if I use 4 cat6 utp cables to connect one 2960G to 3650G per access switch and repeat this for other 4 remaining access switches
Can I use gigabit etherchannel to make a 4G connection between access and core switch? So far I have mixed replies: One says yes but core switch has bottle head (A) One says no, the maximum bandwidth between access and core for these module is only 1G (B)
Technically, this will work and you will have 5, 4 gig etherchannels. Your issue is more on switch backplane and performance. I don't deal with the smaller switches too much, but using a 6148 blade for a 6500 as an example, each segment of 8 ports shares an ASIC behind the scenes. Each ASIC is only rated at 1 gigabit, meaning that if you did two four gig ethernchannels or 4 two gig etherchannels, the maximum throughput is still only 1 gig. Each of the 2 four gig channels would only get 500 megabit if running full throttle. While I don't know the make-up of the 2960s or 3560s, both sides are likely to have similar constraints. Even if the 3560 can support 4 gigs on consecutive ports, can the 2950? If you stagger out the ports so each channel has one port in 1-7, 8-15, and 16-23, you may be able to get 3-4 gigs on a channel to one switch at a time, but multiple channels will cannibalize any common hardware thresholds.
The point is, I would consider getting two 3560s, and doing a gig or two from each to each 2960. This is much better for redundancy, would allow you to have layer 3 redundancy with HSRP, and spreads your usage out. I would also either split your vlans even/odd across the two
3560s, or distribute the vlans out to the 2960s if they support layer
Just my two cents.
Perhaps someone else can speak to actual hardware thresholds on these models...