VLAN issue...easy question...just confusing to me

bmoorewiz · ‎09-30-2007

I have a 2900 cisco switch. I have a domain with 4 computers setup, and they are all on vlan 1 the native of course. I am trying to add a 5th but I want it to be on vlan 2. My only route out is my linksys wireless router which then goes out through a cable modem. But it seems that only 1 vlan can be up at one time....I dont understand this....can someone please help me.

I thank you in advance for your help...

-Brandon...taking the CCNA teusday.

Richard Burts · ‎09-30-2007

Brandon

I believe that what you are missing is an understanding of the difference between an access port and a trunk port. Based on the explanation which you provide I believe that the port which connects your 2900 switch to the Linksys is an access port in VLAN 1. This will pass VLAN 1 traffic but will not pass VLAN 2 traffic.

If you want to pass both VLANs over a port then you need to configure that port as a trunk port. However if you configure the port on the 2900 as a trunk, that will depend on the Linksys understanding a trunk port in which traffic from VLAN 2 will be tagged with VLAN information. I am not at all sure that the Linksys will process VLAN tagged traffic.

HTH

Rick

HTH

Rick

JORGE RODRIGUEZ · ‎09-30-2007

Brandon, if you are trying to create another subnet when creating vlan 2 there would a problem routing that second subnet through the linksys as this routers only support a single subnet in your local LAN. Yes you can create as many vlans you want on the 2900 series switches but these switches are only layer 2 switches , you would need a real router in order to do inter vlan routing.

If this is not what you are intending to do could you explain what are you trying to accomplish by creating VLAN2 .

For Example, lets assume you need a second and 3rd subnet by creating vlan2 vlan3 etc..

your setup would be:

SW2900-ROUTER-LINKSYS-CABLEMODEM-->>to internet

the router before linksys would do your inter vlan routing, and ROUTER will have LinkSys as its default route so all subnets can get out to internet.

HTH

Jorge

Jorge Rodriguez

bmoorewiz · ‎09-30-2007

Thanks for your responses...that helped...I already had the port set as a trunk...but it still didnt work...But I really appreciate your help

Thanks Guys

-Brandon

bmoorewiz · ‎09-30-2007

One more thing, That still does not explain why my VLAN is in a Down and Down state?

Why can only 1 VLAN be up at one time?

Richard Burts · ‎09-30-2007

Brandon

It is one of the characteristics of being a layer 2 switch. A layer 2 switch has a VLAN interface for management access.

I believe that it is helpful to understand the difference between having multiple VLANs and having multiple VLAN interfaces. A layer 2 switch can have multiple VLANs and can forward traffic on each VLAN because each VLAN operates at layer 2. A VLAN interface is a layer 3 interface. A layer 2 switch can have one but only one layer 3 interface active to provide management access.

HTH

Rick

HTH

Rick

paul.matthews · ‎10-01-2007

the 2900 is a L2 switch - it can only have one VLAN interfave active at anyone time. It can carry multiple VLANs, but you need a router or L3 switch to get traffic from VLAN1 to VLAN2.