Exhibit.LAG and MCLAG are used to increase the available network bandwidth and enable redundancy. How does spanning tree protocol see MCLAG and LAG…

In a Multichassis Link Aggregation (MCLAG) architecture, the two peer switches (Switch 1 and Switch 2) synchronize their forwarding states to present themselves as a single, unified logical switch to downstream devices and the Spanning Tree Protocol (STP). This abstraction prevents STP from recognizing a physical loop and blocking the redundant links. Consequently, the aggregated links from Switch 3 connecting to the Switch 1/Switch 2 peer group are treated by STP as a single logical interface. Similarly, the standard Link Aggregation Group (LAG) between Switch 3 and Switch 4 bundles multiple physical connections, meaning STP also views Switch 4's uplinks as a single logical interface.

Option A: Switch 1 and Switch 2 form the MCLAG peer group. Switch 3 is a downstream client, not a member of the peer group itself.

Option C: Switch 3 is the only MCLAG client. Switch 4 connects to Switch 3 via a standard LAG, not as part of a unified MCLAG client.

Juniper Networks. "Understanding Multichassis Link Aggregation Groups." Junos OS High Availability Feature Guide. Section: MC-LAG and Spanning Tree Protocol Interactions.

IEEE Computer Society. (2014). "IEEE Standard for Local and metropolitan area networks -- Link Aggregation." IEEE Std 802.1AX-2014, Section 5.3 (Link Aggregation functioning as a single MAC client), pp. 17-20. DOI: 10.1109/IEEESTD.2014.7050029.

Arista Networks. "Multi-Chassis Link Aggregation (MLAG)." Arista EOS User Manual, Chapter 14: Spanning Tree Protocol and MLAG Topology, pp. 412-415.