dhcp renew lease

[malshara]

Dear All ,

I have an issue when a client move from one AP to another ,it asked to renew its IP address now I checked the DHCP packet on the core switch I found that the source mac address for the end client and the destination MAC as a broadcast ,and regarding the source ip address for the end client and the destination for the DHCP server .

after 2 tries REQUESTs to renew the ip address the operation failed and the client send a broadcast DISCOVER again and the client get the same IP address again.

is it expected to see the destination MAC address as a broadcast ? and why the switch drop the REQUESTs ?

I attached a screenshot a sniffer capture .

Thanks in advance

[johnd2310]

Hi,

Is this a controller based wireless  network? If this is a controller based wireless network, have you defined ip helper on the core switch or on the controller? Is the client doing a L2-Roam or a L3-Roam. Are the controller configured the same? e.g mobility

Thanks

John

[malshara]

hi John ,

yes this a controller based wireless network ,the ip helper defined in the core switch ,the controllers confiured the same ,and the client did a L2 roaming.

attached a simple topology

Thanks for assistance

[Masoud Pourshabanian]

Hi,

Is any security feature set on the switch? All DHCP messages come to one port of switch or different ports?  I mean each AP is connected to a separate port of switch or all of them terminate to one port?

[malshara]

hi masoud,

yes there is a dot1x configured and the client did a full authorization ,the AP connected to a different WLC  ,all the both WLCs terminated to a one port on the core switch "6K"