When does the secondary DHCP server (relay) used under a interface on the WLC - 5008 work?

[mark.chennell]

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Hi all
We had an issue with our primary DHCP server yesterday and it appears the WLC did not forward any DHCP requests to the configured secondary DHCP server (under the controller>interfaces>created interface)

I was trying to find information online about how this works but no joy;
Is it an active/standby setup?
or active/active

But that being said we so no request coming into the secondary if when the primary is up (or down)

Regards
Mark

[Rasika Nayanajith]

Hi Mark,

Dynamic interface should send DHCP discovery messages to both DHCP servers configured.

HTH

Rasika

[mark.chennell]

without sounding to offish ....

Do you know if this is actually how they operate or maybe differs depending on code (as in ... the cisco way vs the out in the field)

thanks

[Rasika Nayanajith · Accepted solution]

That is how it should work, not sure about different behavior on recent codes. 

I had a packet capture from a WLC & I saw dynamic interface sending DHCP Discover messages to both primary & secondary DHCP server in it.

HTH

Rasika

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[Rich R]

Agree with Rasika it forwards to both servers, that's how it work for us, primary & secondary - live/live.

Not aware of any differences on different code versions.

So that suggests the problem was not your WLC but rather your DHCP server or routing/firewalls/ACLs between the WLC and your secondary DHCP server.

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