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Creating new VLAN on SG300

Hello folks.

I'm working for an organization that has multiple SG300 switches and 4 VLANs (VLAN10, 20, 30, and 40).

I'm at a point where I need to add a new VLAN to the existing network but I've never done it before.

I've been able to create a new DHCP pool and sub interface on the router and I've learned how to create a VLAN on the SG300 and assign a port to it. 


The problem I'm having is that I can't figure out how to configure the switch to get ip addresses from the new VLAN on the router.


I appreciate any help you can offer.  Thanks

Cisco Employee

Re: Creating new VLAN on SG300


Please allow the mentioned VLANs on the Trunk link (Switch port which is connected to the Router).

What is the Router model you are using? You have not provided the IP address details of the DHCP server and VLAN interfaces, in case hosts and remote DHCP server are not on the same network then you may use the ‘DHCP Relay’ option. Please refer the below mentioned link regarding DHCP relay configuration…


It will be good to have a Network topology along with the IP address details to understand your scenario better, if possible, please add the same.


Re: Creating new VLAN on SG300

Thank you for your response.

The router being used is an Adtran Netvanta 4430.  It currently has 4 sub interfaces setup for the different VLANs.  The IP addresses are:


I've created a 5th VLAN on the 4430 and would like to configure the Cisco switches to pull DHCP from that.

I was able to create a VLAN on the switch I'm connected to in my office and am trying to configure an unused port for testing.

I did configure the trunk port with the new VLAN.

When Log into the switch, DHCP relay does not appear to be enabled.


Thank you.


Re: Creating new VLAN on SG300

From CLI enter commands:

#conf t
#vlan database
#vlan 10
#vlan 20
#vlan 30
#vlan 40
#gvrp enable

then edit interface from SG300 to Adtran. GE1 in example:

#interface GE1
#switchport mode trunk
#spanning-tree portfast
#gvrp enable
#description TO_ADTRAN_4430
#do write



Re: Creating new VLAN on SG300

So looking at my previous posts, I forgot to mention that I'm new to VLANs and switches. So far I've only worked on small office networks.


So problem number 1 that I'm noticing is that when I telnet into the SG300, I get a DOS type menu (sorry, I don't know the correct terminology yet) and I don't see an option to go into CLI.


The version I see is for this unit.

Somehow, the switches have been setup using either the GUI or this black screen text menu.


Problem number 2 is a concept problem that I haven't been able to find an answer for yet.

Once you've setup the VLAN on both the switch and router, and you have multiple VLANs, how does the switch know which DHCP pool to pick from? I can't find a setting anywhere on the switch that in effect says "Port 5 which is assigned to VLAN 50 should get an address from the" on the router as opposed to any of the other DHCP pools there.


I hope I'm making sense and not confusing the issue for anyone else.  Thanks again to everyone helping me out.


Re: Creating new VLAN on SG300

1. CLI - Command Line Interface. This is DOS type menu when connect via ssh/telnet:) 

2. DHCP use multicast packets in  protocol. PC send request DHCPDISCOVER to and wait response from server. In your case DHCP server have 5 pools. One pool for VLAN.  You need read basic documentation about networks. 


In CLI enter commands:

show run


show vlan

and post result there


And draw network diagram you use

Cisco Employee

Re: Creating new VLAN on SG300


Regarding problem 1, the firmware version on the Switch is very old ( So you need to upgrade the latest firmware and boot code on the SG300 Switch. Please follow the below mentioned link to download the latest firmware for your respective SG300 Switch model…

Also, you may follow the below mentioned link to upgrade the firmware and boot code on the Switch…

Once you will upgrade the firmware, accordingly you will get the CLI prompt to enter commands.

Note: In case you need any assistance to upgrade the firmware on the Switch then please feel free to contact us following the below mentioned link…


Regarding problem 2, DHCP process will take care about that part, you need to make sure the DHCP server / DHCP relay & Trunk links are configured properly. And Switch ports are assigned with different VLANs based on the user requirement. You may read about DHCP process to get more details.