Wireless Access

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kmd
Contributor I
Posts: 23
Registered: ‎04-09-2015

ip-helper

 

Hi.
We have 4 Corridors
Corridor 400 stands alone on one side of the building.
We have an S2500 in the 400 Corridor that acts as our Primary Router.
 
We also have 2- S1500 in the 400 Corridor used for the AP's connectivity. That switch's gateway is the 400 Corridor S2500.
 
On the other side of the building we have 3 floors.
 
We have an S1500 in the basement for our AP's, an S1500 on the 3rd floor for the AP's and an S1500 on the 2nd floor for the AP's.
 
On the 2nd floor we also have another S2500 which acts as a secondary router, since 3/4 of the traffic comes from that side.
 
My question is, do i need to put the ip-helper on all vlan interfaces of each switch, or just on the vlan interfaces of both S2500's?
 
Thank you.

 

Guru Elite
Posts: 21,269
Registered: ‎03-29-2007

Re: ip-helper

Question:  What do you want to do?

 



Colin Joseph
Aruba Customer Engineering

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

kmd
Contributor I
Posts: 23
Registered: ‎04-09-2015

Re: ip-helper

[ Edited ]

Hi
I need to know if I need to put the ip - helper on each vlan interface on
every switch. I currently have it on my primary router.

Thank you for your quick response.


Guru Elite
Posts: 21,269
Registered: ‎03-29-2007

Re: ip-helper

In general, you would only put a helper address on the layer3 interface of a vlan.


Colin Joseph
Aruba Customer Engineering

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

kmd
Contributor I
Posts: 23
Registered: ‎04-09-2015

Re: ip-helper

[ Edited ]

I see.
I did put it on every vlan interface on one switch, before I reached out
for guidance. Will that create a problem? Would you happen to know the
command to remove the dhcp relay setting?
Thank you very much for your help on this.


Aruba
Posts: 1,290
Registered: ‎08-29-2007

Re: ip-helper

You would generally just put it on the vlan interface for the core switch/router.  If you add to every switch you could end up with multiple addresses being assigned to the same device and then wasted dhcp addresses, cause only one will be taken by the device.


If my post is helpful please give kudos, or mark as solved if it answers your post.

ACCP, ACMP, ACMX #294
mclarke@arubanetworks.com
Guru Elite
Posts: 8,637
Registered: ‎09-08-2010

Re: ip-helper

Whichever VLAN interface is the client's default gateway.

Sent from Nine

Tim Cappalli | Aruba Security TME
@timcappalli | timcappalli.me | ACMX #367 / ACCX #480
kmd
Contributor I
Posts: 23
Registered: ‎04-09-2015

Re: ip-helper

Hi.

Thank you for yoru continued help with my problem.

I do have DHCP relay on the s2500 core router\switch.

Originally, someone setup our current HP switches, using the Aruba S2500 as the router. There is one s1500 that is directly connected to the S2500, via a port channel, and that works fine without the dhcp relay on it.

When I go to upgrade other HP switches to the s1500,  the s1500 doesn't work until I put dhcp relay on it. But dhcp relay shouldn't be configured on each switch?

 

MVP
Posts: 1,414
Registered: ‎11-30-2011

Re: ip-helper

it depends on if you use l3 interfaces on those switch or just extend the l2 network. if they have seperate l3 interfaces / networks you need dhcp relay, if you just extend the l2 network the dhcp request ends up at the l3 interface of the core switch.

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