When interconnecting an upstream network tier with an ArubaOS-CX Virtual Switching Extension (VSX) aggregation/core pair, multi-chassis link aggregation (VSX LAG) must be architected from the perspective of the attached peer systems.

In this topology, the two campus core switches operate as individual devices or separate entities requiring redundant connectivity into the data center core VSX pair. A VSX LAG enables both data center core switches to act as a single logical LACP aggregation partner toward a downstream or upstream device.

To form a valid IEEE 802.3ad LACP port-channel, all physical links within a single link aggregation group must terminate on the same logical entity at both ends. Campus Core Switch 1 has two physical links into the data center core: Link 1 (to Data Center Core 1) and Link 2 (to Data Center Core 2). These two links must be bundled together into a single VSX LAG. Similarly, Campus Core Switch 2 connects via Link 3 (to Data Center Core 1) and Link 4 (to Data Center Core 2), which must be bundled together into a separate, second VSX LAG. This design provides loop-free, active-active Layer 2 trunking without spanning-tree port blocking.

Reference Topics: HPE ArubaOS-CX VSX Architecture – Upstream and Downstream Multi-Chassis Link Aggregation (VSX LAG) Cabling and Port-Channel Grouping.

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