Static IPs or DHCP reservations?

[wayner]

I am trying to bring some order to my LAN as I now often have around 100 devices. Should I use static IPs or DHCP reservations?

DHCP reservations are somewhat simpler and you don't have to enter a Gateway and DNS server info. It can also be administered centrally through your router's web UI (I have an Asus RT-N66U router running Merlin). And you can always do a DHCP reservation - with some devices you can't always do a static IP - Harmony Hubs are one example.

I don't know if all routers let you do this but my router also lets you do DHCP reservations for IP addresses outside of the DHCP range. For example my DHCP range is 192.168.1.100-185, but I am able to do DHCP reservations with a 192.168.1.200 IP address.

Static IPs presumably give you more control and you will always get that particular address, even if it causes a conflict.

Anyone have an opinion?

And how does this all change in an IPv6 world where we no longer need NAT?

[KeithAbbott]

Only use static IPs as a last resort, for all of the reasons that you mentioned.

[EnterNoEscape]

Originally Posted by KeithAbbott

Only use static IPs as a last resort, for all of the reasons that you mentioned.

I used to use reserved addresses, but I find statically assigned IP addresses to be the more reliable route because if DHCP is not working for any reason, at least your servers are probably still doing their job. You could also end up with a server not having an IP address depending on how it handles renewing it's IP address.

I maintain a spreadsheet of of my DHCP pools and static IP addresses for all of my subnets. I know configuring DNS, setting the IP addresses and maintaining a spreadsheet sounds like more work, but how many times are you re-imaging/adding to your servers in one year? Once I got in the habit of assigning static IP addresses, I stopped thinking of it as a chore. Also if my DHCP service died irrecoverable for any reason, I don't need to re-enter all of my reservations and I have a real backup of how I configured everything.

[KeithAbbott]

Originally Posted by EnterNoEscape

I maintain a spreadsheet of of my DHCP pools and static IP addresses for all of my subnets. I know configuring DNS, setting the IP addresses and maintaining a spreadsheet sounds like more work, but how many times are you re-imaging/adding to your servers in one year? Once I got in the habit of assigning static IP addresses, I stopped thinking of it as a chore. Also if my DHCP service died irrecoverable for any reason, I don't need to re-enter all of my reservations and I have a real backup of how I configured everything.

I salute your home network work ethic!

[NetworkGuy]

Originally Posted by EnterNoEscape

I maintain a spreadsheet of of my DHCP pools and static IP addresses for all of my subnets.

I use reservations for all of my devices (30+). I use different ranges for different type of devices:

• 1-50 Computers & NAS
• 51 - 60 Printers
• 61 - 70 HDHR
• 71 - 80 HD300's & Android TV
• 81 - 90 TV's and Music Player
• 91 - 100 Harmony Hubs
• 100+ Wireless

I also maintain a spreadsheet, but I populate it by copying the reservation page from my router. That way I do not fat-finger the MAC addresses.

[KeithAbbott]

And just to add to the discussion, I only use reserved addresses if there is a need to. Almost all of the infrastructure (servers, wi-fi access points, printers, etc.) work best with a predictable IP address. Most of my client devices do not have a reserved address, I let DHCP assign the IP address of it's choosing.

[wayner]

What tools are you folks using to get a dump of all of the IPs, etc from your LAN? Although it is meant for other purposes I find WakeMeOnLan to be very useful as it shows MAC, IP, Network adapter company, etc. And you can then copy the data into a spreadsheet. Are there other tools out there that are better?

FYI, I am working on a simple shell script to allow you to take a text file and use that to add DHCP reservations. My router is an Asus RT-N66U but this should work for most or all Asus routers.

The script looks like this:

nvram get dhcp_staticlist | tr -d'\n' > dhcpnew.txt
cat dhcp_add.txt >> dhcpnew.txt
nvram set dhcp_staticlist="$(cat dhcpnew.txt)"

You would execute this in an SSH session on your router from the jffs partition. The file dhcp_add.txt would contain the new info to be added to the reservations and would look like this:

<A0:30:A6:0D:76:4E>192.168.1.200>WifiLightKitchen<B8:27:EB:BC:F0:2C>192.168.1.201>RasbPi1

which is in the format "<MAC>IP>NAME" - and repeat for as many that you want to add.

[wayner]

Originally Posted by KeithAbbott

And just to add to the discussion, I only use reserved addresses if there is a need to. Almost all of the infrastructure (servers, wi-fi access points, printers, etc.) work best with a predictable IP address. Most of my client devices do not have a reserved address, I let DHCP assign the IP address of it's choosing.

I kind of disagree, since more of the clients are infrastucture. A Hue lighting hub is one example - I want it to have a predicatable IP as my Home Automation system, Control4, has the Hue's IP as a parameter in its Hue driver.

