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WLC DHCP proxy issue

Rafael Jimenez
Level 4
Level 4

Hello experts,

 

I started an implementation of a CT-5520 few days ago.

I started deploying some 3802 AP per day. I affronted several problems in the way.

The first problem was with dhcp server. A quasi hidden no service dhcp command in the L3 Cat Switch. This command blocks the 37, 49, 53, 67, 68, 69, 116, 137 and 138 udp ports.

Well the end customer decided leave the command. I had move the dhcp server, APs and WLC to the same VLAN. For the wireless clients, dhcp proxy was the solution.

In some point I reached the 68 APs installed, an average of 500 wireless clients.

I'm not sure what happened in the lan infrastructure, the end customer says "nothing has changed", but suddenly looks like the dhcp proxy don’t work anymore. The wireless clients were unable to get an ip address. After a couple of days with this issue without a permanent solution. I told the customer several options:

- add two more vmnics to the dhcp server, one in the first wlan interface vlan and the last in the other       wlan interface vlan.

or

- move the wlc ports, aps to the same physical swith where the dhcp server VM has the uplinks and         move the interface vlan with ip helper commands to this switch.

or

- put the default service dhcp command in the L3 switch.

 

The end customer decided put back the service dhcp command.

 

My question is, why dhcp proxy functionality just do not work anymore?

 

The TAC checked the wlc config, confirm that the config was ok, with the conclusion that may be an issue in the lan infrastructure.

 

I think the same, but sometimes come to my mind that may be a bug. I see many bugs related with the wlc code with 3800 aps.

 

I would like hear your comments.

Thanks.

1 Reply 1

Rafael Jimenez
Level 4
Level 4

Looks like is a long history....

Well sumarizing the problem, 
can 68 APs with about 500 clients affect the performance of the wlc due to proxy dhcp unicasts to the external dhcp server?

 

why dhcp proxy functionality just do not work anymore?

 

 

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