Which OTV failure isolation feature ensures that BPDUs are not forwarded across the overlay?
- ARP optimization
- unknown unicast handling
- STP isolation
- broadcast policy control
Overlay Transport Virtualization (OTV)’s Spanning Tree Protocol (STP) isolation feature ensures that bridge protocol data units (BPDUs) are not forwarded across the overlay. This feature is enabled by default. Because BPDUs are suppressed, each data center’s STP domain remains independent of other data centers connected to the overlay. This prevents data centers from accidentally creating Open System Interconnection (OSI) networking model Layer 2 loops over OTV.
OTV is a technology that extends Layer 2 networks across data centers. Similar to Ethernet over Multiprotocol Label Switching (EoMPLS), virtual private LAN services (VPLS), and dark fiber, OTV is intended to enable the extension of Layer 2applications across large geographic distances. It is typically deployed on data center edge devices. OTV used Media Access Control (MAC) address routing to ensure that Layer 2 reachability information can be transmitted between data centers. Unlike other Layer 2 extension technologies, OTV’s MAC address routing takes place at the control plane level. Other technologies rely on data plane forwarding and flooding,
OTV’s unknown unicast handling feature maps a MAC address from a remote data center to that data center’s join interface Internet Protocol (IP) address. The join interface is the Layer 3 interface on which OTV is deployed and that is capable of discovering other OTV-enabled data centers. OTV’s unicast traffic handling feature advertises MAC addresses between data centers. Because of this advertisement and mapping process, OTV is capable of suppressing the transmission of unknown unicast traffic across data centers.
Broadcast policy control and Address Resolution Protocol (ARP) optimization are OTV features that reduce traffic between OTV-connected data centers. Each of these features reduces the amount of broadcast traffic that is flooded between data centers.