External DHCP on WLC 5508 on both remote site (flexconnect) and local AP's

[khan300]

Dear Experts,

I will be  implementing the design as per the attached diagram. The two sites are around 500 meters apart and are connected through an access port ( not trunk). They cannot be put in trunk as the client will not allow us to.They are routed through EIGRP. Please refer to the diagram attached.

I thought of doing internal DHCP for both remote AP's (flexconnect) and local AP's but I read that internal DHCP servers are not supported when using HA AP SSO on the wlc 5508. Since I'll be using that, there is no point using internal DHCP's.

Now since I'm new to external DHCP connected to controllers, can you please advise me where and how to put the external dhcp's with their respective vlans for both flexconnect site(vlan 235) and local site (vlan203)? Please refer to the diagram to have a clear picture.

Also what configuration will I need to do on the WLC Controller GUI.

You help and assistance would be greatly appreciated.

Please do not hesitate to ask questions for clarification.

[khan300]

The remote sites should get the ip address from the dhcp pool vlan 235 defined on the core switch on the remote site, which will then communicate with the WLC ( which is in a different network connected accross an access port)

[Ali Aqrabawi]

yeah you are totaly right. 

[khan300]

so i define the WLAN interface in the WLC. give it a name, port number 1 ( which is the same as management port).

Vlan Identifier ( 203 for one wlan and 235 for the remote wlan).

Ip address of the Wlan and netmask.

Gateway ( this should be IP address of the specific managment SVI defined on the core right ?, Management vlan is vlan 200 and the WLC's are also in the 200 vlan )

Primary DHCP Server ( This should be the IP address of the vlan 203 or 235 depending which WLAN being used?)

Sorry for being a complete newbie :D

[Ali Aqrabawi]

you right,

the gateway ip address on the interface(of the remote site clients) should be the gateway ip of the clients in 235 .

[khan300]

Meaning I should define in WLAN the default gateway to be the Managament vlans IP address in Network B ?

[Ali Aqrabawi · Accepted solution]

basiclly on the WLC you will have an dedicated interface for network B , in this itnterface you should configured the gateway ip address for the network B.

i hope i understand you correctly.

[khan300]

Thanks will try all this on a few days on the site and will update :)

[khan300]

Hi there,

I tried to configure all this but i encountered a weird problem. When I setup the DHCP pool on the core switch, The AP is getting the IP addresses from the pool but after a minute or so it disconnects and renews its ip address with a different one. The AP keeps doing that. HOwerver i have noticed if i attach a laptop or any other device like a temperuture monitoring system device, it gets the DHCP address and DOESN'T drop it and renew it again. It stays stable.

What could be the problem? is it option 60 or 43 problem? i tried them both and they didnt work. When i log into the AP through the console port i get the following log error messages:

CAPWAP-3-DHCP_Renew: could not discover WLC using DHCP IP. Renewing DHCP IP

CAPWAP-3-ErrorLog: invalid event 38 & state 2 combination.

Let me attach the screen shot

[khan300]

BTW just for your info, the AP and the access switch are connected through an access port, the access switch and Core through a trunk port. The core switch and WLC also through a trunk port.

[Ali Aqrabawi]

When a FlexConnect access point enters into a standalone mode, the following occurs:

• The access point checks whether it is able to reach the default gateway via ARP. If so, it will continue to try and reach the controller.

If the access point fails to establish the ARP, the following occurs:

• The access point attempts to discover for five times and if it still cannot find the controller, it tries to renew the DHCP on the ethernet interface to get a new DHCP IP.
• The access point will retry for five times, and if that fails, the access point will renew the IP address of the interface again, this will happen for three attempts.
• If the three attempts fail, the access point will fall back to the static IP and will reboot (only if the access point is configured with a static IP).
• Reboot is done to remove the possibility of any unknown error the access point configuration.

Once the access point reestablishes a connection with the controller, it disassociates all clients, applies new configuration information from the controller, and allows client connectivity again.

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-3/configuration/guide/b_cg73/b_wlc-cg_chapter_01110.html

[khan300]

I'm talking about local AP's not flexconnect remote AP's. The management vlan (vlan 1) and the vlan for AP's(vlan203) are in different vlans though.

what could be the problem here? I suspecting option 43? what do you think?

[Ali Aqrabawi · Accepted solution]

first :the option 43 is only to let the AP to discover the WLC , if you configured the WLC ip manually on the AP or if the AP joined the WLC then no need for opetion 43.

second: if the AP is in local mode then how it goes to stand alon mode, this is only happen for flex APs, can you send #show ap config general Cisco_AP ?

having the AP and the WLC management interface in different subnets should not make any trouble , but you should have connectivity between them(AP and management interface).

can you check on the WLC msglog , if the AP is sending a discovery request to a non-mangement interface ? this could be happen if you isolate the WLC interfaces physicly (assiagn a dedicated interface for a dedicate port on the WLC)

[khan300]

first: how do i configure the the WLC ip manually on the AP, I'll try that as well instead of option 43.

Second: I can send you the config tomorrow, The WLC is connected to port 1 which is also the mangement interface.

Maybe the option 43 is not working since WLC 5508 also has a 5508 HA with it on which i still havent configured the redundancy port.

Ill try a bunch of things tomorrow and will let you know.

Thanks

[Ali Aqrabawi]

--use these commands on the AP:

 -debug capwap console cli

-conf t

config capwap ap controller ip address <controller ip address>

--ok i will check the config if i have time for that.

thank you