Most or all of the ports are connected to a desktop or server.  Because this was a live system with a lot of users I was trying to migrate them to a (non-default) vlan without disruption.  I realised after reading a post on this forum that  the vlan associations was definitely not what I wanted.  associations as I understand it now lets the switch put a machine in a vlan based on its IP.   I came in after hours and moved all ports to access mode and vlan 192 which is my first step.  The problem was that I had to do it all at once to maintain connectivity.  Even then I forgot to move the LAG as well.  Once I did that as well the subnet works correctly. If I want multicast routing without unicast routing is that possible?
I have a stack of 6248s.  They are in production.  They were configured when I got them with a very basic config.  I can include it.  Essentially the IP of the switch was in the Default vlan.  I need to break the ports into a number of vlans and use the switch to route.  I need to do this without breaking anything.  So far I have created the VLANs and moved everyone from the default vlan by the process of turning all the ports to general mode and adding the new vlan to each port. interface ethernet 1/g2switchport mode generalswitchport general allowed vlan add 192exit! When I first did this it had a tendency to broadcast lots of traffic and I couldn't ping between hosts so I added an association:  vlan routing 2 1vlan routing 10 2vlan routing 20 3vlan routing 30 4vlan routing 200 5vlan routing 192 6vlan association subnet 192.168.2.0 255.255.255.0 192vlan association subnet 192.168.10.0 255.255.255.0 192exit With all ports configured like this everything works. The problem is that when I change a port to this: interface ethernet 1/g40switchport access vlan 192exit! Then the PC can see everything on the subnet but can't access anything else. I will add the configs as a reply. Edited: I would like to convert most ports to access mode.  For the current working VLAN which is VLAN 192 the switchs don't need to do any routing.  For the other VLANs the switchs will route.  Even now if I remove the "routing" command from VLAN 192 a machine on a port set to access mode seems to lose all connectivity.
VLAN routing problem