one DHCPD server multi subnets
tangaish.en
tangaishien at gmail.com
Thu Nov 1 08:38:20 UTC 2007
hi, dhcp-users
so I modified my conf file as below:
subnet 172.16.1.0 netmask 255.255.255.0 {
}
subnet 172.16.5.0 netmask 255.255.255.0 {
pool {
range 172.16.5.210 172.16.5.220;
option routers 172.16.5.254;
option subnet-mask 255.255.255.0;
}
}
subnet 172.16.4.0 netmask 255.255.255.0 {
pool {
range 172.16.4.210 172.16.4.220;
option routers 172.16.4.254;
option subnet-mask 255.255.255.0;
}
}
dhcpd service restart without problem, in fact I don't need pool
function too, I deleted pool {} and conf look like this:
subnet 172.16.4.0 netmask 255.255.255.0 {
range 172.16.4.210 172.16.4.220;
option routers 172.16.4.254;
option subnet-mask 255.255.255.0;
}
dhcpd restart ok, I believe the server should work for my network, I'll
test it later. thanks.
and I think the reply should add in dhcpd document as a relay or remote
dhcp section, it's helpful.
Simon Hobson wrote:
> tangaish.en wrote:
>
>> now my conf file look like this:
>>
>> ddns-update-style interim;
>> ignore client-updates;
>>
>> subnet 172.16.0.0 netmask 255.255.0.0 {
>>
>> # --- default gateway
>>
>> option domain-name "guest.XXX.com";
>> option domain-name-servers 172.16.1.2,172.16.1.4;
>>
>> option netbios-name-servers 172.16.1.4;
>> default-lease-time 21600;
>> max-lease-time 43200;
>>
>> pool {
>> range 172.16.5.210 172.16.5.220;
>> option routers 172.16.5.1; option
>> subnet-mask 255.255.255.0;
>> }
>>
>> pool {
>> range 172.16.4.210 172.16.4.220;
>> option routers 172.16.4.1; option
>> subnet-mask 255.255.255.0;
>> }
>> }
>>
>> I can't test it because of the 3-layer switch offer dhpc function
>> and PCs need it every work day, I must wait weekend to try isc dhcp
>> and switch relay.
>>
>> I think this conf file don't work.
>
>
> Correct, it won't work. You need a subnet declaration for each subnet,
> and inside that a pool declaration for the addresses in that subnet
> which are to be dynamically assigned. Every subnet declaration must
> match exactly (address & mask) the real subnets. Something like this,
> note global options at the start which are outside the subnet
> declaration.
>
> option domain-name "guest.XXX.com";
> option domain-name-servers 172.16.1.2,172.16.1.4;
>
> option netbios-name-servers 172.16.1.4;
> default-lease-time 21600;
> max-lease-time 43200;
>
>
> subnet 172.16.1.0 netmask 255.255.255.0 {
> option routers 172.16.1.1;
> option subnet-mask 255.255.255.0;
> pool {
> range 172.16.1.210 172.16.1.220;
> }
> }
>
> subnet 172.16.2.0 netmask 255.255.255.0 {
> option routers 172.16.2.1;
> option subnet-mask 255.255.255.0;
> pool {
> range 172.16.2.210 172.16.2.220;
> }
> }
>
> ...
>
> subnet 172.16.5.0 netmask 255.255.255.0 {
> option routers 172.16.5.1;
> option subnet-mask 255.255.255.0;
> pool {
> range 172.16.5.210 172.16.5.220;
> }
> }
>
>
>> I want to know dhcpd run with this conf file can do it or not? if yes
>> I'm intersting in figure out how isc dhcpd know which dhcprequest is
>> coming from that net, is there a relay address in dhcprequest package
>> and dhcpd assign address base on that address?
>
>
> Once you configure DHCP to match teh subnets available, the server
> automatically works out which subnet a client belongs to. For clients
> on a local network, it is done simply by which physical interface the
> request arrives on.
>
> For clients on remote subnets, the bootp-helper is the key - it
> receives the broadcast from the client, fills in it's own address on
> that network (in the GIAddr (Gateway Interface Address) field), and
> then forwards it to the server. The server then uses the GIAddr to
> figure out the correct subnet.
>
>
> So you as the admin need do nothing (apart from correctly defining the
> subnets) to make this work - it's just happens automagically.
>
>
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