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Today's Topics:
1. Re: DHCP server configuration does not work for all clients
(Niall O'Reilly)
2. Re: multi interfaces(vlans) configuration
(glenn.satch...@uniq.com.au)
3. Re: multi interfaces(vlans) configuration
(glenn.satch...@uniq.com.au)
----------------------------------------------------------------------
Message: 1
Date: Thu, 08 Oct 2020 23:09:18 +0100
From: "Niall O'Reilly" <niall.orei...@ucd.ie>
To: "Users of ISC DHCP" <dhcp-users@lists.isc.org>
Subject: Re: DHCP server configuration does not work for all clients
Message-ID: <4a639be6-d1fb-4f1a-ad9a-fae8a0e96...@ucd.ie>
Content-Type: text/plain; charset="utf-8"; Format="flowed"
On 8 Oct 2020, at 21:55, Jim Yang wrote:
> `class ?mytest? {`
> ????????? match option dhcp-client-identifier;
> }
Since your packet-capture doesn't show any option 61 (client id) data,
I would expect the hardware address to be used instead, and
would share your expectation of the behaviour.
We must both be overlooking the same thing.
> It seems that I should change the class definition to match either
> option dhcp-client-identifier or hardware.
>
> `class ?mytest? {`
> match pick-first-value (option dhcp-client-identifier,
> hardware);
> }
Or even (since you seem to be specifically interested in using the MAC
address)
class "mytest" { match hardware; }
which would protect against failing to recognize a client with `"Niall's
Mac"`
as the client id, but would potentially introduce the "docking-station"
problem
mentioned in _Droms and Lemon_.
I'm out of ideas. I hope someone else can contribute the missing
insight.
Niall
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Message: 2
Date: Fri, 09 Oct 2020 10:15:10 +1100
From: glenn.satch...@uniq.com.au
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: multi interfaces(vlans) configuration
Message-ID: <8dc731cf584af4c4f0ad451f883a9...@uniq.com.au>
Content-Type: text/plain; charset=US-ASCII; format=flowed
If you have a router forwarding packets between subnets, then the dhcp
server only has to be connected to a single vlan - the router can
forward dhcp broadcasts to the server. So you don't need 500 interfaces
on your dhcp server.
regards,
-glenn
On 2020-10-08 23:07, Ahiya Zadok wrote:
> 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-boun...@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@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-boun...@lists.isc.org> On Behalf Of Ahiya
> Zadok
> Sent: Thursday,October 08,2020 4:03 AM
> To: Users of ISC DHCP <dhcp-users@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-boun...@lists.isc.org> On Behalf Of
> glenn.satch...@uniq.com.au
> Sent: Thursday, October 8, 2020 10:54 AM
> To: Users of ISC DHCP <dhcp-users@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@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
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> ISC funds the development of this software with paid support
> subscriptions. Contact us at https://www.isc.org/contact/ for more
> information.
>
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> notify
> the sender immediately via a return email and destroy all copies of the
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------------------------------
Message: 3
Date: Fri, 09 Oct 2020 10:27:19 +1100
From: glenn.satch...@uniq.com.au
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: multi interfaces(vlans) configuration
Message-ID: <6e62d5decafb476456dca27eed6e8...@uniq.com.au>
Content-Type: text/plain; charset=US-ASCII; format=flowed
ISC dhcpd needs to access the raw ethernet interface, so doesn't play
well with vlan sub-interfaces.
You don't have 256 different dhcp servers, only one. Typically in the
router each interface definition will include a dhcp relay or
ip-forwarder, and this will always be the same the single IP address of
your dhcp server.
If that doesn't work you may be able to set the dhcp relay in your
switches as an alternative.
regards,
Glenn
On 2020-10-09 01:25, Ahiya Zadok wrote:
> 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-boun...@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@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-boun...@lists.isc.org> On Behalf Of Ahiya
> Zadok
> Sent: Thursday,October 08,2020 8:08 AM
> To: Users of ISC DHCP <dhcp-users@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-boun...@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@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-boun...@lists.isc.org> On Behalf Of Ahiya
> Zadok
> Sent: Thursday,October 08,2020 4:03 AM
> To: Users of ISC DHCP <dhcp-users@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-boun...@lists.isc.org> On Behalf Of
> glenn.satch...@uniq.com.au
> Sent: Thursday, October 8, 2020 10:54 AM
> To: Users of ISC DHCP <dhcp-users@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@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@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@lists.isc.org
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>
> This email is directed in confidence solely to the person named above
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