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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.
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.
> [...] i have used for that, 4 AC2600, in AP mode, and the modem/router
> is managing the DHCP.
What is your "the modem/router"?
> When more than 20 devices are connected, the modem / router overloads,
> and no more the internet.
What, exactly, do you observe when there is "no more the internet"?
How do you know that the problem is related to DHCP?
> [...] the devices are the ones that set the lease time. [...]
No.
> [...] the dhcp server set the lease time.
Yes. And a typical Netgear router does not let the user change its
default (24h) lease time. So, again, what is your "the modem/router"?
20 client devices is not a large number. But, as the others have
said, if many different client devices connect at different times, the
DHCP server may have problems, even if only 20 client devices are
connected at any one time.Hi..
antinode wrote:
> [...] i have used for that, 4 AC2600, in AP mode, and the modem/router
> is managing the DHCP.
What is your "the modem/router"?
> When more than 20 devices are connected, the modem / router overloads,
> and no more the internet.
What, exactly, do you observe when there is "no more the internet"?
How do you know that the problem is related to DHCP?
> [...] the devices are the ones that set the lease time. [...]
No.
> [...] the dhcp server set the lease time.
Yes. And a typical Netgear router does not let the user change its
default (24h) lease time. So, again, what is your "the modem/router"?
20 client devices is not a large number. But, as the others have
said, if many different client devices connect at different times, the
DHCP server may have problems, even if only 20 client devices are
connected at any one time.Hi
There is a lot of answer and a lot of question ... I have no much time now to answer and i'll come back tonight, bur i can first give the model of the gateway : https://www.mtlcable.cz/other/Technicolor_TC7210_datasheet.pdf
Thank a lot for your attention, and i will come back tonight to explain my exact situation, because, it's not so simple Thanks
myersw wrote:
Last I knew the dhcp server set the lease time. The router has the dhcp server.
Correct, I don't know why I said that? I was probably thinking of a server? I was sober when I posted that? Senior moment :smileyhappy:
The rest of the post holds though. It might be possible to get into the firmware using TFTP or telnet interface and change the default 24 hours to something smaller as it is a variable held in NVRAM if it could be located and somehow changed I guess? Hmm, see HERE as there was a question about this.
Possible some routers have an option for lease time too?
Not sure about consumer grade router vendors and ability to set lease time. Most of my consumer grade routers were running OpenWRT/LEDE or DD-WRT both of which allow you to change the lease time to whatever you want. Started with DD-WRT on a WRT54G back in 2006. DD-WRT usually ran better then the OEM firmware for me until the r8000. Of course these 3rd party firmware folks are trying to take a consumer grade router to the next level. If you are wondering about the r8000 I had with crappy Netgear firmware, it was the crappy firmware that drove me to try DD-WRT on it. Still had what appeared to be driver issues with DD-WRT, therefore my personal opinion that a big part of the r8xxxx and r9000 router issues are due to the binary blobs that BroadCom provides Netgear. They would be providing DD-WRT with them as well as Brainslayer has a license with Broadcom, which you need.
Ability to set lease time exists on my Ubiquiti gateway (their name for router).