FabricPath Switch ID Assignment
Question
In a FabricPath topology, each device is identified by a switch ID, and all Layer 2 forwarding tables are built based on the reachability of the switch ID.
Which protocol is used to assign the switch ID?
Answers
Explanations
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A. B. C. D.B.
FabricPath is a Cisco proprietary technology that provides Layer 2 multipathing, similar to Virtual Port Channel (vPC), but with several improvements. One of the features of FabricPath is that each device in the topology is identified by a unique switch ID. This switch ID is used by all devices in the FabricPath network to build Layer 2 forwarding tables, which enable efficient forwarding of traffic across the network.
To answer the question, the protocol used to assign the switch ID in FabricPath is option D: The switch ID is assigned based on the system ID of the device.
The switch ID is a 16-bit value that is unique to each device in the FabricPath network. It is constructed by combining a system ID, which is assigned to the device, with a local ID, which is assigned locally by the device. The system ID is a 10-bit value that is assigned by the network administrator or automatically generated by the device using a process known as the "Unique ID Distribution Protocol" (UDLD).
UDLD is a protocol used by Cisco devices to detect and disable unidirectional links, which can cause network loops and other problems. When a device boots up or detects a change in its network topology, it sends out a UDLD packet to its neighbors. If a neighbor responds with a matching UDLD packet, the link is considered bidirectional and normal operation can proceed. If the neighbor does not respond, the link is considered unidirectional and is disabled.
When UDLD is used to automatically generate system IDs for FabricPath devices, each device generates a unique system ID based on its UDLD packets. The system ID is then combined with a local ID to create the switch ID.
In summary, FabricPath uses the system ID of the device, which can be assigned manually or automatically using UDLD, to create a unique switch ID for each device in the network. This switch ID is used by all devices in the FabricPath network to build Layer 2 forwarding tables, enabling efficient forwarding of traffic across the network.
