C3700 IP Address Reservation Table Full?

[AustinJerry]

I would like to experiment with static IP addresses on my network. However, when I go into Advanced LAN Setup and click on the Add button to reserve an IP address, I get the message that the table is full. I don't see any IP addresses in the table. What am I doing wrong?

[fordem]

It sounds like you're confusing static addresses with DHCP reservations - they are similar but with one important difference - DHCP reservations depend on the DHCP server on which the reservations were created being available - static addresses don't need a DHCP server - they will work even when there is no DHCP server. If you want to experiment with static addressing go to the LAN setup page and find the DHCP server range - reduce the size of the range - it's probably from 192.168.1.2~192.168.1.254 - change it to something like 192.168.1.100~192.168.1.254 or 192.168.1.2~192.168.1.150 - and then assign the static addresses at the device (not the router) in the space you created earlier. The reason you're doing this is to prevent the router's DHCP server from leasing addresses that are being used as static addresses.

[AustinJerry]

Thanks for the clarification. As expected, I was not understanding how it worked. I'll give this a try.

[inteller]

This is a false answer.

The C3700 IS BROKEN when it comes to DHCP reservations.

I want to make reservations and cannot. Just as the OP stated. I don't want static addresses. I WANT RESERVATIONS not static assignments!

[fordem]

There's nothing false about the answer - the OP wanted static addresses not reservations - go read his post again.

[AustinJerry]

fordem wrote:
There's nothing false about the answer - the OP wanted static addresses not reservations - go read his post again.

You are correct, I wanted static IP's. But, to add a reason why, I have been plagued by IP instability. Every day, I would find that a significant number of my devices had been assigned new IP addresses. I use web pages to control several of my networked devices, such as my AVR and my NAS. Every time I tried to access the devices, I found that they had new IP addresses. I never could figure out why, so about a week ago, I replaced the C3700 with a Linksys WRT1900AC, and have not had a single IP address issue since.

Anyone want to buy a slightly used C3700 real cheap? Send me a PM.

[fordem]

If you need a device to be at a specific ip address, you need to use either a DHCP reservation or a static address - if you don't, you have no guarantee that the device will be at whatever address it was at before - it may retain that address, it may not, depending on how dynamic the network is (how frequently devices come & go) and on the DHCP server's lease duration. If I need a device to be at a particular address I use static addressing - the only time I will use a DHCP reservation is when I need to frequently move a device from one network to another AND have it at a particular address - which is quite rare - I will use the same last octet with whatever first three octets are used on the particular network.

[AustinJerry]

Well, I don't recall being able to find a user-definable IP address lease duration. Certainly it should be something like 7 days. Do you happen to know what the factory default lease duration is?

My home network, which consists of 29 devices, is not that dynamic. Each of my home theater components has a network connection, and it is quite likely that the network interface is powered off when I turn the device off (e.g. my TV). But the TV is turned on every day, so I would expect its IP lease to never expire. But it did, and frequently.

It's too bad that the router behaved in this way, because it has soured me on Netgear devices going forward. Sure, it may have been my fault that it behaved this way, but the factory defaults should have made it more stable.

[fordem]

I can't say for certain what the default lease duration on that particular router is, Netgear often uses a 24 hour duration, and they rarely make it user definable on their residential product - personally I think a 7 day duration is excessive (that, by the way, is what Microsoft uses to default to with their DHCP servers) - on a small, "non-dynamic", network, you can get away with it, but for larger networks it's asking for trouble - I've seen networks where the admin has chosen a lease as short as 25 minutes. The thing about DHCP, DHCP reservations & static addressing is this - there is a time & place to use one over the other - most of us don't need to have more than one device at a fixed address (the router) and in that case DHCP will work fine, once the network starts to grow in complexity and specific devices need to be at specific addresses that's when you have to change things. I don't use Netgear's residential equipment - not even in my home network - everything I've purchased comes from their business line - it costs more, but it gives me the flexibility to set things how I want it. It is a sad fact but residential networks have grown in complexity to a point where the average home owner needs to make a decision to either invest the time to learn about the technology or to pay someone who has made that investment to install and maintain the network.

[AustinJerry]

Well, if the lease default is only 24 hours, that could explain why I was seeing frequent new IP addresses. If the lease is not user-configurable, then replacing the router was the right choice for me. My current network IP configuration remains rock-solid.