Wireless Client not able to get ip address from internal DHCP server (h-reap)

[csco11180321]

Hi,

I am having AIR-WLC4402-50-K9 in which i have connected some access points in H-Reap Mode.I am running 7.0.98.218 code on this WLC. I have DHCP server configured on WLC. unfortunately client are not able to get dhcp ip address from dhcp server. I had configured ip-helper address <dhcp server ip> on user vlan.

Upon debug of client & dhcp messages on Controller i am getting below.

debug client:

*apfMsConnTask_0: Dec 22 15:41:36.515: 20:7c:8f:1d:ea:14 0.0.0.0 DHCP_REQD (7) Change state to START (0) last state DHCP_REQD (7)

*apfMsConnTask_0: Dec 22 15:41:36.515: 20:7c:8f:1d:ea:14 0.0.0.0 START (0) Initializing policy

*apfMsConnTask_0: Dec 22 15:41:36.515: 20:7c:8f:1d:ea:14 0.0.0.0 START (0) Change state to AUTHCHECK (2) last state DHCP_REQD (7)

*apfMsConnTask_0: Dec 22 15:41:36.515: 20:7c:8f:1d:ea:14 0.0.0.0 AUTHCHECK (2) Change state to L2AUTHCOMPLETE (4) last state DHCP_REQD (7)

*apfMsConnTask_0: Dec 22 15:41:36.516: 20:7c:8f:1d:ea:14 0.0.0.0 L2AUTHCOMPLETE (4) Plumbed mobile LWAPP rule on AP 2c:3f:38:31:17:90 vapId 5 apVapId 5

*apfMsConnTask_0: Dec 22 15:41:36.516: 20:7c:8f:1d:ea:14 0.0.0.0 L2AUTHCOMPLETE (4) Change state to DHCP_REQD (7) last state DHCP_REQD (7)

*apfMsConnTask_0: Dec 22 15:41:36.516: 20:7c:8f:1d:ea:14 0.0.0.0 DHCP_REQD (7) pemApfAddMobileStation2 2518, Adding TMP rule

*apfMsConnTask_0: Jun 21 08:00:48.516: 20:7c:8f:1d:ea:14 0.0.0.0 DHCP_REQD (7) Adding Fast Path rule

  type = Airespace AP - Learn IP address

  on AP 2c:3f:38:31:17:90, slot 0, interface = 1, QOS = 0

  ACL Id = 255, Jumbo Fr

after fast path rule it starts from change state to start(0)..

On controller i am getting below message when debug dhcp message enable..

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.042: 20:7c:8f:31:54:1d DHCP option: message type = DHCP DISCOVER

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option: 116 (len 1) - skipping

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option: 61 (len 7) - skipping

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option: 12 (len 14) - skipping

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option: vendor class id = MSFT 5.0 (len

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option: 55 (len 11) - skipping

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option: 43 (len 2) - skipping

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP options end, len 72, actual 64

*DHCP Proxy DTL Recv Task: Dec 23 11:25:37.043: 20:7c:8f:31:54:1d DHCP option len (including the magic cookie) 72

then again message type = DHCP Discover.

Can any one tell me, can i configure internal dhcp server on WLC when H-reap mode enabled for LAP having local switching is enabled.. if yes then any config mistake i am doing above.

[csco11180321]

I have also observed then h-reap mode is disabled the wireless clients are getting ip address from internal dhcp server configured on controller properly.

[nikhilcherian]

With HREAP local switching enabled, client will try to get the IP address from the local DHCP pool only . The AP will not send the request to the WLC and hence your clients will not get Ip address from the internal DHCP pool

IDHCP pool is not recommended with HREAP local switching

Thanks

NikhiL

[csco11180321]

Thanks a tonne..

Is there any OEM document do you have relating to this limitation.

[nikhilcherian]

The documents mentions the DHCP server should be locally available and reachable locally to the AP

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

search : Clients Cannot Connect to the H-REAP

or https://learningnetwork.cisco.com/servlet/JiveServlet/previewBody/5545-102-1-17739/h-reap-design-deploy.pdf
search :

H−REAP WAN Considerations

Thanks

NikhiL

[csco11180321]

Thanks for the link.. In link....

H-Reap design & Functional Limitation.. it is given (An H REAP access point can be deployed with either a static IP address or a DHCP address. In the case of DHCP, a DHCP server must be available locally and must be able to provide the IP address for the access point at bootup) This is only for LAP. In my case Access Point is already registered with WLC with Static IP.

On Clients cannot connect to H-Reap section...(Ensure clients on locally switched WLANs are  properly IP addressed. If DHCP is used, make sure an upstream DHCP  server is properly configured and providing addresses to the clients. If  static addressing is used, ensure the clients are properly configured  for the correct subnet.)

I am confused about upstream DHCP server.. is it locally configured DHCP server or DHCP server configured on WLC or DHCP server configured on Remote location.

In our scenario wireless client which is confgured on H-Reap should get IP address from WLC DHCP server.

Regards..Pramod.

[nikhilcherian]

In HREAP local switching, when the client sends the DHCP request, AP will forward the request to the infrastructure switch rather than forwarding to the WLC. The infrastructre switch will take this request, and see the ip helper address configured for the specific vlan and forward the request to this helper-address. In case your DHCP server is the WLC, when the WAN link to the remote location goes down, AP and infra switch in the remote location will be isolated from your WLC in the central location. This means there will be no reachability to the DHCP server from your HREAP AP, which will prevent the clients from gettin IP address

Thanks

NikhiL

[csco11180321]

Hi Nikhil,

So as per your previous thread the client which are connected to H-Reap access point should get ip address from the WLC DHCP. In case WLAN link goes down, new ip won't be assined any new client.

But,

In our scenario the client which are connected to H-Reap access Point are not getting ip address from WLC DHCP, the wan link is proper. We also configured IP helper address as Controller's ip address on local switch, still facing issue.

Regards..Pramod.

[csco11180321]

Where should be the DHCP server placed in our scenario, whether on WLC or External DHCP server at each remote location.

[nikhilcherian]

An external DHCP server should be placed in the remote location, may be you can use your infra switch for this

Thanks
NikhiL

[csco11180321]

Thanks Nikhil,

Means we cannot use WLC as dhcp server when ever H-Reap(local switching) mode is enabled & we need to place DHCP server locally(either in infra switch or external dhcp server in same vlan).

[nikhilcherian]

Yes, that is correct.