I have 3 COM (3CR17561 layer 3) 26 port PoE. I have connected this 3COM switch with router 1750. I used vlan on 3COM and direct connected with cisco 1750. Can any one help me how to configure vlan trunking in 3COM 3CR17561 so any router beside Cisco 1750 can ping to all subnet in that 3COM.