Cisco 3020 with FastEthernet0 and VLAN IP addresses

[Paul.Kraus]

A Cisco 3020 running IOS 12.2(52)SE has IP addresses assigned to the FastEthernet0 and to a VLAN interface "vlanb" in two different subnets. The switch is not running a routing protocol. The OA/iLO interface is connected to an external switch in VLANa and an uplink is connected to an extenal switch in VLANb corresponding to the subnet of the switch VLAN interface "vlanb" mentioned above. An ip default-gateway is defined on the 3020 pointing to the gateway address of VLANb.

A PC is connected to external switch in VLANc. A layer3 swtich provides routing between VLANa, VLANb, and VLANc. It is possible to connect to the 3020 from the PC in VLANc using the 3020's VLANb ip address. However, it is not possible to connect to the same 3020 from the PC using the 3020's ip address in VLANa (via OA/iLO). The PC can access the OA and other iLOs in the chassis, so connectivity through the OA port is ok.

Is there some logic in the 3020 that prevents switch management traffic with the FastEthernet0 ip address from exiting the switch on one of the uplinks?

There could be a filter somewhere in the external network preventing this traffic, but before investigating futher, I would like to know if it should be possible to manage a 3020 switch from both the FastEthernet0 interface and a VLAN interface, or if this is an unsupported configuration.