Figure 15: Cabling Qsfp+ Ports 17 And 21 For A Stack Trunk - Allied Telesis AT-x550-18XTQ Installation Manual


Caution
The switches will not form a stack if the connections do not cross
over to different QSFP+ ports, but will instead operate as
stand-alone devices.  E78
Stack of Two Switches
Stack of Three
The cables of 40Gbps QSFP+ stack trunks must cross over to
different slots 17 and 21 on the switches. That is, the connection of
the transceiver in slot 17 must connect to the transceiver in slot 21
in the next switch. Figure 15 shows the correct wiring
configurations for stacks of two, three, and four switches.
Figure 15. Cabling QSFP+ Ports 17 and 21 for a Stack Trunk
x550 Series Installation Guide for Virtual Chassis Stacking
Stack of Four Switches
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