multi interfaces(vlans) configuration

[Ahiya Zadok]

Thanks, Glenn

Regarding the number of sites- I plan to have a server per site.
Each site will have around 500 subnets with around 10-15 devices per
subnet.
Does the number of IPs per subnet affect memory even when they are not
assigned?
This is MDUs installation so 24H lease is good enough.


-----Original Message-----
From: dhcp-users <dhcp-users-bounces at lists.isc.org> On Behalf Of
glenn.satchell at uniq.com.au
Sent: Thursday, October 8, 2020 10:54 AM
To: Users of ISC DHCP <dhcp-users at lists.isc.org>
Subject: Re: multi interfaces(vlans) configuration

Hi,

The size of the server depends on two things - the number of clients and
how often they renew their lease.

Eg if they renew once every hour versus once every day then that takes
24 times as much cpu reources in the work done to renew the leases and
record the updates.

Secondly a large amount of the lease data is kept in memory, so the number
of lease affects the memory size.

So, how many sites? You say 500 vlans - which I guess equates to subnets
- that's what dhcpd configuration needs. And how many devices per subnet
typically? A subnet doesn't have to be a /24, it can be any size that is
suitable for that subnet, eg multiple /24 pools, /21 will give 2048
addresses, /20 will give 4096, or bigger if needed.

Others running large number of clients, say 10-20k can probably offer
better advice, but I don't think a PI4 with 8GB is not going to have
enough memory, cpu or storage I/O.

You'll probably want a server with 32 or 64GB memory and SSD or NVME disks
for high throughput. With that many clients then 10 or 25 Gigabit network
is probably needed too.

You'll also need to think about what bandwidth you have in your back-haul
networks back to the central network where the dhcp server is.

However, a PI4 is cheap so you could try one out to see how it goes.

regards,
-glenn

On 2020-10-08 15:57, ahiya wrote:
> I'm new to isc/kea.I have multi-sites with around 2000-5000 devices
> per site.the real issue is that they are spread across 500 different
> VLANs.I wanted to know is isc/kea is the right solution for that
> task.and what is the right way to implement it?if the only service I
> need is dhcp4 serving all these segments, what will be the HW
> requirements for this task?
> Raspberry PI4 with 8G mem will be enough?should I use .conf files or
> should I go for the backend server?ill appreciate any feedback.thanks
> a lot.
>
>
>
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