AC68U - Manually Assigned IPs - inside or outside the DHCP Pool range?

[Livin]

I prefer to use DHCP reservations (aka Manually Assigned) - Some devices I set static IP on the device, others I do not.

Do I need to ensure the DHCP Pool settings, in the ASUS, cover the Manually Assigned address range also - os will the router properly handle IPs that I set in the Manually Assigned section, even if they are not in the DHCP Pool range?

My ultimate goal is to force all new clients into a very small range... .245-254 so I can limit any rogue connections and also quickly identify them.

thx

 

[L&LD]

Use the small DHCP range for any new clients and use the rest for your known devices as Manually assigned. Works exactly as you would expect it to.

 

[joegreat]

Use the small DHCP range for any new clients and use the rest for your known devices as Manually assigned. Works exactly as you would expect it to.

I confirm!

 

[sfx2000]

I prefer to use DHCP reservations (aka Manually Assigned) - Some devices I set static IP on the device, others I do not.

Do I need to ensure the DHCP Pool settings, in the ASUS, cover the Manually Assigned address range also - os will the router properly handle IPs that I set in the Manually Assigned section, even if they are not in the DHCP Pool range?

My ultimate goal is to force all new clients into a very small range... .245-254 so I can limit any rogue connections and also quickly identify them.

thx

Static IP's should always be outside of the DHCP scope - within the DHCP scope, you can assign IP's per MAC address, but for nodes that you want to never change...

Case in point - three servers - I assigned them 192.168.1.20/30/40 manually on the device itself - for media servers, I have 192.168.1.25/35/45, the Printer/Scanner AIO device is 192.168.1.50, and my supplemental AP's on 192.168.1.21/31 - for the rest of the client nodes, I let them live on the DCHP scope of 192.168.1.100-150, and that is so that we don't get collisions between static and dynamic nodes.

For the Guest Network - I use 192.168.100.2 thru 192.168.100.10, with a GW address of 192.168.100.1, again, DHCP managed for them. Also set AP isolation, so we don't run into weird lower layer conflicts, but all the guests have direct access to/from the internet.

(note - I'm using the IP's/Ranges as an example).

HTH...

sfx

 

[RMerlin]

Static IP's should always be outside of the DHCP scope - within the DHCP scope, you can assign IP's per MAC address, but for nodes that you want to never change...

Exactly. A lot of people confuse "static IPs" with "lease reservations". Static IPs, which are manually configured on the network interface, should be outside of a DHCP scope, as they aren't managed by the DHCP server. Lease reservations, which are allocated dynamically by the DHCP server, should be within its scope.

 

[sfx2000]

Exactly. A lot of people confuse "static IPs" with "lease reservations". Static IPs, which are manually configured on the network interface, should be outside of a DHCP scope, as they aren't managed by the DHCP server. Lease reservations, which are allocated dynamically by the DHCP server, should be within its scope.

Absolutely - and FWIW - I don't use DHCP reservations in any event - no need to... it's just one more thing to manage, and it's generally not needed.

Things that don't move around much (NAS, Media Gateways, etc) are static assignments - things that need to be port forwarded to the outside world, Static IP's...

I use DHCP for things like my desktop PC's, laptops, tablets, handsets - they're not dependent on having a fixed IP address, and most modern DHCP servers will likely have some persistence anyways, once a MAC address is bound to an IP, it will generally get the same one...

 

[CiscoX]

Static IP's should always be outside of the DHCP scope - within the DHCP scope, you can assign IP's per MAC address, but for nodes that you want to never change...

Case in point - three servers - I assigned them 192.168.1.20/30/40 manually on the device itself - for media servers, I have 192.168.1.25/35/45, the Printer/Scanner AIO device is 192.168.1.50, and my supplemental AP's on 192.168.1.21/31 - for the rest of the client nodes, I let them live on the DCHP scope of 192.168.1.100-150, and that is so that we don't get collisions between static and dynamic nodes.

For the Guest Network - I use 192.168.100.2 thru 192.168.100.10, with a GW address of 192.168.100.1, again, DHCP managed for them. Also set AP isolation, so we don't run into weird lower layer conflicts, but all the guests have direct access to/from the internet.

(note - I'm using the IP's/Ranges as an example).

HTH...

sfx

Hi.

Did you also manually add ip on the devices interface on your media servers, Printer/Scanner AIO and supplemental AP's ?
So you don't use "Manually Assigned IP around the DHCP list (Max Limit : 128)" on the ASUS router?
If i like to use the Manually Assigned IP around the DHCP list (Max Limit : 128) from the ASUS router, I don't need to add it manually to the devices interface then?

