Here's my scenario: I have a two 6509's connected to 3 stacks of three 3750 switches, with 2 10G links per stack. The 10G links connect to the first and last switch in each stack. Each 10G link is a L3 point to point connection. I want to add a backup link to the middle switch in each stack, but I don't have any more 10G links available. I'm looking for feedback on my options.
I figure that my first option is to leave it alone, because I already have two links to each stack Just humor me on this and assume I need another link.
My second option is to use a 1G L3 link between 6500 and 3750, which would have the advantage of utilizing the rapid convergence inherent in dynamic routing protocols.
My third option is to use flex links, by moving the L3 interface to a vlan interface, and configuring the 1G interface as a backup to one of the 10G links.
I haven't seen much on here about people using flex-links -- can I assume that this would be the least preferred option?
Thanks in advance for the help -- all replies will be rated, so feel free to chime in.