pointing dhcp server router IP as switch IP

[Ikenna1992]

Hi everyone, I have a router with two sub interfaces fa0/1.10 IP address 192.168.1.1/24, and fa0/1.20 IP address 192.168.2.1/24. This router is connected to HP layer 3 switch, with vlan10 IP 192.168.1.10/24, and vlan20 IP 192.168.2.10/24. 

The dhcp server is connected to vlan10 IP 192168.1.18, it provides dhcp IP for devices in vlan 10 and 20.

I will like to point the router of this dhcp server to the switch vlan IP address. Is it possible to do that and how can it be done.

[marce1000]

  - The question is invalid.

M.

[Georg Pauwen]

Hello,

not sure if I fullly understand your topology, but typically you would configure an IP helper address on the router interface that is not on the same subnet as the DHCP server. So in your case it would be:

interface FastEthernet0/1.20

ip address 192.168.2.1 255.255.255.0

ip helper-address 192.168.1.x <-- the IP address of the DHCP server

I think on the HP, the command syntax is exactly the same, so on the Vlan 20 interface of the HP, you might need the same configuration...

[paul driver]

Hello

As the Hp switch is performing the inter-vlan routing then the rtr doesn't require to have the sub-interfaces of the switch vlans it just requires a L3 address between the switch and the rtr,

I would also suggest apply the dhcp server service on the switch and not the rtr.

For communication between switch/rtr. the rtr will just require a couple of static routes to point towards the vlans running on the switch.

Example:
rtr:
no int fa0/1.10
no int fa0/1.20

Default interface fa0/1
int fa01
description HP Lan switch
ip address 192.168.100.1 255.255.255.0
no shut

ip route 0.0.0.0 0.0.0.0 x.x.x.x (wan interface)
ip route 192.168.1.0 255.255.255.0 fa0/1 192.168.100.254
ip route 192.168.2.0 255.255.255.0 fa0/1 192.168.100.254

Hp switch
interface vlan-interface 100

ip address 192.168.100.254 255.255.255.0

no shut

int x/x
description link to rtr
port link-type access

port access vlan 100

Ip route 0.0.0.0 0.0.0.0 192.168.100.1

dhcp enable

dhcp server ip-pool Vlan10
network 192.168.10.0 mask 255.255.255.0
domain-name XXXX

dhcp server ip-pool Vlan20
network 192.168.20.0 mask 255.255.255.0
domain-name XXXX

dhcp server forbidden-ip x.x.x.x

int vlan 10
dhcp select server global-pool

int vlan 20
dhcp select server global-pool