Fixed IP VS DHCP reservation
Discussion
I have a shedload of different machines on a 48 channel switch connected to my router.
I have reserved IP addresses for some of the more important machines (PCs, radiography machines etc) but from time to time (like today) I get IP address conflicts which f
k up the whole system and lead to some head scratching.
This weekend I’m going to review the whole system to allocate each machine with an address.
Question is, is it best to put s static address on the machine end (for those machines where it’s possible), reserve an address for its MAC address on the router or both?
I have reserved IP addresses for some of the more important machines (PCs, radiography machines etc) but from time to time (like today) I get IP address conflicts which f
k up the whole system and lead to some head scratching.This weekend I’m going to review the whole system to allocate each machine with an address.
Question is, is it best to put s static address on the machine end (for those machines where it’s possible), reserve an address for its MAC address on the router or both?
I always set my DHCP range to 100-250 so that I can assign stuff manually and then keep a spreadsheet of which address is which that way I don't end up with conflicts. You can do address reservation etc as well then that will achieve what you are looking for, DHCP should then only issue that address to that device but it doesn't hurt to belt and braces this stuff.
Guys, thanks so much for the replies, that helps a lot. FWIW it’s the router box provided by the internet company.
I like the idea of separating the DHCP pool from a static pool but over the years I’ve allocated reserved DHCP address to various machines and I’m a bit worried about giving these machines new static addresses in case something ducks up somewhere (as it always seems to with networking, he’ll with anything IT lol)
Or maybe I should just bite the bullet…
I like the idea of separating the DHCP pool from a static pool but over the years I’ve allocated reserved DHCP address to various machines and I’m a bit worried about giving these machines new static addresses in case something ducks up somewhere (as it always seems to with networking, he’ll with anything IT lol)
Or maybe I should just bite the bullet…
It could be a bigger picture type issue.
It could be that your isp provided modem/fw/router/access point box is having trouble with the volume of devices you have connected and is hitting cpu/memory constraints hence the dhcp conflicts.
You might consider either running a separate dhcp server on something like a pi if your ‘box’ allows this or perhaps it’s time to place your existing box into modem mode and use a more powerful router, if your isp allows this.
That said from a management perspective it’s easier mange ip reservations from a centralised point than a per device instance, 1-5 devices perhaps not a lot in it, once your above that I’ll take central every time
It could be that your isp provided modem/fw/router/access point box is having trouble with the volume of devices you have connected and is hitting cpu/memory constraints hence the dhcp conflicts.
You might consider either running a separate dhcp server on something like a pi if your ‘box’ allows this or perhaps it’s time to place your existing box into modem mode and use a more powerful router, if your isp allows this.
That said from a management perspective it’s easier mange ip reservations from a centralised point than a per device instance, 1-5 devices perhaps not a lot in it, once your above that I’ll take central every time
never use dhcp and fixed ip's in that scope
dhcp and reservations yes
a reduced dhcp scope range and fixed ip yes with the fixed ip's been outside of the scope
honestly reservations are a better way to go (if you arnt running domain controllers even then you can just manually assign it after its been reserved)
the only thing that really really needs a static is your DGW
dhcp and reservations yes
a reduced dhcp scope range and fixed ip yes with the fixed ip's been outside of the scope
honestly reservations are a better way to go (if you arnt running domain controllers even then you can just manually assign it after its been reserved)
the only thing that really really needs a static is your DGW
Edited by Trustmeimadoctor on Tuesday 14th June 15:15
A load of great advice here-thanks gentlemen!
If I may and in no particular order :
1) I have about 40-50 machines on the router.
2) It’s a “pro” version router so I don’t think it’s a bottleneck
3) Do I take it then that my belt and braces approach of putting a static address on a machine AND reserving this same address in the DHCP range on the router is not good?
4) At the moment my DHCP range is 90-150 and within this there are some machines with static IPs.
Wouid it be ok to change the DHCP range to say 151-200? That way I can avoid these static addresses being hijacked by the DHCP on the days they are not turned on, which I think is what may be happening.
Are there any down sides to changing the DHCP range in this way?
