DHCP problem

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Mar 29th, 2009
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Hi all

I have DHCP server on the central site and branch office is connected via IPVPN link to central site over MPLS cloud of service provider.from the router and switch of the branch office i can ping the DHCP server.Configured one vlan on the switch and given dhcp server ip as the ip helper address.But not getting any IP from the DHCP server for the vlan users.Attached the log of "debug ip dhcp server events".Please give me a solution



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thotsaphon Sun, 03/29/2009 - 12:18
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anvar,

Assuming that you already correctly configured the DCHP pool of that network on the DHCP server.

Would you please post the configuration on the branch router? Excluding sensitive information.


Note: Do you have any firewall or security policies applied between both ends?.



Toshi

anva12345 Sun, 03/29/2009 - 12:28
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Hi Toshi

DHCP scope is configured on the server and i am getting IP when we connected at the central site.But over the IPVPN link its not getting IP.My doubt is should i give source IP for the DHCP scope as the IPVPN-WAN link IP at the branch office or Interface VLAN Ip for which we configured the scope.Now we have given the INterface VLAn IP as the source IP in the DHCP scope at the server side.

thotsaphon Sun, 03/29/2009 - 12:36
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anvar,

Well, Are you using site-to-site vpn? If yes, Have you allowed the ip address of the vlan interface in the interesting traffic on the ACL?

However If you can provide the configuration, it will be good for us.


Toshi

thotsaphon Sun, 03/29/2009 - 12:59
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anvar,

Your configuration is good to me.

Don't tell me you have a "no service dhcp " command on your switch. I thought you don't.

Well, Do you have any firewall or ACL applied somewhere on the both ends?


Toshi

anva12345 Sun, 03/29/2009 - 13:07
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Toshi

we dont have "no service dhcp "command on the switch and there is no firewall or ACL on the interfaces

thotsaphon Sun, 03/29/2009 - 13:22
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Huh?

Sorry I just carefully saw your configuration.

Well, I have to ask you a question. Do the users use the switch the be a gateway? If not,then who? the router? Okay Well, What about these commands?


ON ROUTER

!

interface GigabitEthernet0/0

ip address 10.4.5.1 255.255.255.0

ip helper-address 10.1.251.50

!


Please tell me what's going on


Toshi

anva12345 Sun, 03/29/2009 - 13:33
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Toshi

Ip helper address is configured on the interface vlan of the switch.which is 2960 L2 switch.gateway should be the Router

thotsaphon Sun, 03/29/2009 - 13:36
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anvar,

Okay , I got it now. C2960 is just a layer2 switch. You need to add a "ip helper" command on the router.

The ip address on the layer2 switch is to manage the switch. if you want to manage this switch from the HQ site. Please do the following steps.

!

interface vlan 1

no ip helper-address 10.1.251.50

!

ip default-gateway 10.4.5.1


Trust me once. (grin)


Thanks

Toshi

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