I wanted to reserve a 'static' IP for my security camera

Question

I'm having similar issue.&nbsp; I wanted to reserve a 'static' IP for my security camera.&nbsp; After I pick the MAC address for my camera by clicking the radio button on the left andthe very last is to click 'Apply'.&nbsp; The router starts to refresh and it takes about 30 seconds.&nbsp; I immediately check to see if my camera now has the new IP under 'Connected Devices'under the 'Basic' tab.&nbsp; Instead of expecting the new IP, it dynamically assigned a different IP and the same time the IP I just assigned is still listed under 'Reservation Address' screenin the 'Advanced' tab.&nbsp;What is the problem here?&nbsp;

HappyCat · Answer

If this device is already online when the reservation table is updated, it will continue to have the same IP address until the router itself is rebooted.

The DHCP process looks first in the router ARP tables to see if the MAC address of a device making a DHCP request is already on the network with an IP address. If it is, then the device is allowed to keep that IP address. If it is NOT in the ARP table, then the router looks next to the reservation table to see if the MAC address is in that table. If not, it makes an assignment from the DHCP 'pool'.

Not what we humans would expect, but that's what happens. (and, yes, it has been a major annoyance to me)

Rebooting the router clears the ARP table, so every device on the network makes a request and none of their MAC addresses are in the ARP table, so they get an IP address they way we think they should.

CrimpOn_old · Answer

sydneyl wrote:If a client device does not request IPIf a device does not broadcast a DHCP request, then the router does not respond.&nbsp; Period.&nbsp; If the device starts sending packets across the network using some IP address, devices on the network (including the router) will eventually associate that IP address with the MAC address that is using it and put the relationship in their ARP tables.&nbsp;If a device broadcasts a DHCP request, then the router does as described above:If the device appears in the router ARP table (every device on the network typically maintains an ARP table, but the router knows only what is in its own ARP table), the the router says, "use this IP".If the device MAC address does not appear in the router ARP table, the router then looks in the Address Reservation list.&nbsp; If it finds the MAC address there, it responds with "use THIS IP address" (from the table).If the device MAC address is not in the reservation table, the router picks an IP from the dynamic pool.&nbsp;sydneyl wrote:If your ARP clears out, that must be really annoying!!!Not a problem.&nbsp; The ARP table exists to expedite sending Layer 3 data packets (i.e. IP).&nbsp; Every time a process on the computer (any device on the network) wants to send an Ethernet packet, the network adapter looks at the packet to see if it is a Layer 2 packet (addressed by MAC address for the local network) or a Layer 3 packet (addressed by IP address).&nbsp; If it is an IP address, the network adapter has to know which MAC address to send the packet to.&nbsp; It first looks in the ARP table to see if the IP address is already known.&nbsp; If found, it now knows which MAC address to send the packet to.&nbsp; If not found, the computer issues an ARP lookup request, "who had IP xx.xx.xx.xx?"&nbsp; Some device on the network will respond, "I have this IP.&nbsp; Send packets for that IP to my MAC address".&nbsp; And the computer adds that IP address to its ARP table.&nbsp;This is all automatic.&nbsp; Having the table eliminates the need to issue a request for every packet the computer wants to send.&nbsp;One common situation people often create is having the DHCP 'pool' overlap with address reservations.&nbsp; For example, if the pool is 192.168.1.1 to 192.168.1.99, the user may define reservations for devices as 192.168.1.24, 192.168.1.77, 192.168.1.98 (for example).&nbsp; Suppose those devices are not active on the network and some other device requests an IP.&nbsp; The router may look and see, "oh, no one is using 192.168.1.24, so you can have that one."&nbsp; Then, the device connects to the network and asks for an IP, but the address it is supposed to use is already taken by another device.&nbsp; NOT GOOD.&nbsp;So, the accepted practice is that address reservations should be in a group of IPs that are separate from the dynamic 'pool'.

FURRYe38 · Answer

What model NG router do you have?&nbsp;
What browser are you using to make this configuration? Happens with different browsers?&nbsp;
What firmware version is loaded on the router?

sydneyl · Answer

Took me a few days to nail down the my problem. I recently added a TP Link AP to my home network for the purpose of extending wifi coverage at the house.

The TP Link AP was acting as a DHCP serverwhich I wasn't aware of so as my main Netgear R8000 router. I never thought the TP Link was handing out IP's.

The 'Address Lease Time' had a default of 1 minute so it kept renewing IP's to the cameras. I made sure the address range on the TP Link was isolated from

the Netgear. That resolved my issue!

sydneyl · Answer

A side question.&nbsp; Just so I understand exactly how the addresses listed under 'Address Reservation' table/list on my Netgear R8000 work.&nbsp; Say I have a client device with MAC addressMAC123 and I manually added an entry (IP) for this device to be 192.168.1.200 in the 'Address Reservation' pool for MAC123.&nbsp; Assuming the client device does not allow you tophysically assign a static IP on the device.&nbsp; At the moment the Netgear R8000 sees this device connected and 'online', it immediately sends out 192.168.1.200 to the device, correct?&nbsp;Under what condition/scenario this client device would not receive the x.200 address from the router?&nbsp;

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I wanted to reserve a 'static' IP for my security camera

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