Network topology consists of 3 buildings(Two 6509 & 4500).
HSRP is running between the Core 6500 switches.
Existing topology is using native VLAN 1(10.1.1.0/24) for all dot1q trunks.
Plan is to introduce Layer 3 switching for the DATA and Voice VLAN with the 3 core switches configured as the default gateway.
Each core switch will have a unique DATA and VOICE VLAN for layer3 switching.
At the same time I can still use the Layer 2 VLANs (VLAN 1 & 100) on all switches in the campus
EIGRP protocol will run between all core switches.
A layer 2 and layer 3 link will be connected between all 3 Core switches (Diagram)
Please comment/advise on network. Will this solution be possible?
I suggest to manually configure the set of allowed Vlans on each trunk on a per link basis on the long term is better because VTP pruning doesn't stop STP frames so if you allow all vlans on all trunks the topology for each vlan can include links that can be excluded once for all by using the trunk allowed command.
You need the network command also for the "L2" subnets in case the local L3 switch misses its link to them it can reach via the other devices.
Hope to help