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New Member

Need help on Cisco6509 DHCP

Hello,

Our network is separated into several vlans by Cisco 6509. DHCP service is supported by one NT server in Vlan1. Now the client which connects to Vlan1 port can not get IP address after releasing IP using WINIPCFG, even rebooting. But when in windows98, use WINIPCFG to renew, the IP can be got.

For other clients which have not been connected to Vlans, they connect to the normal HUB which shared with the DHCP NT server. After releasing IP, they can get IP using rebooting.

Re: for other vlans which are different from Vlan1, the clients can not get IP after rebooting. But they can get IP through winipcfg renewing. (the other vlans have been configured to use DHCP IP POOL which is the function of cisco6509)

We are confused on it and the users will be impacted if put them to Vlans as they would be frustrated to use WINIPCFG during boot up of the system.

Thanks,

Morris

4 REPLIES
Cisco Employee

Re: Need help on Cisco6509 DHCP

Morris,

it sounds like perhaps the DHCP requests timeout before the switch port is in an STP forwarding state.

Have you configured 'portfast' on user ports to speed-up STP process ?

Another option (depending on you sw version) is to configure 'set port host' which is a macro-command disabling certain parameters such as trunking/channelling and enabling portfast in effort to get a user port up and forwarding asap.

Important to note is that these commands must -only- be used on single *user* ports please see the following URL for more info:

http://www.cisco.com/warp/public/473/12.html#startup5k

Hope it helps

steve

New Member

Re: Need help on Cisco6509 DHCP

Hello, Steve

The problem was solved after setting spantree portfast to the user ports. very appreciate for your kind help!

Hi MickPhelps,

Only one vlan uses NT DHCP, others are using DHCP server on Cisco6509.

Thanks,

Morris

New Member

Re: Need help on Cisco6509 DHCP

Another note on your implementation.

You say that DHCP is running on one NT server, yet you use a DHCP pool on the 6509.

Add IP HELPERs to your VLAN interfaces on the MSM/MSFC that point to the NT server. You may be having an issue with DHCP assiging duplicate IP addresses if your scope on the 6509 overlap your scope on the NT server.

Mick.

New Member

Re: Need help on Cisco6509 DHCP

No overlap, separate Vlan - but now I face another issue, when one PC connected to one Vlan, get one IP through DHCP, but when it changes to another vlan, the IP can not be auto-renewed even after rebooting. I need to use WINIPCFG to release IP first then renew manually.

Do you know what's the root cause?

Thanks,

Morris

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