Abhijit,
The choice of the Core switch should be decided based upon many factors. Your port count at this point is 450. Are these coming directly into the core switch or they are spread out in wiring closets and wiring closet switches run fiber to the core ? If you need more port count on the core switch, then you need a bigger slot switch (9 slot or 13 slot).
Since the core has to be designed with reliability and high availability in mind, you would want atleast 2 SUP engines on the same chassis or get two chassis with one SUP each. Dual power supplies are also a good choice.
The backplane capacity of a 4507 is upto 64gbps, versus a 6509 can go upto 720 gbps (with a Sup 720). The question is how much bandwidth you need in the core to support all your wiring closets. Do a bandwidth analysis of how many uplinks you have from each wiring closet to the core, plus any additional FE or GE ports that are sending traffic directly to the core switch (directly attached devices). Add some buffer bandwidth to accomodate all your wan traffic driving through your core. As a rule of thumb, if the total adds up to more than 50 % of 64 gbps, I would go ahead and get a 6506 with Sup 720 as it will scale well enough to support extra modules added in the future.
HTH
PS: please remember to rate helpful replies!
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus
