Introduction
central dhcp Processing - Locally switched remote wireless client getting ip from WLC or via WLC.
When using Flexconnect local switching, Dhcp request is sent/bridged to the flexconnect AP connected local switch. On Enabling central dhcp option from flexconnect group, dhcp request can be forwarded to WLC for DHCP ip assignment to the locally switched wlan.
How to Configure
Create Flexconnect group.
On central dhcp tab, configure the wlan id and check central dhcp and click add. Repeat the step if multiple WLANs are used.
Add intended APs to that group.
How it works
Using the flexconnect group feature -> 'central dhcp' the remote wireless client that is locally switched will get an ip from WLC's interface that is mapped to that locally switched wlan. Can use WLC's internal or external dhcp server.
WLAN - Locally switched
From WLAN tab -> Interface mapping for wlan id 5 is vlan120 = 120
From AP's Flexconnect tab -> AP's WLAN to vlan mapping -> wlan id 5, vlan id - 120. Without AP group configured, still client will get an ip from vlan 120.
Scalability is achieved using AP group
Use AP Group to override vlan for specific wlan and add the flexconnect ap to that AP group.
WLAN - Locally switched
From WLC's interface tab - Create vlan2000 interface with interface ip, gateway, mask and dhcp server(internal/external). vlan id 2000 is similar local vlan at the site.
From WLAN tab -> Interface mapping for wlan id 5 is vlan120 = 120. It doesn't matter what is configured here, ap group will override the vlan interface.
From AP group map the ssid with interface vlan 2000.
From AP's Flexconnect tab -> AP's WLAN to vlan mapping -> wlan id 5 to vlan id - 2000.
Troubleshooting
'Client debug' on WLC will show the debug transaction until 'RUN' state for central dhcp feature.
Example
Let say there are 3 sites, each using different vlan ie., 100, 200, 300 and using same ssid ie., ssid-remote.
1. create three different interface on WLC i.e, vlan - 100, 200, 300 based on the remote location.
2. configure internal/external dhcp scope for these vlan - 100, 200 & 300.
3. On WLC it doesn't matter what interface configured for ssid-remote ie., management.
4. configure 3 AP groups. AP group 1 with ssid-remote mapped to 100, AP group 2 with 200 and 3 with 300 for same ssid.
5. Add the respective APs to those AP group
6. On individual AP map the ssid-remote with respective vlan ie., ssid-remote with 100,...