 

[sfx2000]

Hi.

Did you also manually add ip on the devices interface on your media servers, Printer/Scanner AIO and supplemental AP's ?
So you don't use "Manually Assigned IP around the DHCP list (Max Limit : 128)" on the ASUS router?
If i like to use the Manually Assigned IP around the DHCP list (Max Limit : 128) from the ASUS router, I don't need to add it manually to the devices interface then?

I don't use DHCP to manage IP address reservations for devices that have static IP's - I assign them outside of the DHCP scope...

 

[CiscoX]

I don't use DHCP to manage IP address reservations for devices that have static IP's - I assign them outside of the DHCP scope...

Thanks,

For what I understand, the "Manually Assigned IP around the DHCP list (Max Limit : 128)". You are forcing the client to get the same IP all the time, even if the client is gone for couple of days. So my question is, I don't need to add the IP into the interface of all my devices. I do have lot of smartphones, tables, laptops, xbox360 and i like to give them the same IP without having to enter the IP manually into the interface(static IP).
So I want to Manually Assigned IP around the DHCP list for all my devices:
192.168.100.80
192.168.100.81
192.168.100.82
192.168.100.83
etc

And I have my DHCP range from 192.168.100.115-192.168.1.120 for other devices(friends with smartphones, laptops).
I do have couple of servers running, but they have static IP(manually on interface)

 

[coldwizard]

Thanks,

For what I understand, the "Manually Assigned IP around the DHCP list (Max Limit : 128)". You are forcing the client to get the same IP all the time, even if the client is gone for couple of days. So my question is, I don't need to add the IP into the interface of all my devices. I do have lot of smartphones, tables, laptops, xbox360 and i like to give them the same IP without having to enter the IP manually into the interface(static IP).
So I want to Manually Assigned IP around the DHCP list for all my devices:
192.168.100.80
192.168.100.81
192.168.100.82
192.168.100.83
etc

And I have my DHCP range from 192.168.100.115-192.168.1.120 for other devices(friends with smartphones, laptops).
I do have couple of servers running, but they have static IP(manually on interface)

I read merlin's explanation above differently ...
If in your example you Manually tell DHCP to Assign the following IP around the DHCP list for your devices:
192.168.100.80 mysmartphone1
192.168.100.81 mylaptop1
192.168.100.82 mylaptop2
192.168.100.83 myotherdevice
The IP addresses manually assigned don't need to be sequential so you could
192.168.100.99 Myfavoritenumber
etc

Then your DHCP range must contain those IP addresses so would be
192.168.100.80-192.168.100.120
since the DHCP server is managing those IP addresses.

Your guests would get an IP address within the DHCP range, but not one you have reserved for your devices.

If you configured a printer or other server on it's interface (static IP) you could use 192.168.100.128 but could not use anything within the DHCP range.

 

[L&LD]

I read merlin's explanation above differently ...
If in your example you Manually tell DHCP to Assign the following IP around the DHCP list for your devices:
192.168.100.80 mysmartphone1
192.168.100.81 mylaptop1
192.168.100.82 mylaptop2
192.168.100.83 myotherdevice
etc

Then your DHCP range must contain those IP addresses so would be
192.168.100.80-192.168.100.120
since the DHCP server is managing those IP addresses.

Your guests would get an IP address within the DHCP range, but not one you have reserved for your devices.

If you configured a printer or other server on it's interface you could use 192.168.100.128 but could not use anything within the DHCP range.

No, you're reading it wrong.

 

[john9527]

So I want to Manually Assigned IP around the DHCP list for all my devices:
192.168.100.80
192.168.100.81
192.168.100.82
192.168.100.83
etc

And I have my DHCP range from 192.168.100.115-192.168.1.120 for other devices(friends with smartphones, laptops).

Then your DHCP range must contain those IP addresses so would be
192.168.100.80-192.168.100.120
since the DHCP server is managing those IP addresses.

There is accepted/common practice and then there is strict adherence to the specification.

CiscoX, your setup is in the first category, and many do it that way... and the dnsmasq man page specifically allows it.

coldwizard is the 'strict adherence' method. Microsoft, for one, implements it that way on their servers.

In Merlin history, one of the late 376 builds changed to the strict enforcement and everyone starting yelling they weren't able to obtain leases. In 378 it changed back.

 

[RMerlin]

In Merlin history, one of the late 376 builds changed to the strict enforcement and everyone starting yelling they weren't able to obtain leases. In 378 it changed back.

