DHCP server does not respond to the DISCOVER message it receives from relay agent

[DennisJo82861]

Hi,

I am attempting to make a topology where a router acts as a DHCP relay agent to the DHCP server on another subnet as part of a university course on GNS3. I have looked at the traffic on the link between the DHCP relay router and DHCP server and can see that the DHCP Discover is reaching the server, yet no response is set back. 

Cisco C3660

R1 (DHCP Server)- Config:

int f0/0 :

> ip add 192.168.1.1 255.255.255.0

> no shut

DNS config:

> ip dhcp excluded-address 192.168.20.1 192.168.20.2

> ip dhcp pool SUB20

> network 192.168.20.0 255.255.255.0

> default-router 192.168.20.1

and R2 (DHCP Relay agent)

int f0/1: 

> ip add 192.168.1.2  255.255.255.0

> no shut

int f0/0:

> Ip add 192.168.20.1  255.255.255.0

> ip helper-address 192.168.1.1

> no shut

Yet after configuring it like this, on attempting to assign an IP using DHCP from the connected PC, it fails. Am I missing something? 

[balaji.bandi · Accepted solution]

quick question - do you have route back for the network 192.168.20.0/24 towards  192.168.1.2 (on R1)

[paul driver · Accepted solution]

Hello

Agree with @balaji.bandi RTR1 needs to know how to reach for RTR2 192.168.20.x networ.

RTR1
ip route 192.168.20.0 255.255.255.0 fa0/0 192.168.1.2

RTR2
ip route 0.0.0.0 0.0.0.0 fa0/0 192.168.1.1

[DennisJo82861]

I did not configure that at the time, works fine now. Thank you, Paul!

[DennisJo82861]

Ah alright. I did not configure that, works fine now. Thank you!

[Georg Pauwen]

Hello,

post the full configs of both routers.