From: v.shekhar@yahoo.com
Date: Wed Nov 28 2007 - 03:14:35 ART
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
This archive was generated by hypermail 2.1.4 : Sat Dec 01 2007 - 06:37:31 ART