Configuring DHCP IP Helper Address, Packet Tracer v. 7.2

download packet tracer's source files:

A DHCP client is an internet host using DHCP to obtain configuration parameters such as an IP address, A DHCP relay agent is any host that forwards DHCP packets between clients and servers, Relay agents are used to forward requests and replies between clients and servers when they are not on the same subnet.
In this topology diagram, we will configure Router1 as the DHCP server for the HR and the Sales departments, I will configure two address pools one for Sales with the network of 192.168.1.0 /24 and the HR with the network of 172.16.1.0/24
On Router1
# ip dhcp excluded-address 192.168.1.1 192.168.1.10
# ip dhcp pool Sales
# network 192.168.1.0 255.255.255.0
# default-router 192.168.1.1
# dns-server 8.8.8.8
Now after we are done with the Sales network, let us configure the dhcp for the HR department.
# ip dhcp excluded-address 172.16.1.1 172.16.1.10
# ip dhcp pool HR
# network 172.16.1.0 255.255.255.0
# default-router 172.16.1.1
# dns-server 8.8.8.8
Now, because the DHCP server is in a different subnet, we will configure Router2 as the IP helper-address
On Router2
# int g0/1
# ip helper-address 10.1.1.1
Now we want to route the traffic between the two network, so we will configure static route on Router1 and on Router2.
On Router1
# ip router 172.16.1.0 255.255.255.0 10.1.1.2
On Router 2
# ip route 192.168.1.0 255.255.255.0 10.1.1.1
On the PCs on both networks, let us allow the PCs to automatically get their IP address configurations but choosing the DHCP button.

This is how to configure the IP helper-address.

[maxmateria]

Perfectly Clear Instruction, Kudos Saleh

[legendaryphoenix]

You have no idea on how big of a help this lesson is to me. I have cracked my skull trying to find a solution to why my DHCP request failed in another subnet from the subnet that contains the DHCP server, despite providing the IP helper-address.

Now I know that I need to configure the static routing between the networks. And you showed me how to do it with great detail and precision.

Thank you ❤😊

[Corswain]

Thank you for this!
All I wanted to know if we could use the ip helper-address command on cisco routers when the DHCP server was also a cisco router, and I also wasn't sure exactly what address to specify on the neighbouring routers. I found plenty of other information out there on configuring dhcp relay with that command, but all the examples were using an actual DHCP server (not a router) which had a single static IP address. So in those cases it was easy to work out what ip to put after the ip helper-address command.
But in my case I have a router being the dhcp server, connected to 2 other routers on either side, and 6 separate subnets to give dhcp to. It wasn't immediately clear to me what IP to specify when the dhcp router has multiple interfaces to various networks, and which interfaces to use the commands on.
Your explanation really cleared all of that up for me and showed it is possible, so thank you!!
Got my lab working too all green lights and DHCP working!

[mikkio]

thanks alot static ip route was all i needed for complete 3 days util i came across your video for solution. thanks

[EngSharafARoble]

thank you so much Saleh. i was so confused about ip helper command. but now am like "Ask me anything about ip helper" heheheh. thank you man

[OutMagic]

Helped me greatly mate! Awesome straight forward explanation thank you :)

[RashidKhan-iqmy]

Thanks, this is what i was looking for.

[tesfayeguta]

Thank you; that's brief and clear.

[engyale]

Thanks brother it's nice of you doing this!

[ferenccziryek]

hi
how can use ip helper-address for same dhcp and vlan on different router? I tried but not working. can I get help?

[matricksengineers]

I have 7 Vlans in my network, all they use DHCP, in last two years they were all working well, but nowdays in one Vlan, some connected computers get valid ip addresses automatically others get invalid IP address and it require me to assign a static IP address, how can I solve that issue, inorder to make all the connected computers get valid ip addresses automatically?

[frikeyerson]

I have it clearer now, but I've got another queston, what would happen if there were several routers? I mean, 3 instead of 2, should I keep using the IP helper address commando with next hop too?
Please respond, I am confused.

[dietalkaa]

stop saying "they are in the same subnet" Instead use they are in the same BROADCAST DOMAIN!!!!