Our company is considering adding a Cable connection to our 1721 Router to provide a redunant connection, as well as to provide an alternate route to a site or two we've been having traffic issues with (that, of course, is nobody's fault on our end, their end, or even the ISPs in the middle - I digress).
It's been a while since I had to do much of anything with our router. We already have a fully functional T-1, and of course, the FastEthernet to our firewall. It looks like there's an ethernet WAN interface option for the router that will interface with the cable modem, and I know enough to configure that to work with the cable provider.
My question is, what commands, if any, will I then need to utilizie to enable the cable connection to ask as an alternate route to the Internet? I'm fairly certain I'll be able to make a static map to the host that's giving us trouble (ip route a.b.c.d 255.255.255.255 eth 0), but since our T-1 is the default gateway, it seems like I'll need some other routing options to allow the 1721 to "pick and choose" which path is best for outbound traffic at any time.
Would this be the time for me to brush up on routing protocols? If I recall correctly those were more for "internal" routing - between connections I control.
Any information/thoughts/tips will be greatly appreciated.
I'll be happy to provide config snippets as requested (don't want to spam a ton of irrelevant config info here).