Connectivity loss when modifying DHCP Snooping Vlans?

[rmorenobb]

Hi, 

I currently have DHCP snooping enabled on a site switch stack, as follows: 

ip dhcp snooping vlan 20,90,100,200,400

no ip dhcp snooping information option

ip dhcp snooping

DHCP snooping is working fine, no issues, but I need to modify the vlans configured, I want to remove vlan 20. 

I found that the only way to do this is to do the following: 

conf t

no ip dhcp snooping vlan 20,90,100,200,400

ip dhcp snooping vlan 90,100,200,400

end

That works, but what it does is clear the ipdhcp snooping binding database, and it does rebuild, I don't know how to only remove 1 vlan??

I've only did the above after business hours for other sites, but curious if this can be done during production hours without any impact in connectivity for end points? 

[Georg Pauwen]

Hello,

the command:

clear ip dhcp snooping binding vlan vlan-id

lets you clear the bindings per Vlan. Is that what you are looking for ?

[rmorenobb]

Hi, no, I want to remove Vlan 20 from dhcp snooping all together, but I don't want to impact the other vlan bindings. 

Up to this point, I've been removing the entire statement no ip dhcp snooping vlan 1,2,3, etc.

and then putting it back without the vlan 20.

this is what ive been doing 

conf t
no ip dhcp snooping vlan 20,90,100,200,400
ip dhcp snooping vlan 90,100,200,400
!
end
wri mem
!

that works, but it obviously wipes out the entire dhcp snooping database, the database will rebuild but i prefer not to do this method. 

[rmorenobb]

Yesterday evening, around 5:30 p.m., which I felt was safe to try the command, worked, with no impact.  My concern was that by removing the ip dhcp snooping vlan x,x,x,x.. command, that it might cause connectivity issues, but it didn't. 

So I guess I answered my own question, well except I only know to fully remove the statement, and not just remove one vlan within the statement.