VLAN & DHCP server

Glenn Satchell Glenn.Satchell at uniq.com.au
Fri Dec 14 12:41:35 UTC 2007


If you label your host statements like:

   host myhost-vlan2  { hardware ethernet 00:01:02:03:04:05; }


   host myhost        { hardware ethernet 00:01:02:03:04:05;
                        fixed-address 192.168.1.10; }

then it will mostly do what you want, and you don't need the concat bit.

regards,
-glenn

>Date: Thu, 13 Dec 2007 08:04:05 -0800
>From: Alan Hagge <Alan.Hagge at warnerbros.com>
>To: dhcp-users at isc.org
>Subject: Re: VLAN & DHCP server
>
>All true; however the problem that I've run into is when I want to
>assign fixed addresses to one VLAN interface on a host, while allowing
>others to be pulled from a pool.  I attempted to send this to the list
>on a prior occasion, but apparently it never appeared:
>
>-----
>Our network consists of two VLANs, both served by a single DHCP server
>(with direct connections to both VLANs).  Some of our client machines
>are in one VLAN, some in both.  Some need fixed addresses in one or the
>other VLAN, a few need them in both.  Most need only pooled addresses in
>both.  I need to use DDNS to set hostnames for each IP address. How can
>I set this up?
>
>Here's what I've tried.  In one VLAN (the "primary" LAN), the
>ddns-hostname is set to
>
>  subnet 192.168.1.0 netmask 255.255.255.0 {
>    ddns-hostname = host-decl-name;
>    ...
>  }
>
>while in the other VLAN (the "secondary"), I append to the
>host-decl-name to get the name to send to DNS:
>
>  subnet 192.168.2.0 netmask 255.255.255.0 {
>    ddns-hostname = concat(host-decl-name,"-vlan2");
>    ...
>  }
>
>dhcpd won't let me have more than one "host" section with the same
>hostname, so I've tried various options:
>
>   host myhost        { hardware ethernet 00:01:02:03:04:05; }
>
>works, assigns IP addresses (from pools in both subnets) and updates DNS
>with correct hostnames and IP addresses.
>
>  host myhost        { hardware ethernet 00:01:02:03:04:05;
>fixed-address 192.168.1.10; }
>
>doesn't work.  VLAN1 is assigned correctly (myhost->192.168.1.10), VLAN2
>is assigned an IP address from a pool but not given the specified
>hostname in DNS.  Syslog has "dhcpd: data: host_decl_name: not
>available", indicating that it's not using this host line for the
>MAC-address-to-hostname mapping.
>
>  host myhost        { hardware ethernet 00:01:02:03:04:05;
>fixed-address 192.168.2.10; }
>
>doesn't work.  Same as above, but with the VLANs reversed.
>
>  host myhost        { hardware ethernet 00:01:02:03:04:05;
>fixed-address 192.168.1.10, 192.168.2.10; }
>
>works, assigns IP addresses (to specified fixed addresses) and updates
>DNS with correct hostnames and IP addresses.
>
>
>Is there something I'm missing?  Is there some other syntax to use to
>have a single host, with one MAC address, able to be assigned to a
>pooled address in one VLAN and a fixed address in another VLAN?
>
>Thanks in advance...
>
>
>Any advice is appreciated,
>
>Alan
>
>P.S.  Sorry for hijacking the thread...
>
>Tim Peiffer wrote:
>> This is a frequently asked question that could have been researched
>> before asking.   The first URI I would recommend is a search engine:  
>...
>>
>> Suhaime Raeze wrote:
>>> Im new at configuring dhcp server for vlan. I tried to find sources
>>> from the net and there are various ways which i admit is too
>>> complicated or i couldnt comprehend the instructions.
>> ...
>
>


More information about the dhcp-users mailing list