I have a slight disagreement with my co-workers here. We are going to connect our corporate network to another company's network over dual 20mbs metro ethernet lines for redundancy. I think we should firewall it and route via BGP between our networks. We will treat them like a trusted extranet.
My colleague feels it's enough to firewall and NAT their network and we can use static routes pointing to them and etherchannel both ethernet ports.
What is the pro and cons of each scenario?