multi interfaces(vlans) configuration

Thu Oct 8 14:25:25 UTC 2020

Thanks

The network gear in my sites is the bottleneck
It supports up to 256 DHCP servers/relay agents.
Do you think that raspberry pi could handle 500 VLAN interfaces?

-----Original Message-----
From: dhcp-users <dhcp-users-bounces at lists.isc.org> On Behalf Of Steve van
der Burg
Sent: Thursday, October 8, 2020 3:20 PM
To: Users of ISC DHCP <dhcp-users at lists.isc.org>
Subject: RE: multi interfaces(vlans) configuration

In my case (and in nearly all cases?) the DHCP traffic from the clients on
those VLANs is being forwarded to the DHCP servers by the network gear.  I
don't run ours, but I know that our network people have added "DHCP helper
address" settings to all (checking...) 2530 subnets.  It all arrives on
one interface on each of my DHCP servers.  I can't imagine having 2500
virtual interfaces on either of those.

...Steve

-----Original Message-----
From: dhcp-users <dhcp-users-bounces at lists.isc.org> On Behalf Of Ahiya
Zadok
Sent: Thursday,October 08,2020 8:08 AM
To: Users of ISC DHCP <dhcp-users at lists.isc.org>
Subject: RE: multi interfaces(vlans) configuration

CAUTION: This email originated from outside the organization. Do not click
links or open attachments unless you recognize the sender and know the
content is safe.

Thanks, Steve

Do you think that the numbers of subnets and the number of interfaces
(vlans) that DHCP is listening to have much effect on resource
utilization?

-----Original Message-----
From: dhcp-users <dhcp-users-bounces at lists.isc.org> On Behalf Of Steve van
der Burg
Sent: Thursday, October 8, 2020 3:01 PM
To: Users of ISC DHCP <dhcp-users at lists.isc.org>
Subject: RE: multi interfaces(vlans) configuration

I'm serving leases from a total lease pool that has about a quarter of a
million leasable addresses, with about 30k active leases at any one time.
Most lease lengths are 60 hours (2.5 days) and those are all being served
from a pair of single-CPU virtual machines (running Debian 10) with 2GB
RAM each.  And each one isn't really breaking a sweat.  I rarely see more
than 20% CPU usage and more than 75% of RAM used by dhcpd.

As Glenn said, lease length can make a big difference with regards to
total traffic, CPU load, etc, but with lease lengths like mine you can see
that you don't need much in the way of hardware.

...Steve

-----Original Message-----
From: dhcp-users <dhcp-users-bounces at lists.isc.org> On Behalf Of Ahiya
Zadok
Sent: Thursday,October 08,2020 4:03 AM
To: Users of ISC DHCP <dhcp-users at lists.isc.org>
Subject: RE: multi interfaces(vlans) configuration

CAUTION: This email originated from outside the organization. Do not click
links or open attachments unless you recognize the sender and know the
content is safe.

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.
>
>
>
> --
> Sent from: http://isc-dhcp-users.2343191.n4.nabble.com/
> _______________________________________________
> ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
>
> dhcp-users mailing list
> dhcp-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support
subscriptions. Contact us at https://www.isc.org/contact/ for more
information.

dhcp-users mailing list
dhcp-users at lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support
subscriptions. Contact us at https://www.isc.org/contact/ for more
information.

dhcp-users mailing list
dhcp-users at lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users

This email is directed in confidence solely to the person named above and
may contain confidential, privileged or personal health information.
Please be aware that this email may also be released to members of the
public under Ontario's Freedom of Information and Protection of Privacy
Act if required. Review, distribution, or disclosure of this email by
anyone other than the person(s) for whom it was originally intended is
strictly prohibited. If you are not an intended recipient, please notify
the sender immediately via a return email and destroy all copies of the
original message. Thank you for your cooperation.
_______________________________________________
ISC funds the development of this software with paid support
subscriptions. Contact us at https://www.isc.org/contact/ for more
information.

dhcp-users mailing list
dhcp-users at lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users
_______________________________________________
ISC funds the development of this software with paid support
subscriptions. Contact us at https://www.isc.org/contact/ for more
information.

dhcp-users mailing list
dhcp-users at lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users

This email is directed in confidence solely to the person named above and
may contain confidential, privileged or personal health information.
Please be aware that this email may also be released to members of the
public under Ontario's Freedom of Information and Protection of Privacy
Act if required. Review, distribution, or disclosure of this email by
anyone other than the person(s) for whom it was originally intended is
strictly prohibited. If you are not an intended recipient, please notify
the sender immediately via a return email and destroy all copies of the
original message. Thank you for your cooperation.
_______________________________________________
ISC funds the development of this software with paid support
subscriptions. Contact us at https://www.isc.org/contact/ for more
information.

dhcp-users mailing list
dhcp-users at lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users