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IP-Helper

hunnetvl01
Level 1
Level 1

Hi All,

I have a dhcp server on w2k3 and one scope for one LAN .

I want to have another scope on the same dhcp server for a 2nd Vlan and I did the IP helper and ip broadcast on the 2nd Vlan interface but it is not working.

No PC gets IP in the second scope.

Thaks,

Vlad

27 Replies 27

Ram,

I did the same config you have and nothing.

This is also a lab I am trying on.

I changed the vlan, changed the ip addresses..still the same.

I see the request from the client but no offer from server.I am missing something and I dont know what.

The 2 swithes -- the ' core' and the access are doing VTP and I can ping from server to the client and viceversa.

Thanks,

Vlad

Vlad

Perhaps the issue is not with the switch but the DHCP server itself. What is the default-gateway set to on the DHCP server ?

Jon

Jon,

The default-gateway for the 2nd scope is teh SVI 192.168.100.129/25.

I have changed the IP address and the scope in the DHCP from 172.16.6.0/24 to 192.168.100.128/25.

I have now vlan 7 with 172.20.19.0/24 and

vlan 18 with 192.168.100.128/25.

int vl 18

ip add 192.168.100.129/25

ip helper-add 172.20.19.254

no ip directed-broadcast

I was thinking that the problem in not with the switch also , but I cant get to understand what would the server problem be.

What could be wrong with the server?

The server sits in Vlan 7 and the scope in Vlan 7 works just fine.

Regards,

Vlad

Vlad

I meant the default-gateway on the server under the network configuration ie. is it's default-gateway set to 172.20.19.1 ie. the L3 vlan interface on your switch ?

Jon

Jon

In a previous post Vlad says that a PC with an assigned address in the VLAN can ping the server and the server can ping the PC. If that is true it indicates that it is not an issue with the default gateway on the server.

Vlad

It is helpful to know that the server and the PC can ping each other. This proves that it is not a basic IP connectivity issue that is preventing DHCP from working. You should not expect to see an ARP from the server in wireshark running on the PC. Since the server is in a different subnet, the server will send through its default gateway and will not arp for the PC.

I agree with the suggestion from Jon that the issue may be in the server or in its scope for vlan 60. Can you check the configuration of the scope and let us know its details.

HTH

Rick

HTH

Rick

Rick

Good point, missed that one.

Jon

Rick, Jon-

Dont know if you checked my previous post,but just in case , I ve changed the IP and the vlan so I have now:

vlan 7 & vlan 18

int vl 7

ip add 172.20.19.1

int vl 18

ip add 192.168.100.129

ip help add 172.20.19.254

On the DHCP server( IP 172.20.19.254) I have 1 scope in vlan 7 ( the vlan that the DHCP sits in with default gateway 172.20.19.1) and 1 scope in vlan 18 as :

192.168.100.128

Server and Scope options:

IP excluded: 192.168.100.129

Router 192.168.100.129 and thats all.

With a hardcoded IP I can ping the server and the other way around.

Regards,

Vlad

Vlad,

Try this.

connect another switch2 and create dhcp scope address in SW2 after that check in your pc getting ip address or not .

Regards

Ram

Ram,

I had 3 scopes on the switch that the current DHCP server is connected to and they were working good.

I still have two scopes there -after I removed the scope for vlan 7 and put it on w2k3- and the PCs are getting IP with no problem from those 2 remaining pools.

Does not seem to be a switch issue.

I have even set-up bootp forward on the switch where teh SVI's are.

Regards,

Vlad

Ram,

To be honest , it does not really help.

I have the same thing set-up here.

Regards,

Vlad

Happy New Year all!

I just wanted to inform everybody that I finally found the problem for this and I will share it even if it sounds lame :)

The issue was that the L3 was not forwarding the DHCP relay , cos the "service DHCP" was NOT enabled.....

Anyway,

Thanks to all for help!

Vlad

Vlad

I am glad that you found and corrected the problem. Thank you for posting back to the thread indicating that you had solved the problem and identifying what the problem turned out to be. This will help other people who read about this problem and now can see what the problem was.

HTH

Rick

HTH

Rick
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