DHCP-Snooping

[saeedek]

i have access switches cat 9300 connected to core cat 9500.Core has GW for all vlans.

then cat 9500 connected to DC through cat 6800.in DC there is DHCP server how i can apply dhcp snooping on cat 9300 and cat 9500 ?

i enabled dhcp snooping @ cat 9300 and 9500. from access i make trust port to up links.and from core side i use helper address and use globally no ip dhcp information option,ip dhcp snooping information option allow-untrust.

is this enough ?

[Georg Pauwen]

Hello,

what you configured sounds about right. What are you running into, is your setup not working ?

[balaji.bandi]

as Long as the DHCP server reachable to ACCESS Switch and CORE Switch towards DC where DHCP running, below config works high level.

ip name-server y.y.y.y
ip domain list domain.com
!
ip dhcp snooping vlan XXX,YYY
no ip dhcp snooping information option
ip dhcp snooping

!

interface VlanXXX
ip helper-address DHCP1IP
ip helper-address DHCP2IP

[saeedek · Accepted solution]

it's working fine
these are configuration

Access SW

=========

ip dhcp snooping vl x,y,z

ip dhcp snooping

no ip dhcp snooping information option

int po x

ip dhcp snooping trust

Core SW

=======

ip dhcp snooping vl x,y,z

ip dhcp snooping

no ip dhcp snooping information option

int vl x

ip add z.z.z.z

ip helper-add c.c.c.c

now all users are able to get ip add from DHCP server

thanks all for support

[Giuseppe Larosa]

Hello @saeedek ,

enabling DHCP snooping on the core switch may be avoided if no end user devices are connected directly to it,  configuring it at access layer is enough.

In the past I have had issues with DHCP snooping enabled on core switch on WLC connecting port channel we had to put it in dhcp snooping trust mode otherwise wireless users could not get an IP address.

Hope to help

Giuseppe

[balaji.bandi]

Glad to know all working as expected, we mark as solution, so it will be usefull for other community members can use.