06-27-2010 07:57 AM - edited 03-06-2019 11:46 AM
Hi all,
Last week a router was connected to our LAN. The router belongs to a 'mobile' class solution.
This router has DHCP server configured at its local side and dhcp client toward its LAN side.
The next day we were in big trouble. Not one client on the LAN could connect.
Shortly afterwards it was discovered that the default gateway in all the scopes configured on a MS DHCP server.
The strange thing, to me, was that I got several dhcp-snooping messages (SNMP) from a switch
on which I had configured with dhcp-snooping. Unauthorized server !!
I was surprised because was the message contaned the ip-address from the router but later on the
message contained zero's.
Furthermore strange because the router only has dhcp server configured for its inside.
Has anyone the same problem or is known with this issue.
How can I resolve it if it is a Cisco related problem?
Thanx
Jaap
06-28-2010 03:15 AM
May be DHCP relay agent was setup on the routers WAN?!
06-28-2010 04:04 AM
What was the IP your clients were getting? Was it from the router DHCP pool?
What was error you got on the switch on with dhcp-snooping was enabled?
06-28-2010 11:40 PM
Hi,
The IP-addresses came from the dhcp-pool as configured in the router.
No dhcp-relay configured (see attachment).
The warning on the switch with dhcp-snooping enabled gave the message that
an unauthorized dhcp server was signaled (on a trusted interface, the up-link).
On the MS DHCP server (from the logging I got from the quys over there):
DNS renew request from the 10.47.94.0, so from the netword address of the subnet !!
Update failes.
Several renew requests and failures.
???
Greetz Jaap
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