S6720-EI and S6720S-EI Service Port 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.
Combo ports cannot function as stack member ports.
Ports on the ES5D21X08S00 card of S6720-EI series switches cannot function as stack ports.
Since V200R011C10, S6720-EI and S6720S-EI series switches can set up stacks in service port stacking mode using dedicated stack cables.
The number of stacked switches is recommended to be 2 to 9.

**Table 1** Service port stacking support
Device Series	Port Supporting Stacking	Stack Cable	Rate of a Single Port	Remarks
S6720-EI	10GE ports on the front panel	1 m and 3 m SFP+ passive high-speed copper cables 5 m SFP+ passive high-speed copper cables (supported in V200R009C00 and later versions) 10 m SFP+ active high-speed copper cables 3 m and 10 m AOC cables 10GE SFP+ optical module and optical fiber 0.5 m and 1.5 m SFP+ dedicated stack cable (supported in V200R011C10 and later versions)	10 Gbit/s	A stack can be set up between S6720-EI and S6720S-EI if these switches use the same stack port types. That is, all of them either use 10GE ports or use 40GE ports. When 10GE ports on the front panel are used as stack ports, a switch supports a maximum of two logical stack ports, and each logical stack port supports at least one stack member port and at most eight stack member ports. A switch supports a maximum of 16 stack member ports. On an S6720-EI switch, when 40GE ports are used as stack member ports, a switch supports a maximum of two logical stack ports, and each logical stack port supports at least one stack member port and at most six stack member ports. Each switch can use a maximum of six service ports as stack member ports. On an S6720S-EI switch, when 40GE ports are used as stack member ports, a switch supports a maximum of two logical stack ports, and each logical stack port supports a maximum of two stack member ports. Each switch can use a maximum of two service ports as stack member ports. 40GE ports do not support the stacking function after they are split into 10GE ports. Only the last 16 10GE ports on the front panel can be used to set up a stack using dedicated stack cables. On the S6720-EI and S6720S-EI, every four of 10GE interfaces on the left are added to one group. For example, 10GE interfaces numbered 1 to 4 can be added to one group, but 10GE interfaces numbered 2 to 5 cannot. That is, the number of the last 10GE interface in each group must be the multiple of 4. If you configure any interface in each group as a physical member interface, configurations on the other three interfaces in the group will be lost and the three interfaces cannot be used as service ports.
	Ports on a 4-port 10GE rear interface card (supported in V200R019C00 and later versions)	1 m and 3 m SFP+ passive high-speed copper cables 5 m SFP+ passive high-speed copper cables 10 m SFP+ active high-speed copper cables 3 m and 10 m AOC cables 10GE SFP+ optical module and optical fiber	10 Gbit/s
	40GE ports on the front panel and Ports on a 4-port 40GE rear interface card	1 m, 3 m, and 5 m QSFP+ passive high-speed copper cables QSFP+ optical module and optical fiber (QSFP-40G-SR-BD optical modules can be used for stack since V200R019C10SPC500.) 10 m QSFP+ AOC cable (supported in V200R009C00 and later versions)	40 Gbit/s
S6720S-EI	10GE ports on the front panel	1 m, 3 m, and 5 m SFP+ passive high-speed copper cables 10 m SFP+ active high-speed copper cables 3 m and 10 m AOC cables 10GE SFP+ optical module and optical fiber 0.5 m and 1.5 m SFP+ dedicated stack cables (supported in V200R011C10 and later versions)	10 Gbit/s
S6720S-EI	40GE ports on the front panel	1 m, 3 m, and 5 m QSFP+ passive high-speed copper cables QSFP+ optical module and optical fiber (QSFP-40G-SR-BD optical modules can be used for stack since V200R019C10SPC500.) 10 m QSFP+ AOC cable	40 Gbit/s