IP DHCP Snooping Binding Empty

[mohammedsalih]

hi every one,

i have more than 25 Switch 3750,3560,2960 connected together ,

in the main Sw is 3560 L3 (the top of them) i have three vlans 10,20,30 and enable DHCP Server for each vlan,

i also enabled DHCP Snooping in all switches and DAI ,

the configuration of DHCP Snooping and DAI :

B1-SW-P1(config)#ip dhcp snooping

B1-SW-P1(config)#ip dhcp snooping vlan 10,20,30

B1-SW-P1(config)#no ip dhcp snooping information option

B1-SW-P1(config)#ip arp inspection vlan 10,20,30

B1-SW-P1(config)#ip arp inspection validate src-mac

all uplink to the main SW configured as Trust DHCP Snooping

B1-SW-P1(config-if)#ip dhcp snooping trust

all trunk ports configured as Trust DAI

B1-SW-P1(config-if)#ip arp inspection trust

the problem is some Switches work fine and some of them not work

when i check the snooping binding table it is empty and the devices attached to the SW not assigned ip address

and if i remove dhcp snooping the devices get ip's ,

i tried alot and i didn't figured what is the problem

[Flavio Miranda]

Hi

  What I´d suggest first is to check for pattern like switch model and IOS version. This can easily be a bug.

 Other then that, try to look the logs for those not working switches.

[mohammedsalih]

i think about IOS Version too,

but i didn't check, i will try different IOS and tell you the result.

thanks for replying.

[MHM Cisco World]

These non work SW connect to trunk to core SW, this trunk allow other vlan (vlan that not config with snooping)? 

[mohammedsalih]

Hi,

yes, there are  other vlans that i didn't enable dhcp snooping config , because i don't need Snooping fot it

[MHM Cisco World]

""all uplink to the main SW configured as Trust DHCP Snooping""

The uplink config with dhcp snooping but not config with arp inspection trust' why ?

[M02@rt37]

@mohammedsalih 

@MHM Cisco Worldis right:

By configuring both DHCP snooping trust and ARP inspection trust on the uplink interfaces, you allow DHCP traffic and ARP packets to traverse those ports without interference. This ensures that DHCP requests can reach the DHCP server and that ARP packets can be properly inspected and validated.

[mohammedsalih]

"" all trunk ports configured as Trust DAI

B1-SW-P1(config-if)#ip arp inspection trust ""

i already configure it

[mohammedsalih]

yes

[M02@rt37]

Hello @mohammedsalih,

Ensure that there are no connectivity or spanning-tree issues on the switches that are not working. Verify that the spanning-tree topology is correct and there are no blocking or forwarding issues.

[mohammedsalih]

the spanning-tree is work fine, i have no problem with it .

[MHM Cisco World]

Few Q please can you answer it

1- SW platform and IOS ver.

2-are you config up link with port channel

3-are you config device tracking

4-are you config dhcp relay

[AlwaysBeginner]

Try to add the command "no ip dhcp snooping information option"