I need to replace existing core switch 4506 running CatOS with a 4507R-E running IOS and keeping existing trunks to 3550 L2 switches. The challenge I have is that since current ip traffic flows under default Vlan1 (management on switches too as interface Vlan1 with respective ip address) and default gateway is set for the WAN router on the same Vlan and segment, I was asked to not only create and assign an interface loopback with a different ip address to the new 4507 but remove all ports and management to a different Vlan number to start releasing Vlan 1 on this switch. My concern is how to achieve that without affecting communication to 3550s switches forward and backward the main router. I am not sure if just with the statement native Vlan X...on each on the trunks to the 3550s could work since the L3 is within the same ip scope. The 3550s swithces should be replaced eventually in the near future, but at this time the core swith is the one affected.
For the new ip address on the loopback interface, I will have to set an static route in the WAN router to be able to reach this and in the future the rest of the switches since there is no routing protocol running on the deployment.
I really appreciate your advice.
Francisco de la Rosa