SG300 Multiple DHCP forwarders for VLANs

[Bjorn Dirchsen]

Hi Guys,

I'm setting up a network where I have 2 VLANS (VLAN20 and VLAN30) from a main Cisco switch, trunk'ed to an SG300-10PP switch (in L3 mode).

I have managed to configure a DHCP relay for VLAN30 using DHCP server 10.10.0.1. But I need to configure another DHCP server for a different VLAN - VLAN20 - using DHCP server 192.168.1.1.

Ports 1-4 should be assigned to VLAN20 and port 5-8 to VLAN30. The assignment (or join) is not the problem, but I cannot see how i can "link" a DHCP server to each VLAN.

I can add a number of DHCP servers in the settings, but how does the swich know which DHCP server to choose?

DHCP Relay Server TableDHCP Server IP Address

10.10.0.1

192.168.1.1

Am I missing something? (very likely ;))

Best regards,

Bjorn Dirchsen

[pieterh · Accepted solution]

you cannot link a dhcp server to a vlan! (dhcp=layer-3, vlan=layer-2)

you can assign an SVI/VIP (virtual interface IP address) to a vlan and assign a DHCP relay for this interface
if the DCHP server is the SG300 itself, then you do not need a DHCP relay,
just configure a SVI/VIP and the DHCP scope of course, the SVI/VIP and scope are matched by the subnet used
so you need to a configure an IP-address for each vlan where you need DHCP or DHCP-relay

[Bjorn Dirchsen]

Thanks a lot @pieterh. I followed your suggestion and now I have two nice VLANs on completely different subnets with IP addresses being served from the firewall.

Best regards,

Bjorn Dirchsen

[pieterh]

good to hear you made it work
and thank you for marking my answer as solution
Best Regards,

Pieter