DHCP Relay in Cisco Packet Tracer

[aiden21c]

Hi all, Im a beginner to CPT and i am hoping someone can assist me for an assignment coming up.

I am having trouble configuring a DHCP relay from a DHCP server to a network consisting of multiple routers, with their devices on their own networks. The three main issues I am having are:

1. When one of the networks connected directly to the server has DHCP configured, the other network looses connection and can o longer reach the server. These two networks are outlined in blue in the png attached
2. I am unsure whether or not there is a way to chain DHCP relays between routers, in which the connection is as follows: DHCP server -> router/network 1 -> router/network 2. I have been unable to configure DHCP in this second network when attempting to relay between multiple routers.
3. I have a broken connection (red in the png) attempting to connect the two networks as outlines in q2. I am unsure where this is wrong.

I have attached both the .pkt and .png files. Any help would be greatly appreciated as I have struggled to find help for this anywhere. Cheers

[Georg Pauwen · Accepted solution]

Hello,

the helper addresses go on the LAN interfaces. I corrected a lot of wrong IP addressing, find attached the working file.

[aiden21c]

Thank you so much for your help. I have spent the morning attempting to copy your configuration changes but no matter what ive tried, i just cant seem to get PC4 to obtain IP through DHCP. I played around with the network you made and it works perfectly i just cant seem to figure out what ive done wrong when implementing it myself.

The connection between Router5 and its switch also confused me, as im not to sure what IP to configure fa1/0 to. I would also assume there would be further steps (ip helper configurations) to send DHCP requests from Router1 to Router5 and then to PC5.

If you could provide further assistance I would greatly appreciate it but youve helped me more than enough already. Thanks heaps.

[Keith6783]

The DHCP server doesn't have a route to 192.168.3.0/24, so when DHCP relay is used on R4, the source IP will be coming from the address 192.168.3.1, which the sever can't reach.    If you change the default gateway on the server to 192.168.2.2  (R4 fa0/0 address) that is one solution.

Best wishes.

[121795814]

hi.  I find some problems.

1 no conection, because 1000M fiber port  and 100M fiber dont speed success,attempt same card port .

2 192.168.2.1 address duplicated on the Router0 and Router2 

3 router3 didnt go to 192.168.2.254 for routing ， router0 didnt go to pc3 for routing。

Detailed configuration can be viewed in the attachment

[guruvignesh]

Hello aiden21c,

provide general guidance on setting up DHCP relay in a network with multiple routers. DHCP relay allows DHCP requests from clients to be forwarded to a DHCP server.

1. DHCP Relay Configuration on Routers:

   Each router that needs to relay DHCP requests should be configured accordingly. Typically, this involves setting up the DHCP relay agent on the interface that faces the client network.

2. Chaining DHCP Relays:

   You can chain DHCP relays by configuring each router to relay DHCP requests to the next router in line, ultimately reaching the DHCP server.

3. Routing and Connectivity:

   Ensure that the routers are properly configured to route traffic between networks. Check routing tables to ensure that the necessary routes are in place.

Here's a step-by-step guide:

• On each router:

  • Configure the interface facing the client network with the ip helper-address command, specifying the IP address of the DHCP server.
  • Ensure routing is correctly set up to forward DHCP requests to the next-hop router or directly to the DHCP server.

• Verify that each client network can reach the DHCP server.