The bug was in how Asus determined the maximum of allowed leases - they were basing it on the size of the pool. So, an IP pool of 20 (192.168.1.1 to 192.168.1.20 for example) wouldn't let you reserve a 21st IP even if outside that pool. What I did afterward was to make the maximum number of leases equal to either 253 or the pool size, whichever was the largest.

In 378_4585 Asus decided to comment out that dhcp-max-lease calculation, so there's no pool size limitation anymore at this time.

 

[sfx2000]

There is accepted/common practice and then there is strict adherence to the specification.

what specification? Interested to learn this... share what you know...

sfx

 

[john9527]

what specification? Interested to learn this... share what you know...

sfx

OK....so I used the term a little loosely If you do a search on 'dhcp-max-leases' you find a thread where people were quoting documents referring to this this topic (on both sides). If my memory? is correct, the latest was from Microsoft for their servers and stated the manually assigned IPs should be in the defined dhcp range (ie what Asus assumed in their first implementation that Merlin references).

 

[aircoreboy]

From Rmerlin in a previous thread,


"The real problem is, a lot of users got used to allocating static leases outside of the scope, which is wrong. People are mixing up reservations with static IPs.

A static IP is something you configure on the computer's network interface, and which must be outside of the DHCP range.

A DHCP reservation is an IP you reserve within your DHCP scope, so the DHCP server will always allocate the same IP.

In other words: any IP allocated by the DHCP server *must* be within the DHCP range, regardless of whether it's static or dynamic. The fact that the DHCP server can allocate an IP from outside its defined scope is a quirk/bug in itself.

Sadly, a lot of routers (including Asuswrt) allow the definition of a reservation outside the defined scope, which leads to issues such as encountered here.

The correct fix is to either enlarge your DHCP scope to include your reservations, or change your reservations to be within the defined scope. And if your goal is for an IP to be outside of the DHCP range, then you must configure it manually and not rely on the DHCP server to allocate an IP from outside its defined range."


Best explanation I have come across!

 

[CaptainSTX]

While there is some confusion on the definition and perhaps the methodology of establishing static/reserved/sticky IPs in practice what will work maybe dependent on the router's firmware.

I am running Tomato on my primary router. I have set it to a pool of twenty IPs to assign. I have my self assigned, mostly using the reservation capabilities of Tomato twenty seven reserved/static IPs and the Static IPs for my three APs are set using the firmware on them. Every device regularly connecting to my network is assigned a static IP. Network equipment is in one range, video streaming devices another, smart phones, etc.

The use of static IPs has never caused any problems I am aware of on my network.

In the version of Tomato I am using, the default maximum number of DHCP leases is set at 255. I also am able to set the static lease time. I have set it as "infinite". This is useful in that when I look at a list of attached devices/DHCP leases any device with a lease time catches my eye and I can scrutinize any device showing a lease time. This doesn't work perfectly as Apple hardware seems to consider infinite as 99 days but it is another tool to help highlight unwanted connections.

 

[XEQtor]

Message to all Moms & Pops of Lay People.

--------------------------------DECREE-------------------------------
Ms. DHCP Server, I am allowing you to lease out IP addresses ranging from 'A' to 'B' to ANYONE who contacts you for an IP address. You must also tell them that their lease will expire in 'X' seconds, and they must make a new lease request if they wish to remain connected.

I am also asking you to reserve some specific IP addresses to be given strictly only to those who identify themselves by their MAC addresses as they appear in the attached 'Reservation List'.
------------------------------END DECREE----------------------------

From the above Decree, the logical guide is to ensure that the IP addresses in the 'Reservation List' are OUTSIDE the range from 'A' to 'B' to avoid a Device War. But nobody is preventing you from starting a Device War, if you so foolishly wish to.

If you have more than one router, you can have:
Router#1 with range A1 to B1,
Router#2 with range A2 to B2, and,
Router#3 with range A3 to B3.
All 3 ranges must NEVER overlap each other to avoid a Device War.
AND they must ALL share the same 'Reservation List'.

Since this thread refers to Asus, and specifically the AC68U model, and Asus uses the word 'pool' for 'range', let's not confuse Moms & Pops with CinemaScope, KeleidoScope or whatever 'scope'? They should belong to RFC readers and network scientists.

 

[doczenith1]

I am also having some trouble interpreting this thread and would appreciate if someone could let me know if my setup is ok or not. It seems to be working ok.

DHCP range is set to 192.168.1.100 thru .200

I have a computer manually assigned via the router settings using it's MAC address to 192.168.1.2 which I also have ports forwarded to. Should this computer be assigned to a address within the DHCP range?

Thanks for your help.

 

[Chrysalis]

I havent had any issues with dhcp reservation outside the dhcp range.