Multi-subnet/vlan and failover

[Kyle Johnson]

Are you looking for something like this?

subnet 172.21.27.0 netmask 255.255.255.0 {
  option subnet-mask 255.255.255.0;
  option broadcast-address 172.21.27.255;
  option routers 172.21.27.1;
  ddns-domainname "example.com.";
  option domain-search "example.com";
  pool {
    failover peer "dhcp-failover";
    range 172.21.27.5 172.21.27.254;
  }
}


On Thu, May 9, 2013 at 8:08 PM, Gregory Sloop <gregs at sloop.net> wrote:

> So, I've done a fair bit of reading and searching - and this general
> template is what I thought would work, but it doesn't.
>
> Let me post the dhcp.conf file and then discuss what's wrong and ask
> for pointers.
>
> ---
> authoritative;
> #ddns-update-style interim;
> ignore client-updates;
> #option host-name = config-option server.ddns-hostname;
>
> #include "/etc/rndc.key";
>
> option domain-name              "somedom.local";
> option domain-name-servers      10.1.1.190,10.1.2.1,10.1.1.17;
> option time-offset              -18000; # Pacific Standard Time
> option ntp-servers              10.1.1.14
> one-lease-per-client off;
>
> #4 hour lease
> default-lease-time 14400;
> max-lease-time 14400;
> option ip-forwarding off;
>
> failover peer "dhcp-failover" {
>   primary; # declare this to be the primary server
>   # Address if THIS dhcp server, or what address to listen ON
>   address 10.1.1.1;
>   port 647;
>   # Address of the DHCP fail-over peer.
>   peer address 10.1.1.2;
>   peer port 647;
>   max-response-delay 60;
>   max-unacked-updates 10;
>   #load balance max seconds 3;
>   mclt 3600;
>   split 0;
> }
>
>     subnet 10.1.1.0 netmask 255.255.255.0 {
>         range 10.1.1.1 10.1.1.254;
>         option routers                  10.1.1.1;
>         option subnet-mask              255.255.255.0;
>         failover peer "dhcp-failover";
>     }
>
>     subnet 10.1.2.0 netmask 255.255.255.0 {
>         range 10.1.2.1 10.1.2.254;
>         option routers                  10.1.2.1;
>         option subnet-mask              255.255.255.0;
>         failover peer "dhcp-failover";
>     }
>
>     subnet 10.1.3.0 netmask 255.255.255.0 {
>         range 10.1.3.1 10.1.3.254;
>         option routers                  10.1.3.1;
>         option subnet-mask              255.255.255.0;
>         failover peer "dhcp-failover";
>     }
>
> ---
> Now, I've disabled DDNS updates for simplicity sake. Once I get the
> multi-subnet/VLAN setup and failover working I'll add that back.
>
> Perhaps that impacts things somehow, so if you'll keep that in mind,
> I'd appreciate it.
>
> So, when I try this config I get an error saying that a failover needs
> to be inside a shared network block.
>
> But if I do that, I've been told [read] that the DHCP server won't
> know how to assign the different subnets. [This would apply to a
> network where I wanted to share all the 10.1.1.1-10.1.3.254 as a
> single pool/block and assign any station any IP in the whole block.]
>
> But I have a L3 switch and I want these assigned to each VLAN.
>
> ---
> So, I setup the conf file without a shared-network and it works fine
> with the L3 DHCP helper/proxy. Clients on VLAN1 get 10.1.1.0 blocks
> and VLAN2 get 10.1.2.0 blocks etc.
>
> So, with the "failover" block commented out, it works charmingly! Very
> cool!
>
> ---
> But I *also* want to use failover.
>
> And when I put in a fail-over outside a shared-network, it complains
> that it must be inside a shared network.
>
> So, how to I use fail-over AND maintain the subnet grouping above?
>
> ---
> I'll keep reading, but I've tinkered with this quite a bit and for the
> life of me, I can't see how one would go about it.
>
> -Greg
>
>
>
>
> --
> Gregory Sloop, Principal: Sloop Network & Computer Consulting
> 503.251.0452 x121 Voice | 503.251.0452 Fax
> www.sloop.net
> mailto:gregs at sloop.net
>
> _______________________________________________
> dhcp-users mailing list
> dhcp-users at lists.isc.org
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>
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