Solved 1 printer 2 networks with 2 different ISPs

Microsoft Windows xp professional w/sp2
September 16, 2015 at 00:36:05
Specs: Win 7 home, more than enough
Hi, here's the background:

I have two networks with two different ISPs. Since one is a reserve/a backup in case the other fails or goes down and I have to make a fast cable switch, they both have the same IP-range (192.168.50.xx). I have one network printer which is set to a fixed IP in both the networks (192.168.50.25). The networks are completely separate with two routers (and when I need, I can connect all my devices to either one).

Now however, for some reason - some comps are using the "reserve-network" and need to be able to use the printer. (I won't go into details about why things are as they are)...

I wonder: What will happen if I connect the printer to a (dumb) switch which is connected to BOTH the networks.... will there be any strange conflicts? (I'd rather not do any port programming, just wondering if I can do it like this).



See More: 1 printer 2 networks with 2 different ISPs

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✔ Best Answer
September 17, 2015 at 06:39:22
The dual WAN router is your best solution at this point. While it is an extra expense, it will handle the failover automatically which, once properly configured, will not require any further configuration by the admin.

In fact, unless you can set it up to notify you if your primary provider goes down (recommended as it allows you to contact them to ensure they are aware) you wouldn't even notice it had happened.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***



#1
September 16, 2015 at 00:43:36
Can we assume that all your computers have fixed IP addresses? If not, have you set the DHCP ranges on the two routers so that they don't overlap?

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#2
September 16, 2015 at 01:10:23
The two routers are set almost identically (since one is meant to be a stand-in for the other as a reserve). And no, the comps have not fixed IPs (but the other devices such as other printers and machines have).

What will happen if I connect the printer to the two networks do you think? A total melt-down? :)

message edited by nooner


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#3
September 16, 2015 at 01:23:02
You will get IP address conflicts as the two routers give out the same DHCP addresses to different computers. Near enough a total melt-down.

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Related Solutions

#4
September 16, 2015 at 02:04:30
So if I set static/fixed IPs to all connected devices (which hence are set identically in BOTH routers), it will work?

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#5
September 16, 2015 at 02:27:43
Yes. But you have to manually set the default gateway, which means that if you want to switch a computer from one network to the other you will need to adjust this parameter manually. Alternatively you could set up non-overlapping DHCP ranges on the two routers, but you then have no way of controlling which computer connects to which router. (I'm assuming that the routers have different IP addresses - if not you will have big problems.)

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#6
September 16, 2015 at 02:38:05
(The routers have exactly the same local IP and other settings, but not the same external IP [which has nothing to do with this]). All I want is to make three computers connected to LAN1 be able to use a printer connected to LAN2 (where LAN1 and LAN2 are identical, but totally separated).... (And I want the two networks to stay that way in case of "emergencies").

Hmm, as I guessed this is probably more complex than I thought. Anyway, LAN1 has its own printer (no color), so it's OK anyway :)

Thanks for sharing your thoughts !

message edited by nooner


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#7
September 16, 2015 at 02:41:48
The switch would join the two networks into one, so you would immediately have an IP address conflict between the two routers.

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#8
September 16, 2015 at 10:41:44
Ok, if this were me, I'd split the scope between the two routers.

Here's what I'm talking about.

LAN1
Router IP: 192.168.50.1
SM: 255.255.255.0
DHCP enabled = Yes
DHCP Scope = 192.168.50.100 to 192.168.50.175

LAN2
Router IP: 192.168.50.2
SM: 255.255.255.0
DHCP enabled = Yes
DHCP Scope = 192.168.50.176 to 192.168.50.254

That leaves 192.168.50.1 through 99 excluded and available for static assignments. Since 1 and 2 are used by the routers and 25 is the printer.....everybody can access the printer and there are no IP conflicts and should one side fail all clients can now get DHCP from the other router.

This is of course assuming 70+ IP's is enough for both your LAN's. If not, supernet it to /23 or /22 and you'll have tons of available IP's for both LAN's.


It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***

message edited by Curt R


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#9
September 16, 2015 at 12:52:43
All of this would be a moot point if the proper hardware had been installed.

Google dual wan port router.

This single router will auto failover if a link goes down seamlessly to the clients. You even configure them to use BOTH links at the same time for better bandwidth utilization.

Answers are only as good as the information you provide.
How to properly post a question:
Sorry no tech support via PM's


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#10
September 16, 2015 at 13:27:44
Fascinating discussion; and the two solutions (Curt R's and Wanderer's) are most interesting...

Curt's would appear to require the operator to activate the switch over of course... Whereas Wanderer's makes it all happen without intervention (once configured correctly)?

Shall keep this post for future reference...


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#11
September 16, 2015 at 14:14:45
Actually, with two separate routers configured as I said and plugged into a single non-managed switch (or the same VLAN of a layer 2 or 3 switch), failover would be instantaneous. Setup as I said, both routers would be operating at the same time. Should one fail, clients connected to the failed router would have to open a command prompt window and do the following:

ipconfig /release
ipconfig /renew

and they'd get DHCP from the remaining router and have connectivity back immediately.

While I honestly believe wanderer has the correct solution I didn't mention it because I was staying within the realm of what the OP already has in place. If you already have two routers, you don't want to go buy a third and then leave the first two sitting collecting dust.

But having said that, if I were setting this up for someone with nothing in place, I'd go dual WAN router for sure as it's the better solution.


It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***

message edited by Curt R


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#12
September 16, 2015 at 14:39:21
The problem is that I understood the OP to say that some computers had to use one router and other ones (for some unspecified reason) needed to use the other one. I took this to mean that some specific computers had to use the second router. This rules out any general DHCP solution. I guess you could use DHCP on one router for the computers that needed to connect to it and fixed addresses on the second one. A little messy when you need the failover to happen.

The dual wan port router sounds to be the best solution, but is an additional expense. But it may be that I misunderstood what the OP was asking.


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#13
September 17, 2015 at 02:14:05
Thank you all for interesting and swift answers. I understand that I will face some sort of IP-conflict if I just connect the two networks as they are, so I won't. (From your intelligent advice I learnt that I probably could get it to work either by purchasing a Dual wan port router, or change the Ip-scopes in the routers respectively).

My strange question origins from the fact that my office used a DSL Internet (8mb/s) and then we invested in a highspeed one ("fiber" 100mb/s). To make things easy we configured the new net (router) exactly as the old one and just connected everything to it.

Before our supscription of the old net (DSL) was ended, the high speed Internet went down for two days (which made me temporarily reconnect the old one again, which also made me realize that it should be a good thing to still have it available). During the 6 months we've had the new net, it has gone down twice (1:st for 2 days, and then recently for 6 hours. Our company cannot afford to lose Internet access at any time whatsoever).

Now some comps are still connected to the old net (mostly by pure laziness, but also to make sure even the old net is up and running, and they are consequently not connected to a special colour printer... but it isn't really a problem - they user several comps, so when they need to special print they just use another computer).

Thank you again !
Cheers!


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#14
September 17, 2015 at 06:39:22
✔ Best Answer
The dual WAN router is your best solution at this point. While it is an extra expense, it will handle the failover automatically which, once properly configured, will not require any further configuration by the admin.

In fact, unless you can set it up to notify you if your primary provider goes down (recommended as it allows you to contact them to ensure they are aware) you wouldn't even notice it had happened.

It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.

***William Henley***


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