if you can connect the "router" to the "other router's" network... that all depends on if you have a router that can wirelessly connect to another source (aka a wireless access point). However, that would require altering the configuration when you wanted to set it up like that. –  Bon Gart Aug 13 '13 at 16:18
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→ Shahar: no you don't need your 2 routers to connect to each others wirelessly. Your DHCP scheme will depend if they do "see" each other. –  daniel Azuelos Aug 19 '13 at 18:46

3 Answers 3

up vote 2 down vote accepted
+50

Sounds like you want a routing based on availablilty of the uplink to the provider.

(The availability of the WiFi is already handled by normal procedures. If one goes down and your client knows both WiFis it just connects to a different one.)

What you want is:

Two Internet connections <-INTERNAL-CONNECTION-> Router <-INTERNAL-CONNECTION #2-> Clients

The router can determine if an internet connection is up and offer a secondary backup. The internal connections can be everything.

Example:

DSL#1 <-> Cable <-> SingleAndOnlyRouter <-> CableOrWiFi <-> ClientInHouse#1
DSL#2 <-> WiFi <-> SingleAndOnlyRouter <-> WiFi <-> ClientInHouse#2

Of course there are other possibilities, but this would give you the flexibility you need.

Probably there are off the shelve components to do this (can't help you here), or you can setup your own "routing" server (Linux/BSD/Unix or Windows).

Your DVR would be a one possibilitity of a client. Like this:

DSL#1 <-> Cable <-> SingleAndOnlyRouter <-> CableOrWiFi <-> DVR#1
DSL#2 <-> WiFi <-> SingleAndOnlyRouter <-> WiFi <-> DVR#2

Both use the same internal network in this example (although the setup could even be improved there, but seems like a little overkill). The router will recognize when one DSL line is down and alternatively use the second.

It is also possible to use both in parallel so automatically a lost uplink will be transferred to second uplink (Example).

I did a quick research for components offering the routing possibility out of the box (not setting up your own server): Cisco/Linksys offers it.

harrymc offered a cool link for this in his answer:
http://www.smallnetbuilder.com/finders/router/products

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Could you explain where I should connect the DVRs to? –  Shahar Aug 20 '13 at 5:59
    
DVR would be a possible client. –  StampedeXV Aug 20 '13 at 6:34
    
I need both the DVRs to be online 24/7, by connecting to their router with a wire or connecting to the other router wirelessly in case their router is disconnected –  Shahar Aug 20 '13 at 7:01
    
In my scenario you would only have one router which would handle failing uplinks (i.e. managing two uplinks - able to handle one failing). I did not consider router defects. For that there are also possibilities, but of course it gets more difficult. –  StampedeXV Aug 20 '13 at 7:19
    
I want to give you the Bounty, but I still don't have an answer... –  Shahar Aug 20 '13 at 7:53

You could use a multi-WAN router, one that does automatic fail-over.

To get some idea as regarding candidate routers, you can use the Router Finder, and click the WAN Ports link twice in the Features section to sort by descending number of ports.

This finder does not list Draytek routers, and I have heard good opinions regarding fail-over for the Draytek Vigor 2920. Also for Cisco RV0XX routers.

For a router that supports DD-WRT, this firmware can also do Dual WAN with failover, although some script-writing is required.

Fail-over is not instantaneous and may take a few seconds, depending on the test-frequency built-into the router. When the switch happens, any existing connection will be disconnected since the router will shift from one IP address to another. If you change ISP, this can be even slower.

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Check that your 2 wireless routers are wirelessly accessibles from the other side of your street.

If this wireless point is OK just configure your 2 wireless routers:

  1. So as to broadcast the same wireless network name (SSID).
  2. So as to use separated channels. Most notably if you want to accept 802.11b or 802.11g clients, take care to choose 2 channels separated by 3 (example: 1, 5).
  3. As DHCP servers on the wireless side (only) and so as:
    • to use the same IP addresses range if your 2 routers see each other (on the wireless side, correct DHCP servers will manage this without any other abnormal configuration), for example : 192.168.0.0/24 or 192.168.0.0 → 192.168.0.255),
    • to use separated IP addresses ranges if your 2 routers won't see each other, for example : 192.168.0.0/24 (192.168.0.0 → 192.168.0.255) & 192.168.1.0/24 (192.168.1.0 → 192.168.1.255).

Your clients will switch from one router to the other:

  1. If one of your routers fails.
  2. If there are too much interferences to reach one of them.
  3. If one of them is overloaded with wireless clients.
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Could you give more information on how the DVRs will work on the wireless network? –  Shahar Aug 20 '13 at 5:55
    
If only internet fails w/o wireless failing one DVR would not be reachable though. –  StampedeXV Aug 20 '13 at 6:33
    
→ StampedeXV: right. This solution does only work in case of one of the ISP failing if they see each other wirelessly. In this case, the ICMP redirects will permit the traffic redirect from failed router toward sane router. If they don't, then my solution is a dead end, and there is none without adding an intermediate wireless repeater to connect the 2 wireless routers across the street. And I'm convinced this is a much too complicated setup regarding the original need. –  daniel Azuelos Aug 21 '13 at 14:18

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