Solved: Enable Routing and Trunks

mvelasco2 · ‎08-22-2013

Hi,

I have a remote network which I manage with 2-3560 switches and just the default vlan. I need to add multiple vlans so I will need to enable routing and trunk the uplink ports between switches. Can I safely enable routing and trunk the uplink ports without losing access to the switches? I know I will have to add the default route on switch where I enable routing. My concern is that I may lose access to the switches during one of these operations.

Thanks,

Marlon

Richard Burts · ‎08-25-2013

Marlon

You are correct that now the switches are using default-gateway to send traffic to destinations that are outside of their local subnet/vlan. And that when you enable routing that the default-gateway command will no longer have an effect. So if you are connected to these switches from a remote subnet then your connection may fail when you enable routing.

Is there a device with layer 3 capability that is connected to these switches in their local subnet/vlan? If so then I suggest that you establish a session to this layer 3 device. And from that device establish sessions to the individual switches. Then you can enable routing, configure default routes, and configure trunking. And as long as you do not change things in the current vlan then your connection should not be impacted while you make the routing and trunking changes.

Let me try to explain it from a slightly different perspective. As long as the current vlan continues to have the same connections, and as long as it becomes the native vlan when you enable trunking, then it will continue to send untagged frames as the native vlan when you enable trunking and continue to work. And as long as your connection to the switches is from a device that is in the same subnet/vlan then it does not matter whether the switches are using default-gateway or routing as far as communication for your sessions is concerned.

HTH

Rick

HTH

Rick

View solution in original post

Richard Burts · ‎08-25-2013

Marlon

You are correct that now the switches are using default-gateway to send traffic to destinations that are outside of their local subnet/vlan. And that when you enable routing that the default-gateway command will no longer have an effect. So if you are connected to these switches from a remote subnet then your connection may fail when you enable routing.

Is there a device with layer 3 capability that is connected to these switches in their local subnet/vlan? If so then I suggest that you establish a session to this layer 3 device. And from that device establish sessions to the individual switches. Then you can enable routing, configure default routes, and configure trunking. And as long as you do not change things in the current vlan then your connection should not be impacted while you make the routing and trunking changes.

Let me try to explain it from a slightly different perspective. As long as the current vlan continues to have the same connections, and as long as it becomes the native vlan when you enable trunking, then it will continue to send untagged frames as the native vlan when you enable trunking and continue to work. And as long as your connection to the switches is from a device that is in the same subnet/vlan then it does not matter whether the switches are using default-gateway or routing as far as communication for your sessions is concerned.

HTH

Rick

HTH

Rick

mvelasco2 · ‎08-28-2013

Thanks for the clear explanation Richard, worked like a charm!

Thanks.

Richard Burts · ‎08-28-2013

Marlon

I am glad that my explanation was helpful and that you feel that it did answer your question. Thank you for using the rating system to mark this question as answered. It makes the forum more useful when people can read a question and can know that an answer was found. Your marking has contributed to this process.

HTH

Rick

HTH

Rick