Problem DHCP on L3 Switch

Unanswered Question
May 5th, 2008

Dear Expert and All,

I would like to ask you some quetion on DHCP, i had switch 6509 and all the client provide DHCP

by this switch and never release . I currently 100 user. and i setp DHCP start from 10 to 250. Last time

all the client used from 10-100.So on client ip 20,21,22,23 is doesn't work (i mean now not use this

ip address but it remmaber on switch)so when i take the new computer to plug on the switch it start for 101.

My question: Which command that release ip 20,21,22,23 and the new client renew ip 20,21,22,23?( I mean don't

want the new client catch ip start from 101 because ip 20,21,22,23 is free)

Could you advice Please?

Best Regards,


I have this problem too.
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hadbou Fri, 05/09/2008 - 07:38

"set interface sc0 dhcp release" is the command used to release the ip address assigned by DHCP

"set interface sc0" is the command used to assign a new no dhcp ip address.

"set interface sc0 dhcp renew" is the command to renew the DHCP assigned ip address.

For more information on this command refer:

join_sn09 Fri, 05/09/2008 - 18:12

Dear Hadbou,

thanks you for your advice.

The command that you gave me for OS but my switch is IOS.

Could you give me some command for IOS?

and i would like to know which command that we can release one or two IP not all.:)

Best Regards,



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