Question regarding DHCP and setup

[Trsektor]

Hi,

I have the following setup :

All computers currently get ip from the main Router. Now i want to add an access point with its own DHCP for the wifi users. Since it will be running DHCP, will it affect the computer which is connected on the same switch, or other computers? Because from what i know a computer will get an IP from the closest DHCP (if im correct).

Thanks

 

[sdifox]

why do you need dhcp on the new ap?

 

[Fardringle]

If you want the AP to actually have its own separate DHCP setup, then connect the WAN port on the AP to one of the ports on the switch and configure DHCP on the AP to use a different IP address range from the main network (i.e. 192.168.1.1-254 on the main network, and 10.0.0.1 on the AP, for one example).

If they don't actually need to have separate IP address ranges, just disable DHCP on the AP and connect one of its LAN ports to one of the ports on the switch. This way any devices that connect to the wireless network will get IP addresses from the main router, and will also be able to communicate with other devices on the network.

 

[Trsektor]

Thanks both for your reply .

Thats the way i had it up to now (only one dhcp) but the AP keeps dropping the internet or not authenticating the users making the network very unstable and i thought that maybe the main router cannot handle so many connections or maybe there is some conflict between the AP and the main router. Based on that i thought i should try to have it as entirely separate network to see if the problem stops. I just wasnt sure how to configure the DHCP on the AP not to affect the other one.

Basically there was no switch on the left side. It was only the AP with no DHCP enabled.

Shall i replace the current AP with another or should i try adding a switch + DHCP on AP?

 

[sdifox]

Thanks both for your reply .

Thats the way i had it up to now (only one dhcp) but the AP keeps dropping the internet or not authenticating the users making the network very unstable and i thought that maybe the main router cannot handle so many connections or maybe there is some conflict between the AP and the main router. Based on that i thought i should try to have it as entirely separate network to see if the problem stops. I just wasnt sure how to configure the DHCP on the AP not to affect the other one.

Basically there was no switch on the left side. It was only the AP with no DHCP enabled.

Shall i replace the current AP with another or should i try adding a switch + DHCP on AP?

did you setup the secondary ap wiith static ip? and did you setup the ssid to bethe same as the main one? you have have wifi contention if they are the same ssid.

 

[Trsektor]

No the secondary AP does not have a static IP.

Yes they have the same SSID and password because i thought that would create "seamless" connectivity.

Shall i assume both of the above are probably the cause of the problem?

 

[sdifox]

No the secondary AP does not have a static IP.

Yes they have the same SSID and password because i thought that would create "seamless" connectivity.

Shall i assume both of the above are probably the cause of the problem?

Try srtting static ip for the ap. Unless you have commercial hardware that cooperate, there is no seemless handoff between APs, even if they have the same ssid. See if you can dial one of them down in terms of broadcast power.

 

[Trsektor]

Ok will try your suggestions and report back.

Thank you

 

[XavierMace]

We really need some more information on your hardware because most of the people in this thread seem to be assuming your access point is a router that was setup to serve as an access point because people are referring to LAN points on the AP. All of the AP's I've worked with (Cisco, Ubiquity, Sophos, TP-Link) have exactly 1 port on them. The uplink port to a switch. They have no reason to have more than one port on them.

In the case of the Cisco Meraki, you can tell it to either use an existing DHCP server or run it's own on each individual SSID. My "Home" network, it relays to my Server 2012 DHCP server, my "Guest" network is runs it's own segregated network and handles DHCP for that.

Ubuquity's basic AP's don't have their own DHCP server IIRC, unless you're running their appliance as well. Sophos' offerings are meant to pair with a UTM.

 

[imagoon]

No the secondary AP does not have a static IP.

Yes they have the same SSID and password because i thought that would create "seamless" connectivity.

Shall i assume both of the above are probably the cause of the problem?

"Seamless" is a function of the wireless card in the device. Also having multiple IP ranges on the same SSID (as per your image) is not seamless at all and will cause the card to lose connectivity / need to reIP itself if it even realizes it needs to.

 

[Ichinisan]

If you want a private network behind a private network, don't use AP mode. Just get the connections right...

[Internet] --> [(WAN) public router (LAN)] --> [(WAN) private router (LAN)] --> [switch] --> [everything else]

Should use different subnets for public LAN versus private LAN, like 192.168.0.x for one of the networks and 192.168.1.x for the other.

From the private LAN, your computer should be able to access the configuration for both routers by using the correct address.

 

[Trsektor]

hmm ok thanks or your input everyone. I will proceed with the solutions mentioned and will let you know.

@XavierMace : its a Router acting as an AP, it has 1 WAN port and 4 LAN ports. Up to now i was using the lan ports to connect it to the main router.

 

[kevnich2]

If your using a router as an AP - you need to disable DHCP on the AP and continue using the LAN ports. Also assign the router/AP a static IP in the same subnet as your main router, outside of the main router's DHCP pool.

This is another reason I love standalone AP's...

 

[azazel1024]

If your using a router as an AP - you need to disable DHCP on the AP and continue using the LAN ports. Also assign the router/AP a static IP in the same subnet as your main router, outside of the main router's DHCP pool.

This is another reason I love standalone AP's...

Correct, except your last. It is a 30 second configuration change to enable a wifi router to act as an AP. Though if all had an "AP" switch or button, I wouldn't shed a tear.

If you have DHCP still enabled on the router running as an access point, it'll cause serious issues on your network. As above, you need to set a static IP address for the access point that is outside of the DHCP pool on the router (so if the router is giving out 192.168.0.100-.200 you need to set the AP as >.200). LAN to LAN.

Same SSID and password is my preferred method and it works the best on most home networks I have observed. If you use a different SSID the client device is going to assume each SSID is a separate network and treat roaming and connecting between them as such (IE it'll generally only switch if it loses it's connection to the current access point, instead of trying to connect to the strongest access point at any given time).

Doesn't mean there aren't "sticky" clients out there, but so long as there is reasonable separation between access points (so the signal gets modestly weak from the currently connected AP), most clients make fairly good roaming decisions between APs.

 

[Trsektor]

Thanks for your replies.

How is not having a static ip exactly affects the whole network? From all your replies i understand that the AP must get an IP outside of DHCP pool but i havent understood yet why what exactly is causing the problem.

I would appreciated it if somebody explained me.

Thanks again

 

[sdifox]

Thanks for your replies.

How is not having a static ip exactly affects the whole network? From all your replies i understand that the AP must get an IP outside of DHCP pool but i havent understood yet why what exactly is causing the problem.

I would appreciated it if somebody explained me.

Thanks again

It is just tidier. Doesn't really affect the wifi (other than the precise moment it is renewing the lease).

 

[Ichinisan]

Thanks for your replies.

How is not having a static ip exactly affects the whole network? From all your replies i understand that the AP must get an IP outside of DHCP pool but i havent understood yet why what exactly is causing the problem.

I would appreciated it if somebody explained me.

Thanks again

We're talking about the IP address of the AP's LAN interface.

192.168.1.1 - router
192.168.1.2 - access point
192.168.1.100 - first DHCP client...

I do this all the time for WiFi cable modems where the built-in router uses 192.168.0.1

192.168.0.1 - WiFi router in the cable modem
192.168.0.2 - user's own wireless router, configured to behave as an access point (AP)
192.168.0.3 - first address given out by automatic DHCP.

I always have to change the DHCP starting IP address from 192.168.0.2 to 192.168.0.3, then reboot all equipment. That just means the router won't give that IP out dynamically and cause a conflict with your AP.