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More Fun with WiFi -- Possible IP Address Issue?

Posted: Mon Jul 23, 2012 11:08 am
by pingsteve
As our stake has moved to using more of the on-line materials from LDS.org, I'm hearing more and more concerns about people that are unable to connect to the Internet.

Last week I helped a teacher whose Mac was not receiving an IP address from the DHCP server. After restarting the wi-fi connection on the computer a few times it eventually connected and received an IP address.

Yesterday I heard a similar account from a teacher that assumed I had fixed her wi-fi connection problem, but I was not even in the building when the problem was resolved.

In both cases, we have 3 wards in the buildings, and the ward meeting times overlap. My best guess is that with people coming and going we are exhausting the entire pool of available IP addresses. Between smart phones, iPads and laptops I am sure there are quite a few devices that connect to the DHCP server.

Is there a way I can track how many IP addresses are in use in the building at a given time? Also, how can I check the size of the DHCP pool?

Posted: Mon Jul 23, 2012 11:46 am
by jdlessley
From the cases you mentioned this sounds characteristically like you are running into the limited available IP addresses issue.
pingsteve wrote: Is there a way I can track how many IP addresses are in use in the building at a given time?
Not without access to the router interface.
pingsteve wrote:Also, how can I check the size of the DHCP pool?
Each of the three Cisco router/firewalls the Church has in service have default setups. The current one, the Cisco 881W, has 9 static IP addresses and 52 dynamic addresses as the church default. Higher numbers are available by working with the GSC. If you don't know if the number of addresses have been increased then you (if you are the STS) can contact LUS to find out your configuration situation.

Posted: Mon Jul 23, 2012 12:05 pm
by pingsteve
jdlessley wrote:From the cases you mentioned this sounds characteristically like you are running into the limited available IP addresses issue.

Not without access to the router interface.

Each of the three Cisco router/firewalls the Church has in service have default setups. The current one, the Cisco 881W, has 9 static IP addresses and 52 dynamic addresses as the church default. Higher numbers are available by working with the GSC. If you don't know if the number of addresses have been increased then you (if you are the STS) can contact LUS to find out your configuration situation.

It is the 881W. I'm the HC over technology but I'll talk to my STS and have him contact the GSC.

Posted: Mon Jul 23, 2012 12:12 pm
by dr12dave
In our buildings we were having a similar issue. The first thing we did was to have HQ setup a separate Static IP subnet on a port on the Cisco 881W router. Then we setup all of the ward/branch computers (these being the absolutely vital ones) with Static IPs and get another small switch from the FM Group to run this Static IP subnet; the original one to run the WIFI devices which are all DHCP. The other thing thing that was done, if I remember correctly was to lower the IP Lease Time to one hour or less if possible. Otherwise that lease is typically for 24 hours, I believe. As people come and go with their WIFI devices, the Leases stay intact, even though the device is gone, not allowing anyone else to use them. The other possibility is to put another router off of the Cisco router and make it DHCP with a public subnet like 192.168.1.0, then there would be 254 available IP addresses. Good luck with this.

Posted: Mon Jul 23, 2012 12:42 pm
by russellhltn
dr12dave wrote:Otherwise that lease is typically for 24 hours, I believe.
Usually it's an hour. I've seen it as high as two hours for a church router.

dr12dave wrote:The other possibility is to put another router off of the Cisco router and make it DHCP with a public subnet like 192.168.1.0, then there would be 254 available IP addresses. Good luck with this.

I wouldn't suggest that until more is known about the new authentication system coming out. Additional routers may create problems and allow users more access then they would otherwise be allowed.