DHCP Snooping- PCs are not taking IP address after enabling DHCP snooping

[Ramz PV]

Hi,

    I have enabled DHCP snooping in our network. but after enabling the same, User machines are not getting IP address from DHCP server. I have attached the network diagram with all details. kindly assist me to sort out this issue.

[paul driver]

Hello

Are you trusting also the interfaces towards your dhcp server?
Is DHCP option 82 enabled?

check by:
sh ip dhcp snooping

If this is enabled then try trusting dhcp relay on those interfaces

int x/x
ip dhcp relay information trusted

 

res

Paul

[Ramz PV]

Hi Paul,

       Option 82 is enabled. I have configured "ip dhcp snooping trust" on all the trunk interfaces. please note that dhcp snooping is not enabled in the server farm switches where DHCP server is connected.

Regards,

Ramith

[johnd2310]

Hi,

What IOS version is running on the access switch? Some version of 15.0  have broken dhcp snooping.

Thanks

John

[Ramz PV]

Hi John,

    IOS Version 12.2(55)SE8 is running in my 3560 access switches.

Regards,

Ramith

[Ramz PV]

Hi all,

    I have tried "ip dhcp relay information trusted" and "no ip dhcp snooping information option" and still the PCs are not getting IP address from DHCP server. but as soon as I remove dhcp snooping command from the switch, it started working. please help.

FYI : All the PCs are connected through AVAYA phones and the access interfaces are configured with Access vlan and Voice vlan.

[Harrie Hendriks]

We have a Microsoft DHCP server and we are not using option 82.

no ip dhcp snooping information option

Regards Harrie