helper-address issue?

[Mephista29]

Hi All

I have an issue with the helper-address on our router 887M IOS c880data-universalk9-mz.150-1.M7.bin.

I configured under a vlan the  helper-address to their DHCP server but it looks like their aren't receiving any request which means when they connect their wifi, they don't get allocated Ips..

The config is as per below :

interface FastEthernet0

switchport access vlan 10

switchport trunk native vlan 10

!

interface Vlan10

ip address 172.30.104.1 255.255.254.0

!

interface FastEthernet2

switchport access vlan 30

no cdp enable

!

interface Vlan30

ip address 10.190.108.1 255.255.255.0

ip helper-address 172.30.104.2

!

Unfortunately there no a lot of tests I am aware I can do from the router:(

1/

#sh ip helper-address vlan 30

Interface                  Helper-Address  VPN VRG Name             VRG State

Vlan30                     172.30.104.2    0   None                 Unknown

2/

#ping 172.30.104.2 sour vlan 30

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.30.104.2, timeout is 2 seconds:
Packet sent with a source address of 10.190.108.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

Now the customer is having a switch which could be where the issue is hiding?

But coudl it be also an IOS bug?

On his DHCP server he is not receiving anything which I find it weird?

Any help, suggestion to troubleshoot that issue is more than welcome!!!

Cheers

Mel

[cadet alain]

Hi,

what is their DHCP server? Is there DHCP snooping or any filtering on the switch or DHCP server ?

You can also sniff with wireshark on a client to see if it gets any offer and ask for the logs on the server.

Regards.

Alain

Don't forget to rate helpful posts.

[Mephista29]

   Thanks Alain for your reply        

humm I just added service dhcp and I can see the dhcp request now

lient's VPN is .

Nov 21 10:38:29: DHCPD: setting giaddr to 10.190.108.1.

Nov 21 10:38:29: DHCPD: BOOTREQUEST from 88e0.f318.0092 forwarded to 172.30.104.2.

Nov 21 10:38:29: DHCPD: client's VPN is .

Nov 21 10:38:29: DHCPD: forwarding BOOTREPLY to client 88e0.f318.0092.

Nov 21 10:38:29: DHCPD: creating ARP entry (10.190.108.10, 88e0.f318.0092, vrf default).

Nov 21 10:38:29: DHCPD: unicasting BOOTREPLY to client 88e0.f318.0092 (10.190.108.10).

Nov 21 10:39:29: DHCPD: client's VPN is .

Nov 21 10:39:29: DHCPD: setting giaddr to 10.190.108.1.

I am still running some debug to make sure it is working but basically could have been the no service dhcp bringing the ip helper address to not work?

[cadet alain]

Hi,

yes without this command the router can't be a DHCP relay agent. Good catch 

Regards.

Alain

Don't forget to rate helpful posts.