ā11-21-2012 01:26 AM - last edited on ā03-25-2019 04:22 PM by ciscomoderator
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
ā11-21-2012 01:35 AM
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
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ā11-21-2012 02:46 AM
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?
ā11-21-2012 03:21 AM
Hi,
yes without this command the router can't be a DHCP relay agent. Good catch
Regards.
Alain
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