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AC2600 and DHCP management
Hi everybody.
I have extended a wifi network in a school, and i have used for that, 4 AC2600, in AP mode, and the modem/router is managing the DHCP.
Everything work fine while there is not to...
PatDen wrote:
Not with simply routers i présume.. ?????Correct. These are generally dedicated SERVERS with many ISP lines coming into them depending on requirements. Think of them as large modems that do DHCP. They are fed by wireless access point/repeaters located in various places.
Coffee shops and other local retail places might use a single router depending on the size of the store, as they might assume less than 250 devices connecting at the same time, but they would more then likely have better routers than your standard run of the mill Residential models. ISP speeds would also likely be higher as well.
The basic problem will always be the number of users at one time and the available bandwidth.
it normally should be able. but there's a possibility of DHCP pool exhaustion as NG uses 1 day for lease time. If many devices come and go quickly, it can run out of addresses
Suspect that microchip8 hit on the problem. If you have a number of clients coming and going then the 1 day lease time is probably not a good setting. May want to try 12 hours or even lower. Any devices that are currently connected will stay connected, just renew their lease.
myersw wrote:
Suspect that microchip8 hit on the problem. If you have a number of clients coming and going then the 1 day lease time is probably not a good setting. May want to try 12 hours or even lower. Any devices that are currently connected will stay connected, just renew their lease.
Bill, the devices are the ones that set the lease time. As far as I know no Netgear router determines the device lease time. Changing the lease time can be done, but not all OS's allow that, at least not easily.
Usually that wouldn't be a problem. In olden days when there was dial-up a Least Recently Used list was kept of those attaching. When you dialed in you wound up on a server that had only so many connections available. Once the connections were all make, it searched the list for the oldest connection and dropped that. Worked well because many people stayed connected but not using it at all.
Some ISP's that do not have 'always on' connections (Cable ones do mostly) as some people power down modems when not in use or on vacation. They might plan for that to save needing servers.
So there are 3 questions at work here:
- First and foremost, does Netgear Residential Router use LRU lists and drop an IP Address when 253 are given out and uses the first one on to give to the new connection?
- Does the Netgear router put the IP Address back in the available pool when a device disconnects (is turned off or leaves)?
- Does the OP have more that 253 possible connections?
Hard to say what is going on without 'knowing' those answers I'd say.
This is a clue here, "When more than 20 devices are connected, the modem / router overloads, and no more the internet." First the statement "no more the Internet" is a completely different problem, especially if ALL devices lose it? Secondly, only 20 devices is all it takes to make this happen? Heck, a lot of people would be complaining if this were the case. Yeah, we know Access lists are limited (I think I saw 30 devices?) but not 20 connections.
Modem/Router combo (of unknown make and model) was handling DHCP it seems. It might be the culprit though? Only caveat I can see that would cause problems is the number of expected connections and the ISP speed... and it could be a real problem if the ISP speed is low and a lot of wireless devices connect and are active at the same time. Residential Routers probably can't handle that sort of load.
Last I knew the dhcp server set the lease time. The router has the dhcp server.
myersw wrote:
Suspect that microchip8 hit on the problem. If you have a number of clients coming and going then the 1 day lease time is probably not a good setting. May want to try 12 hours or even lower. Any devices that are currently connected will stay connected, just renew their lease.
Is it possible to manage the lease time in the R7800 ????
yes it's possible. Entable Telnet at http://192.168.1.1/debug.htm
login in Telnet with your pass (telnet 192.168.1.1) and modify the file /tmp/udhcpd.conf file with "vi". Look for "option lease" which is in seconds and set your custom value. Then "killall udhcpd" and start it back again with udhcpd /tmp/udhcpd.conf
