Your customer has an Aruba CX 6200F VSF stack with two switches.

According to the Aruba Documentation Portal 1 , the Aruba CX 6200F VSF stack is a feature that allows you to create a virtual switching framework (VSF) with up to eight members that can be managed as a single logical device. The VSF stack provides benefits such as load balancing, failover, redundancy, and security.

To add a new device to the VSF stack, you need to configure the device with the VSF command  vsf member  and specify the type, link, and secondary-member information. The type of the new device can be one of the following:  JL726A ,  JL726B ,  JL726C , or  JL726D . The link is the interface that connects the new device to the existing VSF members. The secondary-member is an optional parameter that specifies which member will act as a backup in case of a failure.

1 : https://www.arubanetworks.com/techdocs/AOS-CX/10.06/HTML/5200-7726/index.html  2 : https://buy.hpe.com/us/en/networking/switches/fixed-port-l3-managed-ethernet-switches/6000-switch-products/aruba-6200f-48g-4sfp-switch/p/jl726a  3 : https://addin.co.th/shop/switch/aruba-switch/6200f-series/jl726a/