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MVP
Posts: 1,405
Registered: ‎05-28-2008

DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

[ Edited ]

Hi Guys,

09-02-2014 13-39-42.jpg

 

I have a short question regarding the configuration of DHCP helper when using trunk port to the external dhcp server.

 

Do i need to configure in each VLAN the dhcp helper VLAN1 ip address or the ip address of the DHCP helper  in the specific VLAN?

 

Please advise.

 

Thanks.

 

Me

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Guru Elite
Posts: 20,819
Registered: ‎03-29-2007

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

In Each VLAN that you want to provide DHCP, you need to configure a helper address pointing to an external DHCP server.



Colin Joseph
Aruba Customer Engineering

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MVP
Posts: 1,405
Registered: ‎05-28-2008

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

The IP of the extranl server on vlan1 or the IP of the extranl dhcp server on that same vlan ?
Its two different IP'S
*****************2Plus Wireless Solutions****************************
Aruba Airheads - Powered By community for empower the community
************ Don't Forget to Kudos + me,If i helped you******************
Guru Elite
Posts: 20,819
Registered: ‎03-29-2007

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

You only have one DHCP server, ip address 1.1.1.1.  On each VLAN that you want that server to work on, you need to configure:

 

config t

interface vlan x

ip helper-address 1.1.1.1

interface vlan y

ip helper-address 1.1.1.1

interface vlan z

ip helper-address 1.1.1.1

 

You can either do that on the controller, OR on the device that is the router for VLAN x, y or z.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

MVP
Posts: 1,405
Registered: ‎05-28-2008

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

Thanks

For that  i aware....

 

But the DHCP SERVER got an IP on each VLAN,not only in VLAN 1....

For example:

 

Capture.PNG

 

DHCP SERVER ADDRESS ON VLAN 95 is 10.97.0.2 | and on VLAN 100 it's 10.20.0.2...

do u understand my question?

 

*****************2Plus Wireless Solutions****************************
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************ Don't Forget to Kudos + me,If i helped you******************
Guru Elite
Posts: 20,819
Registered: ‎03-29-2007

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

If the DHCP server has an ip address on each VLAN, then you DONT need a helper address statement in those VLANs.  It should not be done like that, however.....



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

MVP
Posts: 1,405
Registered: ‎05-28-2008

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

Thanks (Love u'r fast answers )
*****************2Plus Wireless Solutions****************************
Aruba Airheads - Powered By community for empower the community
************ Don't Forget to Kudos + me,If i helped you******************
Guru Elite
Posts: 20,819
Registered: ‎03-29-2007

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

You are welcome.

 

You should not need an ip address, because the DHCP server should be able to see the DHCP broadcast in those subnets and respond to them.  You only need a helper address if the ip address of the DHCP server is not in the same vlan and it needs to be "helped" to see DHCP broadcasts.



Colin Joseph
Aruba Customer Engineering

Looking for an Answer? Search the Community Knowledge Base Here: Community Knowledge Base

MVP
Posts: 1,405
Registered: ‎05-28-2008

Re: DHCP Helper question | Trunk port to the external DHCP SERVER | Multiple Vlans

GOOD INFO | GOOD TIP
*****************2Plus Wireless Solutions****************************
Aruba Airheads - Powered By community for empower the community
************ Don't Forget to Kudos + me,If i helped you******************
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