WLC+LWAP

[Toss Leey]

Hi

Is it recommended to be AP in different subnet than WLC, if yes could you please clarify why?, bcz i heard it is recommended to be AP in different VLAN than WLC bcz broadcast?!!

Thank you

[Rasika Nayanajith]

If it is small network, then you can keep WLC & AP on the same network. In this way AP will find WLC using L3 broadcast & you do not want to configure any WLC discovery mechanisms like DHCP option 43, DNS, etc

If you have a large number of access points & you put them on the WLC subnet,then all AP broadcast reach WLC. Which is a burden to WLC. So in such network I would put AP on different vlan to the WLC management and allow only wireless user vlans + wlc mgmt across trunk link between WLC & connected switch.

HTH

Rasika

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[Toss Leey]

Hi

but why AP will send broadcast, it will send only one time to know ARP, right? so there is no burden to WLC

Thank you

[Sandeep Choudhary]

Hi Fawzi,

As per my understanding:

The LAP broadcasts a CAPWAP discovery message on the local IP subnet. Any WLC that is configured for Layer 3 CAPWAP mode and that is connected to the same local subnet receives the Layer 3 CAPWAP discovery message. Each of the WLCs that receives the CAPWAP discovery message replies with a unicast CAPWAP discovery response message to the LAP.

and these AP continuously send the discovery message to check if WLC is alive or not.If you have more then one WLC then AP maintains a list of backup controllers and periodically sends primary discovery requests to each entry on the list.

These periodic discovery request/Messages make burden on network(If you have many APs or large network).

Hope it helps.

Regards

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[Toss Leey]

Hi

Thank you for your clarify, but what if AP in different VLAN than WLC, will not send periodically discovery to WLC to check if alive

Thank you

[Toss Leey]

.

[Rasika Nayanajith]

Refer this link as it describe what happen when AP reset. It send a L3 broadcast for on the VLAN where AP management. So if it is different to WLC mgt, then AP broadcast will reach to the device you configured as gateway for AP mgt vlan. It does not forward further to any other vlans including WLC mgt.

http://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/Mobility/emob73dg/emob73/ch2_Arch.html#pgfId-1027490

Refer this 8.0 config guide section as well. It describe all the possible WLC discovery methods including IPv6 discovery introduced in that code onward

http://www.cisco.com/c/en/us/td/docs/wireless/controller/8-0/configuration-guide/b_cg80/b_cg80_chapter_01100101.html#ID302

HTH

Rasika

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[gohussai]

Well it depends on your deployment.

You will keep the VLAN/subnet of LAPs and WLC Management same specially if its L2 small network ,in this way LAP will easily discover the WLC and join.

But if its L3 Deployment and large LAPs on remote sites then we use Ap-Manager interface and use option 43 and DNS options to let the LAP find the controller easily.

NOTE: But if its Layer-2 and you have huge number of LAPs deployed then you can put LAPs on different VLANs or group LAPs to avoid broadcast on L2 and segregate LAN logically.

Hope this will be helpful ;)