Spark Smart Modem 1 & 2 - Limits on number of DHCP address reservations

Forums › Spark New Zealand (including Skinny and BigPipe) › Spark Smart Modem 1 & 2 - Limits on number of DHCP address reservations

irs

4 posts

Wannabe Geek

#296197 29-May-2022 11:14

With regards to Spark Smart Modems 1 or 2, and deploying IP addresses based on the devices MAC address in the range I allocate for DHCP. (i.e. DHCP reservation addresses)...

Does anyone know the limit to the number of devices that can be served up with static addresses?

FYI: I tried doing this on a Huawei HG253 modem and found it was limited to eight devices. I am planning to have 60 to 70 devices.

thanks, Ian.

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4 posts

Wannabe Geek

#2920089 29-May-2022 18:46

Just visited a friends place and they have a Spark Smart Modem 1 (Arcadyan VRV9517-UWAC34-A-SP).

I logged into admin account and found that LAN -> LAN DHCP -> has in the title "up to 10 computers".

So that doesn't fit my plans.

Any chance anyone knows the limit for the Spark Smart Modem 2?

thanks, Ian.

Gordy7

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#2920159 29-May-2022 21:21

Throwing my 2 cents worth into the thread....

You might be lucky to find a router that can handle 60 or 70 DHCP reservations.

Maybe you could use IPv6? However, if you are on Spark using a SM2 then maybe not... Spark does not use IPv6 🤥

An IPv6 device will use the MAC address of its interface to generate a unique 64-bit interface ID. However, a MAC address is 48 bit and the interface ID is 64 bit.

https://networklessons.com/ipv6/ipv6-eui-64-explained

Gordy

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cbrpilot

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Spark NZ

#2920238 29-May-2022 23:05

Smart Modem 1 looks like it does 10 addresses today. I'm confident that will expand in the future - but not to the 60-70 range. I don't have a date for that change.

I am not sure about the Smart Modem 2 (I don't have one). Best guess is that it will match the existing Smart Modem 1.

So I don't think the Spark Smart modems will meet your requirements.

My views are my own, and may not necessarily represent those of my employer.

MadEngineer

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#2920242 29-May-2022 23:38

irs:

FYI: I tried doing this on a Huawei HG253 modem and found it was limited to eight devices. I am planning to have 60 to 70 devices.

You're not on Atlantis anymore, Duncan Idaho.

fe31nz

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#2920245 30-May-2022 00:07

My EdgeRouter ERL and ER4 routers have no DHCP limits. They just build a table in RAM and eventually you would run out of RAM, but that would be a massive table. They use standard Linux DHCP server software. I expect that there are a number of routers out there that also use the standard Linux DHCP servers. Anything running a version of OpenWRT will be using Linux DHCP servers software. I am fairly sure that Mikrotik routers will have full featured DHCP also. It is just routers that target the home users only that will be doing utterly stupid things like limiting the number of DHCP entries.

shk292

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#2920276 30-May-2022 08:12

This is the text from the embedded help screen for the SM2:

DHCP Server (IP Address Pool)
The DHCP server function makes setting up a network very easy by assigning IP addresses to each computer on the network. The DHCP Server can be turned off if necessary. Turning off the DHCP server will require you to manually set a Static IP address in each computer on your network. The IP pool is the range of IP addresses set aside for dynamic assignment to the computers on your network. The default is 1-200 (200 computers) if you want to change this number, you can by entering a new starting and ending IP address and clicking on "Save settings".

It looks like you can set any address you like for start and end of DHCP pool. I have mine set as .64 to .253 and that works OK

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xpd

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#2920278 30-May-2022 08:21

Agree with MadEngineer ..... if you want something handling that many devices, a consumer aimed unit is probably not the ideal device.

I have probably about 15-20 devices connecting to my FritzBox no issue. And we're a fairly "tech" family (all 4 of us have at least 2 devices, along with consoles, server, NAS etc)

60-70 - what are you doing ? :D Can only assume in a large flat situation or an office.....

XPD / Gavin

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#2920284 30-May-2022 08:44

Hi as per the other responses, your using the wrong device, I would recommend a mikrotik, fortigate or similar, depending on your network skills you may need to employ help in setting those up to ensure they work correctly and securely.

Cyril

Gordy7

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#2920286 30-May-2022 08:48

The OP is trying to assign an DHCP IP address reservations based on a device/computer hardware MAC address.

This is different to assigning a general DHCP IP address. General DHCP IP addresses are assigned on a first come basis.

I don't have a SM2.... below is a snip from my SM1 which may help:

Gordy

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shk292

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#2920287 30-May-2022 08:55

I misunderstood the question - the SM2 (mine is a Skinny but I think they're the same) has the same limitation as the SM1 posted just above

openmedia

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#2920289 30-May-2022 09:03

cbrpilot:

Smart Modem 1 looks like it does 10 addresses today. I'm confident that will expand in the future - but not to the 60-70 range. I don't have a date for that change.

I am not sure about the Smart Modem 2 (I don't have one). Best guess is that it will match the existing Smart Modem 1.

So I don't think the Spark Smart modems will meet your requirements.

10 is ridiculous. Even just a combination of phones + laptops will exceed that in many houses without addind smart TVs and perhaps some IOT devices.

I've currently got 105 (IPV4) devices allocated on my R7000 router and I'm only just starting to build up my smart environment.

Generally known online as OpenMedia, now working for Red Hat APAC as a Technology Evangelist and Portfolio Architect. Still playing with MythTV and digital media on the side.

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Nate001

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#2920291 30-May-2022 09:07

In all seriousness, why do you need 60-70 static DHCP?

irs

4 posts

Wannabe Geek

#2920313 30-May-2022 10:49

Hi Everyone,

Many thanks for your comments. It sounds like SM1 or SM2 won't meet my requirements and thanks for listing some alternative routers that should.

I'll walk the aisles of PB Tech and survey their router offerings, but in the meantime I might experiment with a quad core 3GHz x86 box with two 1Gb/s ethernet ports running OpenWrt.

https://openwrt.org/docs/guide-user/installation/openwrt_x86

This should have enough grunt to process the PPPoE on the 900/500 WAN link to Spark, and give me plenty of static leases ...although it seems that some folks do have trouble getting more than 50...

https://forum.openwrt.org/t/need-to-increase-50-static-dhcp-lease-limit/27209

Fortunately, I'm not paying the power bill. ...but at least it should take the chill off the room on winter mornings.

cheers, Ian.

kobiak

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#2920315 30-May-2022 11:00

I've got SM1 + pihole on raspberry pi doing DHCP static and dynamic (total 50+ devices). works without issues for past 4+ years. I dont think there's any limit on DHCP using pihole.

helping others at evgenyk.nz

irs

4 posts

Wannabe Geek

#2920317 30-May-2022 11:06

Nate001:

In all seriousness, why do you need 60-70 static DHCP?

My rational is that I want all 70 x devices to have the identical image of their operating system and applications on their SSD. That way if a SDD fails I replace it with a new SSD which has been prepared with the image already copied to it.

As the static leases will assign the IP addresses, then I will know which device I'm SSHing into.

Occasionally I'll need to swap out a whole device and the replacement device will have a different MAC address, but all I need to do is update the DHCP script in the router with the new MAC address.

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