S5720-EI Stack Card Stacking Support

For the cables that can be used as stack cables, see "Cables" in the Hardware Description. Using other cables may cause exceptions in the stack system, for example, frequent error-down events on stack ports.
S5720-EI series switches are classified into S5720-C-EI, S5720-PC-EI, S5720-X-EI, and S5720-P-EI based on their uplink interface types.
In V200R009C00 and later versions, if MPLS-incapable S5720-EIs exist in a stack, this stack cannot have MPLS enabled. If member devices in a stack are running MPLS services, adding MPLS-incapable S5720-EIs to the stack is not allowed. To check whether S5720-EIs support MPLS, run the display device capability command.
The number of stacked switches is recommended to be 2 to 9.

**Table 1** Stack card stacking support
Device Series	Port Supporting Stacking	Stack Cable	Remarks
S5720-C-EI and S5720-PC-EI	Two ports on each ES5D21VST000 stack card	1 m, 3 m, 5 m QSFP+ passive high-speed cables QSFP+ optical module (only QSFP-40G-SR4 and QSFP-40G-iSR4 supported) and matching optical fiber	Any models of the S5720-EI series can set up a stack.
S5720-X-EI and S5720-P-EI	Two ports fixed on the rear panel	1 m, 3 m, 5 m QSFP+ passive high-speed cables QSFP+ optical module (only QSFP-40G-SR4 and QSFP-40G-iSR4 supported) and matching optical fiber	Any models of the S5720-EI series can set up a stack.