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New Member

SG300 - DHCP implementation

Hello and thanks in advance for your help.

I set an SG300 switche in layer 3 mode with 3 vlans.

I need to give IPs to a whole vlan machines. Do the switch have a DHCP server per vlan? Can someine help me to configure this?



Re: SG300 - DHCP implementation

Hi Angel,

As the datasheet says;

Dynamic Host Configuration Protocol (DHCP) Relay at Layer 2

Relay of DHCP traffic to DHCP server in different VLAN. Works with DHCP Option 82

The DHCP Address Allocation Using Option 82 feature provides the  Dynamic Host Configuration Protocol (DHCP) server the ability to allocate dynamic IP addresses based on the relay information option (option 82) information sent by the relay agent.

Automatic DHCP address allocation is typically based on an IP address, whether it be the gateway address (giaddr field of the DHCP packet) or the incoming interface IP address. In some networks, it is necessary to use additional information to further determine which IP addresses to allocate. By using option 82, the  relay agent has long been able to include additional information about itself when forwarding client-originated DHCP packets to a DHCP server. The DHCP Address Allocation Using Option 82 feature now allows the DHCP server to also use option 82 as a means to provide additional information to properly allocate IP addresses to DHCP clients.

In our case option 82 information includes which VLAN the DHCP request came from.

regards Dave

New Member

SG300 - DHCP implementation

David, If not annoying, can you give me an example of configuration?

I have vlan 10 and want to use a dhcp server on vlan 20. How should I configure that?


New Member

SG300 - DHCP implementation


If I have my core switch in layer 3 mode and several others  switches but in layer 2 mode. Where should i configure dhcp relay? All  switches or only in layer 3 switch?

I have 3 vlans and the dhcp server in other vlan. This dhcp server should give ip configuration to all vlans.

Thanks a lot in advance.

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