It sounds as if you have a core 6509 switch, and 3550 access switches. I would reccomend thinking about configuring point-to-point ethernet connections between the 6509 and 3550 switches. Configure each 3550 as a seperate VTP domain, and setup the Access VLANs on the 3550. This will keep the broadcast traffic off the backbone, and breakup the huge broadcast domain. To gain access to the DHCP server, simply put an ip helper on the VLAN interface on the 3550. You will need to create the scopes on the server to match the Access VLANs on the 3550.
Also, you may want to change the duplex between the 6509 and 3550 to 100/full, or put a Gig link between the two.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...