vlan dhcp ip helper-address problem with dhcp client

Unanswered Question
May 14th, 2009

Here is the 3560 conf file:

interface Vlan25

description Test

ip address

ip helper-address


no ip forward-protocol udp tftp

no ip forward-protocol udp tacacs

sw_core#sh ip interface vlan25


Vlan65 is up, line protocol is up

Internet address is

Broadcast address is

Address determined by non-volatile

MTU is 1500 bytes

Helper address is

Directed broadcast forwarding is disabled




I have dhcp server on Microsoft win server 2003(address It works fine for non vlan network. I have created vlan 25. My clients are XPs. Dynamics DHCP allocation works fine for laptops, but it does not work for some of my computers. I have tried everything to reset TCP/IP stack etc.... with no avail. Then I have tried to trace dcp server with ethreal:

When I type the command:

ipconfig /renew

I have on ethreal screen monitoring dhcp server:

1. DHCO discover

but when I use xp support command dhcplock and type d (for discover) I have : DHCP discover DHCP offer

So where is the problem? I do not have any idea what to do next! It is normaly no capable to locate dhcp server, but with dhcplock it can do.

I have this problem too.
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mahmoodmkl Thu, 05/14/2009 - 05:13


I dnot understand u r config u have the same ip configured on 2 switches or its the same switch..if its the same switch then u have defined the ip on vlan 25 and vlan65 its the same ip,can u please explain how is the connectivity of ur devices and the reason for assigning the same ip on different vlan interfaces.



hoffenheim Thu, 05/14/2009 - 21:44

It is all vlan 25. I did not update what I cut and paste. So vlan65 is vlan25.


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