High-availability requirements of virtualization technologies, the costs associated with deploying and maintaining a dedicated fiber network, and technology limitations have led to the development of Virtual Private LAN Service (VPLS)-based solutions. These solutions provide multipoint Layer 2 (L2) connectivity services across geographically dispersed data centers over a Layer 3 (L3) network infrastructure.
Key objectives for using L3 routing rather than L2 switching to interconnect data centers include the following:
• Resolve core link-quality problems using L3 routing technology
• Remove data center interdependence using spanning-tree isolation techniques
• Provide storm-propagation control ...