routing B/w router and switch

[rys]

Dear friends,

I have a requirement to connect a router to a switch with new vlan, sounds easy, rite?

My problem is, the router dont have any L3 ports,(Gi0/0 and Gi0/1) are connected to other routers.

Only available Spare port is L2 (Fa0/0/0-3). Of this Fa0/0/0 is already connected to the switch with a Vlan.

I assign a new Vlan on the Router and assigned an IP and  spare L2 port to it, and the at the switch side also.

I think of router on stick, but the router dont have any sapre L3 port.

My concern is, is there any way to connect between the router and swithc using the existing cable,

(without connecting a new cable b/w the Router and Switch for the new vlan).

Appreciate your responses.

Thanks

Riyas

[cadet alain]

Hi,

if your existing link is an access port then you'll have to use another access link on another port but if you have a trunk between the L2 interface of router and the switch then you can use one link only for all vlans.

Regards

Alain

Don't forget to rate helpful posts.

[rys]

HI Alain,

Thanks for your response. Unfortunately the existing link is configured as access port at switch side and the corresponding Vlan in the Router Port.

If I change my Switch port to trunk, Will it work ?? Any configuration needed at the router side ??

Because the Existing Fa0/0/0 and the new port Fa0/0/1 in the Router are in diffrerent Vlans.

Thanks

Riyas Rasheed

[Reza Sharifi]

Hi,

If you trunk the switch side, you need to do the same on the router. As soon as you change the switch from access to trunk, you will loose connectivity between the two devices until you do the same on the router.

HTH

[Bilal Nawaz]

Hello, sounds like you need to configure router on a stick using one or both of your gigabit ports

(not sure if you can port channel both gigabit ports and create sub interfaces on the Po interface - this would give you 2gb uplink)

http://www.cisco.com/en/US/tech/tk389/tk815/technologies_configuration_example09186a00800949fd.shtml

When you assign vlans to different things as you have mentioned, you can trunk from the switch, but you will have to trunk from the router.

The only way of doing that is by creating sub-interfaces and encapsulating it in dot1q with the correct vlan tag.

Hope this helps

Sent from Cisco Technical Support iPhone App

[rys]

Inorder to create subinterface, it shoule be an L3 port, right...here i can configure an IP address on a vlan interface only...

[Bilal Nawaz]

Oh sorry, I misunderstood, I was talking about using your existing GE routed ports? Are we not able to use these?

Are you able to create a trunk on any one of those 4 switched ports? At layer 2. Not sure about it but I know you can with NM16ESW module or something similar. Then I guess you could have vlan interfaces.

Sent from Cisco Technical Support iPhone App

[johnlloyd_13]

hi,

what router platform are you currently using?

is there a spare module slot to add on a L3 port?

[rys]

its a 2811 router,2 FE ports and 4 Port FE switch.

[sajid_m123]

If Fa0/0/0 of router is already connected to switch and you like to use this link for multiple vlans then you should be able to make that link as trunk and permit required vlans, and create interface vlan# on router and assign IP addresses to them.

You can have config written in notepad for both devices and just copy and paste on both ends to reduce downtime.

[rys]

Dear All,

Thanks alot for your valuable suggestions,,,

I want to give a try by trunking both the Router and switch port,So all vlans can pass thru..

I have another question,,

how abt configuring a secondary IP in the existing Vlan for the new Segment and a static route to direct the traffic ??