I have a Cisco 3550 Switch (with an EMI) image. I seem to be stuck trying to figure out if the switch has a possibility of setting IP addresses (i thought Layer 3 switches could do that). I want to set up a vlan for specific ports in my lab and then use the switch to relay DHCP requests out a specific port.

FA 0/1 --- I want to be the default port / thing everything communicates between the router (not using a cisco router right now so i cannot set up a trunk port etc)

I want Fa0/23 to be configured to get DHCP address from router through fa0/1 (will my switch know that? or time out? It seems to take longer than if i plugged directly into the back of my router.


  • What are your subnet configurations? You want Fa0/23 to get a DHCP address or do you rather want what is plugged in Fa0/23 to get a DHCP address? You'll have to refine your question with more details on your network setup. I can give you many ways to do that but they all depend on what is what and what sub-net, what routes where, etc. – ETL Apr 28 '13 at 13:50

You can setup a VLAN and have your switch receive DHCP packets through there.

interface Vlan12
 ip address
 ip helper-address

The ip helper-address will broadcast DHCP request to your router.

Then setup your interfaces on that VLAN.

interface FastEthernet0/23
switch port access vlan12
switch mode trunk
  • -sorry for delayed response have been busy with work and placed my studies aside - But in regards to your answer, do I have to set up "router on a stick" vlan configuration to set up a trunk mode on port? Or can I just have vlans exist within the switch and router not know about it? – Bain May 26 '13 at 15:54

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