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In our office, all machines use IP address 192.168.0.x with subnet mask 255.255.255.0, the network setup is as below:

Network setup

We only had routerA before. But since its wireless signal is too weak (much weaker than a typical wireless router), we decided to use the spare routerB as an access point. My colleague and I agreed that we should turn off the DHCP for the routerB.

There are two things that we don't agree on:

1) He said we should, to play safe, simply assign routerB an IP address (e.g. 192.168.1.1) that is outside our network because we are using it as a switch and IP address is irrelevant, while I think it should still has an IP within the 192.168.0.0 network.

2) He said we should not turn off the access point function of routerA even we now have routerB as the access point because both routers can share the wireless workload. What I think is that, the access point function of routerA should be turned off because both routers are just sitting next to each other, and they are just announcing the same SSID. It seems it will do more harm than good because their signals will interfere with each other, which decreases signal strength.

Is there any problem giving the routerB an IP address outside our network? And should we leave the wireless function of routerA turned on, or should it be turned off?

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5 Answers 5

up vote 9 down vote accepted

Giving "Router B" an IP address in your LAN subnet would allow you manage it easily. There's nothing that's more "safe" about giving it some oddball IP address-- you're just making it harder to manage.

As long as "Router A" and "Router B" have their wireless radios set to different non-overlapping channels the amount of interference they'll create with each other will be negligible and since you're using the same SSID on both clients will roam between them. Since they're physically very close to each other, though, I don't expect you're going to see an appreciable quantity of roaming.

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Putting it on the same network makes it harder to segment out traffic coming from wireless devices and could cause you to expose your network. And RouterA and RouterB will be fighting for clients even if they're on different channels. Devices could roam back and forth just through fluctuations in the EMF atmosphere of the room. The devices receiving are going to be seeing differences of fractions or power. Move a foot to your left and you might try to connect to the other router. Someone turns on bluetooth, same thing. Same channel or not, APs next to each other on same SSID would be bad –  PsychoData Feb 19 at 17:24
    
@PsychoData - Assigning a different IP address to the LAN-side of "Router B" has next to nothing to do with putting traffic from the wireless network into a different "segment" (VLAN, subnet, etc). re: both APs beside each other broadcasting the same SSID - I have no representative environment with which to test, but different clients are going to behave differently. It has been my experience that many Wi-Fi radios will "hang on" to their association with an AP for far longer than they should when another AP with a better signal is available. –  Evan Anderson Feb 19 at 17:32
    
re: radios Agreed they normally hold on for a good while even while there is a better connection, but that doesn't mean that their going to have an easy time choosing between A or B when they're essentially equal. No point putting it in that position. Re: assigning a different LAN address would make no sense by itself. You would also need to change DHCP on B, adjust the appropriate interface on A to have a matching address, ideally assign it a separate VLAN, and configure ACLs or other mechanisms for segmentation. But, one of those steps IS a different WLAN B IP address. –  PsychoData Feb 19 at 17:37
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Is there any problem giving the routerB an IP address outside our network?

Sure, you won't be able to manage it.

And should we leave the wireless function of routerA turned on and should it be turned off?

Since they're right next to each other you won't get really any benefit and if they aren't very good Access Points, they could interfere with each other.

You are trying to handle the fact you have poor coverage as per the beginning of your post. So just move your RouterB to another location and handle the coverage issue fully so both wireless device cover their own area.

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As said in other answers, there won't be a big problem by keeping the Router B IP address in a different subnet, besides you won't be able to manage it unless you temporally change your host IP addres to the subnet of it. For convencience I would put them both in the same subnet so I can manage them while keeping Internet connectivity.

There's no security improvement by keeping it in a different subnet, since security in a router primary depends on the password of the management account, which never should be left on defaults "admin, admin".

Now, on the AP side, if you're going to leave both routers with WiFi AP mode, you must keep them on different non overlapping channels and with different SSID. So you can choose, which network is more convenient, depending on the client position.

Could I add: Why not use the Router B as the only one in the network? Since you don't say that it is going to be in another room acting as a range extender, it could do the job as router and AP alone without hassle, and reducing the potential points of failure in your network (The fewer, the better).

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1) He said we should, to play safe, simply assign routerB an IP address (e.g. 192.168.1.1) that is outside our network because we are using it as a switch and IP address is irrelevant

Play it safe from what? I don't see any inherent "danger" in assigning it an ip address in your existing subnet. If you want to manage it without having to jump through some hoops then assign it an ip address in your existing subnet. Ask him to explain, with context, what he means by "play it safe".

2) He said we should not turn off the access point function of routerA even we now have routerB as the access point because both routers can share the wireless workload.

You brought RouterB into the mix because RouterA wasn't cutting it. So why would you continue to use RouterA? If I have to bring in another piece of equipment because my current equipment isn't doing the job then I'm going to get rid of the equipment that isn't doing the job.

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1) He said we should assign routerB an IP address outside our current network(e.g. 192.168.1.1)

You get to win on this one it sounds like. If your wireless devices need access to stuff on the 0.X network then, unless you want to set up some routing between the two, set the router as a 0.X address, split you DHCP scope between the routers or set a DHCP helper address on the second router pointing to the first. also make sure that NAT and DMZ are off

2) He not to turn off the AP function of routerA because both routers can share the wireless workload.

You get to win on this one as well. It makes no sense to have them both broadcasting next to each other, especially on the same channel. If they werent right next to each other, then put one on the other side of the room and put it on a different channel. SSID will still be the same for both. Since you're adding the second because the first one performs poorly, I would stick to just the second

Is there any problem giving the routerB an IP address outside our network?

The only real concern is security. If some nefarious hacker got on your wifi, you don't have them on a separate network where you can say "oh, no clients on our 2.X wifi network are allowed to access SecureServerB"

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