pointing dhcp server router IP as switch IP
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12-23-2018 05:10 PM - edited 03-08-2019 04:52 PM
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.
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LAN Switching
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12-24-2018 12:47 AM
- The question is invalid.
M.
-- Each morning when I wake up and look into the mirror I always say ' Why am I so brilliant ? '
When the mirror will then always repond to me with ' The only thing that exceeds your brilliance is your beauty! '

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12-24-2018 01:36 AM
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...
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12-24-2018 09:29 AM
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
Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.
Kind Regards
Paul
