MULTIPLE DHCP SERVERS, VLANS

[kurtsalvador1]

MODEL : SG 500 - 28p

I have setup the following VLANS
 

900 -> Management
200 -> DHCP Server configured on the switch ;
180 -> External DHCP​ <- not working

I've got a multi-scope DHCP server running on VLAN 900 (ip address 172.16.17.2 ) and I want to serve the following pools to their respective VLANS (to remove the DHCP server burden from the switch) : 172.16.20.0/24 to VLAN 200, and 172.16.18.0/24 to VLAN 180. Is this possible ?

VLAN 200 is 172.16.20.1 /24
VLAN 180 is 172.16.18.1 /24
VLAN 900 is 172.16.17.1 /27

I setup port 13 to access VLAN 180 and issued the following command ip-helper address 172.16.17.2 under interface VLAN 180 and it says missing mandatory parameter.

So it seems that the correct parameter for the SG 500 is : ip helper-address {ip-interface | all} address [udp-port-list]

Question: what should be the {ip-interface} value and the address value?

I tried ip helper-address 172.16.17.2 172.16.18.1 and it didn't work. I also tired reversing it, still no go.

So the other question is should the external DHCP server reside on the same VLAN ?

[Mark Malone]

Try enabling dhcp relay with ip helper under the vlan interfaces have a look at the doc below  , i think your switch needs to be set to l3 as well

https://www.cisco.com/c/dam/en/us/td/docs/switches/lan/csbms/Sx500/administration_guide/500_Series_Admin_Guide.pdf

[kurtsalvador1]

Hi Mark,

Thanks for responding.  Yes, the switch is in L3 mode, inter-VLAN routing is working and all clients can access the Internet.  Would like to unburden the switch from doing DHCP tasks.

Will check out the doc and get back to you later.