Redundant link between to L3 switches

If you absolutely must have the same L3 networks available in both locations, then you don't really have a lot of choice. However this creates long convergence times (spanning-tree), and requires a lot of maintenance. I would generally avoid this at all costs unless you have specific requirements. Using a nice L3 design with a summarized address space and two links is much cleaner and much faster in terms of failover. While neither solution may work completely uninterrupted, a OSPF or EIGRP solution could easily reconverge while only needing to re-establish application sessions. Bring both links up in eigrp, eigrp will automatically prefer the higher bandwidth path, and if/when it fails, it will route over the backup path. Just ensure you have an adjacency on both links, and you architect l3 properly. Just my 2 cents....

Not sure what you were trying to say "If you absolutely must have the same L3 networks available in both locations" please elaborate Thank you very much

Do you need the same subnet available in both locations (i.e.

10.0.0.0/24 or something similar)? If so, then you will need to architect a solution that puts the same subnet (i.e. vlan) in both locations. This limits your options to trunking or something similar. If you don't need the same l3 network in both location, then create new subnets in the 2nd facility, summarize them together, and advertise them back to the main office. That way each office has two paths to the other's l3 networks, and can failover as necessary in the event of an issue. Unless you absolutely have a requirement for two boxes (one at each location) to be in the same L3 subnet (private vlans for oracle or load balancing servers can drive this type of requirement), I would avoid a l2 based solution.

Thank you very much