S2700 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.
For stacking-supported service ports, some of them can be used as stack ports, whereas some can be used as ordinary service ports.
After a UCL group is created using the ucl-group command on S2720-EI switches, a stack cannot be set up.
Since V200R011C10, S2720-EI and S2750-EI series switches can set up stacks in service port stacking mode using dedicated stack cables.
The number of S2750-EIs used to set up a stack is recommended to be 2 to 5.
For S2700-EIs and S2710-SIs, if the stack system works only in Layer 2 and Layer 3 forwarding scenarios, the number of stack member switches is recommended to be 2 to 5. If the stack system works in user access or gateway scenarios that require protocol interaction, the number of stack member switches is recommended to be 2 or 3.
The S2720-EI has only one model, S2720-28TP-EI-AC, in V200R006C10, V200R009C00, and V200R010C00. The S2720-28TP-EI-AC cannot be upgraded to V200R011C00 and later versions. The number of S2720-28TP-EI-ACs used to set up a stack is recommended to be 2 to 5. In V200R011C10 and later versions, the number of S2720-EIs used to set up a stack 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
S2700-EI	First two GE ports on the front panel	1.5 m SFP stack cable	2.5 Gbit/s	Among S2700-EI switches, only the S2700-52P-EI-AC and S2700-52P-PWR-EI support the stacking function. A stack can be set up between the S2700-52P-EI-AC and S2700-52P-PWR-EI. A switch supports a maximum of two logical stack ports, and each logical stack port contains one stack member port. A switch supports a maximum of two stack member ports.
S2710-SI	First two GE ports on the front panel	1.5 m SFP stack cable	2.5 Gbit/s	Any models of the S2710-SI series can set up a stack. A switch supports a maximum of two logical stack ports, and each logical stack port contains one stack member port. A switch supports a maximum of two stack member ports.
S2720-EI	Two or four SFP optical ports	1 m passive SFP+ copper cables 3 m and 5 m passive SFP+ copper cables (supported in V200R011C10 and later versions) 10 m active SFP+ copper cable 3 m and 10 m AOC cables 6GE stack optical module (SFP-6GE-LR) and optical fiber 0.5 m and 1.5 m SFP+ dedicated stack cable (supported in V200R011C10 and later versions)	2.5 Gbit/s	Any models of the S2720-EI series can set up a stack. A switch supports a maximum of two logical stack ports, and each logical stack port contains one or two stack member ports. A switch supports a maximum of four stack member ports.
S2750-EI	Two SFP optical ports	1 m SFP+ passive high-speed copper cables 10 m SFP+ active high-speed copper cables 3 m and 10 m AOC cables 6GE stack optical module (SFP-6GE-LR) and optical fiber 0.5 m and 1.5 m SFP+ dedicated stack cables (supported in V200R011C10 and later versions)	2.5 Gbit/s	Any models of the S2750-EI series can set up a stack. On an S2750-EI switch, only the first and second service ports from the right can be configured as stack member ports of a logical stack port. A switch supports a maximum of two logical stack ports, and each logical stack port contains one or two stack member ports. Each switch can use a maximum of two service ports as stack member ports.