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[Taxi_Driver]

Having thrown the useless netgear dgn1000 away (actually was the fault of the orange or vodafone firmware it had on it, and nigh on impossible to get back to netgear firmware), I bought a netgear dgn2200.
Far better router, so far......
But i have discovered that the wifi printer i have doesnt like WPA2 encryption (and if i change it to anything less, like WEP, the dgn2200 slows down from 300/150M to 56M)

So my solution to this....was leave the dgn2200 at WPA2, then link to an older wifi router with cable, set this older one to use WEP and let the printer connect to this router.

Works a treat, my netbook connects to dgn2200 and can see the printer connected to other wifi router.

Ok, at first glance it looks like i have compromised the whole network to WEP encryption.....however i have set the older router not to broadcast its SSID, so unless you know its there........your not gonna find it....possibly  However im not too concerned about it.

Now's heres the mystery to me....

dgn2200 is set to be DHCP server from 192.168.0.2 to 192.168.0.63
older router is set to be DHCP server from 192.168.0.64 upwards.

older router has a static address of 192.168.0.254 and nowhere on the old router can i find anything about the address of the DHCP server.......so i am assuming it should be serving clients connected to it.

My netbook when connected to the dgn2200 at the moment has an ip addy of 192.168.0.2
If i disconnect it and connect to the old router, it still get's the same ip addy. I was expecting it to get anything from 192.168.0.64 upwards 

Netbook is set to get settings auto.....

Can anyone explain this please.....

[TheBoy]

Disable DHCP on one of them, you only need 1 DHCP on a network.

[TheBoy]

But to answer your question, DHCP client will go to its last DHCP server asking to reuse the old address, and if it is granted permission, thats what it will use.

(Thats an over simplification, but will do for now).


If you want to understand how DHCP works, search for DORA (Discover, Offer, Request, Acknowledge).

[aaronjb]

Not knowing your operating system (I'm going to assume Windows) you'll probably find that you still have a valid (as far as your client is concerned) DHCP lease when you connect to the new router.

In that case, rather than the full DHCPDiscover (a broadcast packet to the entire network)->DHCPOffer (unicast from the DHCP server to client)->DHCPRequest (unicast from client to DHCP server)->DHCPAck (unicast from DHCP server to client) conversation, your PC will be simply doing a DHCPRequest straight to the original DHCP server.

If you release your IP address and then get a new one you should force Windows to do a DHCPDiscover, at which point it'll find the first responding DHCP server. Note though that this might not be the router you're connecting to - it all depends who is fastest!

In laymans terms, a full DHCP conversation goes:

PC, yelling to the room: "HELLO! CAN ANYONE GIVE ME AN IP ADDRESS?"
All DHCP servers: "Yes, I can, would you like 192.168.x.x?"
PC, back to the first DHCP server he heard: "Great, thanks, 192.168.x.x you say!"
DHCP back to PC: "That's the one. Have at it."

The abridged renewal conversation is more like:
PC, to DHCP server he talked to last time: "Hey Bob, I had 192.168.x.x before, can I still have it?"
DHCP server back to PC: "Sure, go for it, nobody else is using it."


Incidentally can you not configure the second AP to be a DHCP forwarder for your main AP? That way you've only got one DHCP server to worry about.

[edit] Must type faster.

[TheBoy]

If you release your IP address and then get a new one you should force Windows to do a DHCPDiscover, at which point it'll find the first responding DHCP server. Note though that this might not be the router you're connecting to - it all depends who is fastest!

But if one of the offers is its previous IP, it will request that, even if previously expired, or released.

[CaptainZok]

How about, piece of cat5 from new router to printer, job jobbed.

[Taxi_Driver]

Thankyou TB and Aaron  ......i understand now 

Mr Zok....Printer has wifi and usb only 

[aaronjb]

If you release your IP address and then get a new one you should force Windows to do a DHCPDiscover, at which point it'll find the first responding DHCP server. Note though that this might not be the router you're connecting to - it all depends who is fastest!

But if one of the offers is its previous IP, it will request that, even if previously expired, or released.

Good point, well made