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WLC - External DHCP - Multiple Subnets - Clients not getting IPs

Scenario:

WLC Management IP: 10.1.0.100

DHCP Server: 10.1.2.5

Location 1:

Management: 10.1.0.0/23 - VLAN 100

Servers: 10.1.2.0/23 - VLAN 102

APs: 10.1.14.0/23 - VLAN 114

Faculty: 10.1.16.0/23 - VLAN 116

Students: 10.1.18.0/23 - VLAN 118

Guests: 10.1.20.0/23 - VLAN 120

Location 2:

APs: 10.2.14.0/23 - VLAN 214

Faculty: 10.2.16.0/23 - VLAN 216

Students: 10.2.18.0/23 - VLAN 218

Guests: 10.2.20.0/23 - VLAN 220

Location 3:

same concept as above

I have different interfaces configured on the WLC for each subnet (vlan) - APs, Faculty, Students, Guests

I also have three WLANs (Faculty, Students, Guests) with AP groups and three SSIDs - one per WLAN that are the same for every location.

The problem is this:

APs at every location are getting an IP from the DHCP server.

Clients on all three SSIDs at Location 1 are getting IPs from DHCP server

Clients at all other locations are NOT getting IPs (again, the APs do)

Let me know what other information you need from me to help me solve this please. I have been pulling my hair out over this.

8 REPLIES
Hall of Fame Super Silver

Re: WLC - External DHCP - Multiple Subnets - Clients not getting

Just to add... Only local subnets can be configured on the wlc unless each site is layer 2 connected.

Here is an h-reap guide that will help

http://www.cisco.com/en/US/products/ps10315/products_tech_note09186a0080736123.shtml

Sent from Cisco Technical Support iPhone App

-Scott
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Hall of Fame Super Silver

Re: WLC - External DHCP - Multiple Subnets - Clients not getting

For the remote sites, you should configure the AP's in H-REAP mode. This will allow you to define what SSID should be mapped to what local vlan. When an ap is in local mode, all traffic tunnels back to the wlc. In H-REAP mode, you can define what SSID you want to drop off locally and what SSIDs you want to tunnel back.

Thanks,

Scott Fella

Sent from my iPhone

-Scott
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New Member

Re: WLC - External DHCP - Multiple Subnets - Clients not getting

Thanks for the quick reply. Problem is we have only Aironet 1231G (about 25 or so total). I understand those are not supported for H-REAP.

What I tried as a workaround was to setup DHCP on the WLC. This works fine but I am concerned about performance - maybe I don't need to be. I have 5 remote locations, each would need three scopes. Should I proceed with DHCP on the WLC?

Hall of Fame Super Silver

Re: WLC - External DHCP - Multiple Subnets - Clients not getting

You can or else you can use your current dhcp. I don't like to use the wlc as a dhcp server. The interface that you create on the wlc needs to be local to the site the wlc is on. The issue you may have is that AP's in local mode might loose connectivity to the wlc an bounce which will cause issue with clients.

Thanks,

Scott Fella

Sent from my iPhone

-Scott
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WLC - External DHCP - Multiple Subnets - Clients not getting IPs

You have 2 location with the IP scheme 10.2.14.0/23. Wondering how the Router will differentiate between these 2 sites based on the IP address

Thanks

NikhiL

New Member

WLC - External DHCP - Multiple Subnets - Clients not getting IPs

Location three does not have the same scheme. I was saying concept as in it follows the same pattern as location one and two (10.3; 10.4, 10.5; etc)

Scott, thanks again for your input. What you are saying is I can use subnet 10.1.22.0/23 or whatever for location two which will allow me to use the external DHCP server, is that correct?

Hall of Fame Super Silver

Re: WLC - External DHCP - Multiple Subnets - Clients not getting

That is correct. If you are layer 3 to the other locations, then you need to only define your local subnets and users from the other location will be placed in location 1 subnet.

Thanks,

Scott Fella

Sent from my iPhone

-Scott
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Hall of Fame Super Silver

WLC - External DHCP - Multiple Subnets - Clients not getting IPs

Just to add.... since all traffic will be tunneled back down to the wlc, make sure those subnets are large enough for all the devices that may join.  Depending on your link between the sites, you may or may not have issues due to the fact the ap's have to run in local mode.

-Scott
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