I'm already pretty certain this is impossible, but it's at least the second time I've found myself in this situation and really wishing it could be done, so if for no other reason than to save others the time I've spent in the past looking at this...
I'm using a Cisco PIX 515E with fairly recent 8.0x software with an Unrestricted license and a single 4-port HWIC card.
I'm currently a little short on switch ports at the PIX's physical location, but only one of the HWIC ports is currently in use, and the servers I need to drop into the location won't have enough traffic to be concerned about.
That being the case, I'd really love to be able to bridge a couple of the unused ports onto one of my existing VLANs, but the PIX doesn't seem to like that idea at all:
pixfirewall(config-subif)# vlan 1200 ERROR: VLAN 1200 has been assigned to another interface pixfirewall(config-subif)#
Short of setting up a new VLAN and subnet and creating the appropriate rules to pass traffic (an unpleasant prospect in this case, not least because of a reliance on DHCP and other broadcast traffic), is there any way to accomplish what I'm after?