From: Greg Wendel (gwendel@gmail.com)
Date: Wed Nov 28 2007 - 03:18:56 ART
Yes Shekhar,
The DHCP server was seeing the wrong subnet. Unfortunately I cannot
reproduce this at the moment due to hardware issues, but the logs on the
DHCP server definitely saw the wrong subnet The interesting thing was that
the subnet the DHCP server saw didn't match any of the subnets in the
diagram.
Thanks,
On Nov 28, 2007 1:14 AM, <v.shekhar@yahoo.com> wrote:
> Greg,
> I assume that you are saying that the DHCP server is seeing the request
> coming from another subnet rather than 10.10.50.0/24.
> Can u put a sniffer and see whats in the DHCP request hitting the DHCP?
>
>
> Thanks,
> -sHekHar.
> CCIE#17589/CISSP/RHCE.
>
> ----- Original Message ----
> From: Greg Wendel <gwendel@gmail.com>
> To: Cisco certification <ccielab@groupstudy.com>
> Sent: Wednesday, November 28, 2007 11:17:38 AM
> Subject: IP helper address - strange behavior
>
> Here is a quick diagram. Forgive my lack of ascii prowess. IP's changed
> to
> protect the innocent.
>
> DHCP server vlan 100 IP address 10.10.100.100
> 3750 switch A - VLAN 100 address 10.10.100.1 connected to DHCP server
> 3750 switch A- VLAN 101 address 10.10.101.1 connection to 7301 router
> 7301 router A - VLAN 101 address 10.10.101.100 connection to 3750 switch
> 7301 router A- Interface g0/1 ip address 10.10.50.1 / 24 ip helper
> address
> pointing to 10.10.100.100
> DHCP client (3750 switch B with ip address dhcp on g1/1) connected to 7301
> router
>
> Routing uses very basic EIGRP with network 10.0.0.0 everywhere
> With the setup above the dhcp server would see the address coming in as a
> different subnet then the expected 10.10.50.0 / 24 so the lease allocation
> would fail.
>
> When I inserted another router in between the 7301 and the 3750 B switch
> and
> moved the ip helper address command to that router everything worked fine.
> No other changes were made. The message from the DHCP server was unable
> to
> allocate address unknown error.
>
> Couldn't find any similar behavior on Cisco or google.
>
> Has anyone seen strangeness such as this before?
>
>
> Thanks,
>
>
> --
> Gregory Wendel
> Springfield VA, 22153
>
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-- Gregory Wendel Springfield VA, 22153
This archive was generated by hypermail 2.1.4 : Sat Dec 01 2007 - 06:37:31 ART