Building Loop-Free Topologies for Multidestination Traffic

A.

FabricPath is a Cisco proprietary technology that allows for the creation of large Layer 2 domains, which can be more scalable and efficient than traditional Spanning Tree Protocol (STP) based networks. One of the key benefits of FabricPath is its ability to build loop-free topologies for multidestination traffic.

Option A: FabricPath uses forwarding tags to ensure a loop-free topology. This option is correct. FabricPath uses a unique identifier, called the Switch ID (SID), to build loop-free topologies for multidestination traffic. Each FabricPath switch is assigned a SID, which is then used to generate forwarding tags for packets that traverse the FabricPath network. The forwarding tag includes the destination SID, which is used to determine the next-hop switch for the packet. FabricPath also uses a hash algorithm to load-balance traffic across multiple paths, ensuring that traffic is evenly distributed and preventing congestion.

Option B: FabricPath uses multicast groups to encapsulate Ethernet traffic in IP multicast packet. This option is incorrect. FabricPath does not use multicast groups to encapsulate Ethernet traffic in IP multicast packets. Instead, FabricPath uses a header format that is similar to the Ethernet header but includes additional fields to support the SID-based forwarding and load balancing.

Option C: FabricPath cannot have loops and does not need to rely on any logic to prevent them. This option is incorrect. Although FabricPath is designed to build loop-free topologies, it is still possible to create loops if the network is not properly configured. FabricPath uses a number of mechanisms to prevent loops, including SID-based forwarding, load balancing, and loop detection.

Option D: FabricPath uses spanning-tree inside the FabricPath network to prevent loops. This option is incorrect. FabricPath does not use the Spanning Tree Protocol (STP) inside the FabricPath network. Instead, it uses a combination of SID-based forwarding and loop detection to prevent loops.

In summary, FabricPath uses forwarding tags to ensure a loop-free topology for multidestination traffic. Each FabricPath switch is assigned a unique identifier, called the Switch ID (SID), which is used to generate forwarding tags for packets that traverse the FabricPath network. FabricPath also uses a hash algorithm to load-balance traffic across multiple paths and a loop detection mechanism to prevent loops.