If I may and in no particular order :
1) I have about 40-50 machines on the router.
2) It’s a “pro” version router so I don’t think it’s a bottleneck
3) Do I take it then that my belt and braces approach of putting a static address on a machine AND reserving this same address in the DHCP range on the router is not good?
4) At the moment my DHCP range is 90-150 and within this there are some machines with static IPs.
Wouid it be ok to change the DHCP range to say 151-200? That way I can avoid these static addresses being hijacked by the DHCP on the days they are not turned on, which I think is what may be happening.
Are there any down sides to changing the DHCP range in this way?
For several years now we had localised IP addresses as my wife calls them or Reserved DHCP addresses to be technical
As we have different devices ie
Computers + Printers
Network Storage
Smart Speakers
TV sets
TV Boxes
And as equipment is changed from time to time sand more stuff is added I have a sort of block think of 20 addies for each section
If say I bought a new network drive I would note its mac address and look at the list and then allocate the next available Network storage ip against it
Sound s a bit anal but it makes it easier to know where the equipment is on your router
Recently though we had an issue with phones appearing with different local addresses and this is due to an android update that pushes the device to use a randomised MAC
As we have different devices ie
Computers + Printers
Network Storage
Smart Speakers
TV sets
TV Boxes
And as equipment is changed from time to time sand more stuff is added I have a sort of block think of 20 addies for each section
If say I bought a new network drive I would note its mac address and look at the list and then allocate the next available Network storage ip against it
Sound s a bit anal but it makes it easier to know where the equipment is on your router
Recently though we had an issue with phones appearing with different local addresses and this is due to an android update that pushes the device to use a randomised MAC
Je vais “essayer” de comprendre!
essayer said:
set all machines to dynamic IP
then program the router to hardcode specific machines (mac addresses) to allocated IPs, say in the 2-128 range, and release the remainder for dynamic IPs (wifi etc)
So in other words set the DHCP range from 129-X?then program the router to hardcode specific machines (mac addresses) to allocated IPs, say in the 2-128 range, and release the remainder for dynamic IPs (wifi etc)
drmotorsport said:
Ransoman said:
Configure the DHCP Pool to a smaller set of addresses e.g. 192.168.1.100-200. Ensure all your static IP's are under 192.168.1.100.
+1This is the simplest approach in a small LAN without a proper DHCP server.
Driller said:
A load of great advice here-thanks gentlemen!
If I may and in no particular order :
1) I have about 40-50 machines on the router.
2) It’s a “pro” version router so I don’t think it’s a bottleneck
3) Do I take it then that my belt and braces approach of putting a static address on a machine AND reserving this same address in the DHCP range on the router is not good?
4) At the moment my DHCP range is 90-150 and within this there are some machines with static IPs.
Wouid it be ok to change the DHCP range to say 151-200? That way I can avoid these static addresses being hijacked by the DHCP on the days they are not turned on, which I think is what may be happening.
Are there any down sides to changing the DHCP range in this way?
2) what router specifically If I may and in no particular order :
1) I have about 40-50 machines on the router.
2) It’s a “pro” version router so I don’t think it’s a bottleneck
3) Do I take it then that my belt and braces approach of putting a static address on a machine AND reserving this same address in the DHCP range on the router is not good?
4) At the moment my DHCP range is 90-150 and within this there are some machines with static IPs.
Wouid it be ok to change the DHCP range to say 151-200? That way I can avoid these static addresses being hijacked by the DHCP on the days they are not turned on, which I think is what may be happening.
Are there any down sides to changing the DHCP range in this way?
3) waste of time
4) yep you can do that, but then you are still managing dhcp reservations and static IP’s on devices, managing spreadsheets, devices and the router, it’s easier to drop the dhcp lease time and manage via reservations.
What’s the background here, domestic of business setting, what’s the impact of the conflicts, how many static IP’s do you expect to manage, what’s the rate of change on static IP’s?
Edit: re read the op so it’s a business setting
Edited by Captain_Morgan on Wednesday 15th June 13:45
Gassing Station | Computers, Gadgets & Stuff | Top of Page | What's New | My Stuff