Hi,
my name is Philipp Stadler, I'm a network security expert from austria.
Can you please specify what to you exactly mean by "centos based appliance"? - is it a centos installation with routing functionalities or is it a proprietary solution based on centos.
If it is real centos installation and you use standard trunking protocols (802.1q) then I will be able to configure trunking on your box with given bid.
regards,
Philipp