The Inter-Switch Link Protocol (ISLP) is the proprietary VSX control-plane mechanism used across the VSX Inter-Switch Link to synchronize operational state between the two VSX peers. HPE Aruba Networking specifically documents that each VSX node performs periodic synchronization every second through ISLP , including learned MAC addresses, LACP states , and spanning-tree state information. Therefore, option D directly describes a documented ISLP function. Aruba Networks
LACP synchronization is particularly important for VSX LAGs . Both VSX peers must maintain coordinated LACP state so that a downstream device sees the two physical switches as a consistent multichassis aggregation endpoint. During VSX recovery, ISLP is also used to restore LACP, MAC, ARP, and spanning-tree databases before affected VSX LAGs are returned to normal forwarding. Aruba Networks
Option A confuses the ISL with the keepalive path . The keepalive is a separate Layer 3 mechanism whose primary function is peer-liveness detection during an ISL failure; it is not the channel used for normal ISLP state synchronization. Aruba Networks Option B is incorrect because the ISL itself is a Layer 2 interface/LAG and does not require a routed-only port. Although RPVST is supported with VSX, Aruba ' s documented permanent synchronization examples explicitly identify LACP and MSTP/STP state synchronization , making D the precise answer. Aruba Networks
Study Guide References: VSX ISLP; Inter-Switch Link; Periodic Synchronization; LACP State Synchronization; VSX LAGs; Keepalive.
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