S6720-HI 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.
For stacking-supported service ports, some of them can be used as stack ports, whereas some can be used as ordinary service ports.
The first 12 10GE ports of the S6720-50L-HI-48S cannot be used as stack member ports.
S6720-HI series switches of all versions 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-HI	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	10 Gbit/s	Any models of the S6720-HI series can set up a stack. Two types of ports on an S6720-HI can both be configured as stack member ports, but each logical stack port contains only the same type of stack member 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. When 40GE 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 six stack member ports. Each switch can use a maximum of six service ports as stack member ports. When 100GE 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 a maximum of two stack member ports. Each switch can use a maximum of two service ports as stack member ports. Only the last 16 10GE ports on the front panel can be used to set up a stack using dedicated stack cables. 40GE ports do not support the stacking function after they are split into 10GE ports. When 100GE ports are used as stack member ports and are connected using 1 m, 3 m, and 5 m QSFP+ passive cables or QSFP+ optical modules and fibers, you can run the stack port speed command to reduce their working speed from 100 Gbit/s to 40 Gbit/s. After their working speed is reduced to 40 Gbit/s, switches using these ports can set up a stack with switches using ports working at 40 Gbit/s and cannot set up a stack with switches using ports working at 100 Gbit/s.
	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
	100GE ports on the front panel	1 m, 3 m, and 5 m QSFP28 high-speed copper cables 10 m QSFP28 AOC cables QSFP28 optical module and optical fiber	100Gbit/s