IP assignment issue for 3750G

[peter.zhu]

We have situation that some users unable to get dynamic ip connected on 3750G, IOS is 15.0 SE9. The dhcp server is reachable and ip scope is not full on dhcp server. Just wonder if any bug on 3750 cause the ip assignment issue and how to fix it

[Daniele Giordano]

Hi, is the 3750 used as a switch only?
Is the client in the same vlan of dhcp server?
Or, are the server and the clients in different vlans? is the 3750 used as a router between vlan?
In this last case do you use "ip dhcp helper address" under interface vlan?

Dhcp requests are sent in broadcast. If you have vlans you need to use ip helped address.

Let us know your notes.

Regards.

[peter.zhu]

yes, this is Layer 2 swtich and we have seperate VLAN for dhcp server & client.

[Daniele Giordano]

Do you have 'ip helper address' configured on the interface used as a gateway for the clients?

Regards.

[peter.zhu]

Yes Daniel, we have ip helpder set under SVI interface. The setting is correct.

[brselzer]

Hello Peter,

If you do a ping to the sever and source it from the SVI ip, the server knows how to get back to that subnet?

ping [server ip] source vlan [user vlan]

Was this ever working or new deployment? If you do a wireshark capture on the client, do you see any response from the server?

Hope that helps!

[chrihussey]

Is "spanning-tree portfast" enabled on the ports?

[paul driver]

Hello

As you most of your clients are receiving dhcp allocation can you confirm that the dhcp scope is large enfogh to accommodate all your users?

Also are these failed users wired/wireless or both and is this failure occurring on either?