That is become the case more often with IoT devices.

I also find it useful to have predictable IP addresses for stuff like Sage extenders, even though it doesn't really matter for functionality.

[KeithAbbott]

Originally Posted by wayner

I kind of disagree, since more of the clients are infrastucture. A Hue lighting hub is one example - I want it to have a predicatable IP as my Home Automation system, Control4, has the Hue's IP as a parameter in its Hue driver.

That is become the case more often with IoT devices.

I also find it useful to have predictable IP addresses for stuff like Sage extenders, even though it doesn't really matter for functionality.

I don't think we are disagreeing. If you look at the first sentence of my post:

Originally Posted by KeithAbbott

...I only use reserved addresses if there is a need to.

All of my Sage extenders have a reserved IP address, since there are times that I need to reboot the extender, etc. I don't have Hue lighting, but it sounds like you found a need to use a reserved IP address. My point really was, for client devices like laptops, desktops, tablets, etc., I let DHCP take care of assigning the IP address.

[EnterNoEscape]

Originally Posted by KeithAbbott

All of my Sage extenders have a reserved IP address, since there are times that I need to reboot the extender, etc. I don't have Hue lighting, but it sounds like you found a need to use a reserved IP address. My point really was, for client devices like laptops, desktops, tablets, etc., I let DHCP take care of assigning the IP address.

I'll agree with reserved addresses for anything else whereby it might be difficult or not possible to assign a static IP address.

I have plenty of friends that think I'm nuts about this, but I tend to run my house a little like a small enterprise.

[KryptoNyte]

Originally Posted by EnterNoEscape

I have plenty of friends that think I'm nuts about this, but I tend to run my house a little like a small enterprise.

I have friends like that, too. They think I'm nuts, right up until I fix their computers, then everything seems to be okay. Most of them still believe it's some form of magic, which I have encouraged, for obvious reasons.

[EnterNoEscape]

Originally Posted by KryptoNyte

I have friends like that, too. They think I'm nuts, right up until I fix their computers, then everything seems to be okay. Most of them still believe it's some form of magic, which I have encouraged, for obvious reasons.

Most of my friends are at my level of technical expertise and specialize in various things that I know much less about. They know full well when they are taking a shortcut with caveats and I have no problem with pointing it out.

[KarylFStein]

I use dnsmasq on a couple Linux VMs, (replicated storage via DRBD so I can take a VM offline and not loose DNS/DHCP). I've found this to be much more flexible than when I just used the router's DHCP server. It is also fairly easy to use and made it pretty painless to adopt IPv6. I also maintain a spreadsheet. AND I have a naming convention for devices .

My main rule of thumb is to assign a static IP for devices that need to be accessible remotely through the firewall and leave the rest to DHCP. I don't use static DHCP bindings. Since dnsmasq handles DNS and DHCP I can just go to e.g. pr2s1 to get to the printer in the second floor study.

[panteragstk]

I use reserved IP for anything I want to control or access a GUI of some sort. The only thing that isn't included in that would be my phones and laptop. My main desktop doesn't have a reservation, but it tends to grab the same IP anyway.

My directv, android TV, AP, wifi camera, etc all have reserved addresses just to make things simple for what I'm wanting those devices to do.

[NetworkGuy]

Originally Posted by EnterNoEscape

I have plenty of friends that think I'm nuts about this, but I tend to run my house a little like a small enterprise.

I will even admit that I have a Network Diagram.

[tmiranda]

I used to just let DHCP do its thing, then I got bit in the a$$ trying to fix a network issue and recently went to static IP addresses

[stuckless]

I use a single DHCP reservation for my unRAID server (runs sagetv and a few other things)... everything else is DHCP.

[wayner]

My router let's me assign a DHCP reservation that is outside of the actual DHCP range. I have the range set to 192.168.1.100-185 but I can assign a DHCP address of 192.168.1.200. Is that the way things typically work?

[KeithAbbott]

Originally Posted by wayner

My router let's me assign a DHCP reservation that is outside of the actual DHCP range. I have the range set to 192.168.1.100-185 but I can assign a DHCP address of 192.168.1.200. Is that the way things typically work?

Yes.

[UgaData]

I use a combination Static IPs and DHCP reservations (for servers (always static), Printers (static) and reservations for devices that really should always the same IP address, which for me, is any device that is in regular use on my network) and just plain old DHCP so computers and devices not always on my network can still connect.
As a rule of thumb the DHCP range of assignable addresses are limited (usually to around 5 or 10 IPs) and do not overlap the static or reserved addresses (for reserved IPs I let DHCP assign an address first, then create a new reservation outside the range assignable by the DHCP server).

To keep track of IP addresses I use 1 of 2 programs to scan and note what devices are on my network. One is Angry IP it is freeware (I think). The other is Solarwinds IP Address Tracker and it is free.