Because my routers only have a single eth interface each, I would like to set up subinterfaces for each one (one for my inside network, one for my outside network). Also, I would like to set up HSRP for my subinterfaces between routers. Since I can't add IP addresses to my subinterfaces without a higher-level IOS, I've ordered full mem upgrades for both. My question is, will my idea work? When I add IP addresses to the subinterfaces right now, I get an error telling me that the main interface has to be set for ISL or dotq. Simple enough, the upgrades will let me do that. But adding those settings to the main interface is usually done when you want to do inter-vlan routing, no? Why would it matter if you're not routing between vlans?