How to Enable Ports 25 - 28 on a Cisco Catalyst 3750

I am trying to enable ports 25 - 28 on my 28 port Catalyst 3750. These four ports are my fiber ports. I am using the following command to bring up that interface.

interface range Gi1/0/25 - 28

That works and it dumps me in the config-if-interface prompt. This is where I get stuck. I just want to enable these four ports and have them be in VLAN1 and On just like ports 1 - 24.

How do I do this?

From serverfault Jared Brown

• First of all, do a show running-config interface GigabitEthernet 1/0/X and have a look at how those interfaces are actually configured.

  Then do what is needed:

  • If they are in shutdown state, issue a no shutdown command.
  • If they are not in the right VLAN, issue a switchport access vlan X command.
  • If they are configured for something else than standard access (i.e. trunking), clear their configuration and reconfigure them.
  Webs : Could also do "sh int status" for a quick view look at all interfaces. But Massimo hit the nail on the head with his answer.

  Jared Brown : I issued a "no shutdown" to the interface range Gi1/0/25 - 28. Although when I back out to the non-enabled prompt and do a "show interface Gi1/0/25" the output states that Gigabit ethernet 1/0/25 is down, line protocol is down (not connected)". Ports 25 - 28 are still not connected.

  James Sneeringer : This may be a silly question, but are they actually connected to something? The fact that they say "down" and not "administratively down" means they are enabled. The switch just doesn't see anything connected to them. Do you have SFP modules inserted? The output of `show int Gi1/0/25` (or 26-28) should have a line showing the media type, such as `media type is SX`, or `media type is Not Present` if there is no SFP module installed.

  Massimo : Agreed. "Line protocol is down" states clearly that the switch thinks there isn't anything connected to those interfaces, so you should have a look at cabling and at whatever is at the other end.
  From Massimo

• Do the ports require GBICs (and, if so, do you have GBICs installed)? Do you have cables attached to the ports? If you're using fibre, you MAY have to swap the connectors around (I don't think this is possible for SFP connectors, so you'd have to have a cross-over cable or a connector that allows you to connect RX on one cable to TX on the other).

  Massimo : You've got quite confused ideas, haven't you?

  Vatine : Not necessarily. Off-hand, I don't recall if ports 25-28 require GBICs or not (if they're GBIC ports, they'll just be slots in the chassis). I guess I could check it, but... Missing cables happen, a lot, especially when different people deal with the physical install and configuration. Fibres being the wrong way around is painfully common.
  From Vatine