S4 DHCP Bindings

[Philipp_Tittman]

Hi Guys,

on a S4 Switch i have a dhcp pool enabled on a vlan. when i do "show ip dhcp binding" there are a lot of addresses with status "blocked" without any MACs associated. Does anybody know what that exactly means or when did this status appears?

Thanks in advance
Phil

[Careno__Ryan]

GTAC Knowledge:
https://gtacknowledge.extremenetworks.com/articles/Q_A/Why-does-S-N-K-Series-show-DHCP-Binding-state...

[Philipp_Tittman]

Hi Ryan,

great! Thank you very much

Regards,
Philipp

[Careno__Ryan]

Hello Phil,

Please see the following GTAC Knowledge article I just published:

https://gtacknowledge.extremenetworks.com/articles/Q_A/Why-does-S-N-K-Series-show-DHCP-Binding-state...

The router sends a ping to an IP address before offering an IP address to a client. If the IP address gets an ICMP response, we see there's someone already on the network with that IP address and mark it as "blocked" so we do not hand out duplicate addresses.

Once you find the client that already has the IP address in the DHCP scope (possibly set statically), you should be able to clear up the blocked binding with command "clear ip dhcp binding "

Regards,
Ryan Careno