S5721-28X-SI-24S-AC

Version Mapping

Table 1 lists the mapping between the S5721-28X-SI-24S-AC chassis and software versions.

**Table 1** Version mapping
Series		Switch Model	Software Version
S5720-SI	S5720-X-SI	S5721-28X-SI-24S-AC	V200R011C10 and later versions

Appearance and Structure

Figure 1 S5721-28X-SI-24S-AC appearance

1	Sixteen 100/1000BASE-X ports Applicable modules: FE optical module GE optical module GE-CWDM optical module GE-CWDM optical module (used only in the OADM scenario and supported in V200R012C00 and later versions) GE-DWDM optical module GE copper module (works at 10 Mbit/s, 100 Mbit/s, or 1000 Mbit/s)	2	Eight combo ports (10/100/1000BASE-T + 100/1000BASE-X) Modules applicable to combo optical ports: FE optical module GE optical module GE-CWDM optical module GE-CWDM optical module (used only in the OADM scenario and supported in V200R012C00 and later versions) GE-DWDM optical module
3	Four 10GE SFP+ ports Applicable modules and cables: GE optical module GE-CWDM optical module GE-DWDM optical module GE copper module 10GE SFP+ optical module (OSXD22N00 not supported) 10GE-CWDM optical module 10GE-DWDM optical module 1 m, 3 m, 5 m, and 10 m SFP+ high-speed copper cables 3 m and 10 m AOC cables 0.5 m and 1.5 m SFP+ dedicated stack copper cables (used for zero-configuration stacking, supported in V200R011C10 and later versions) H87MMA5671A2 GPON optical module (applicable in V200R012C00 and later versions) NOTE: If a port uses a GPON optical module, other 10GE SFP+ optical ports cannot be used.	4	One ETH management port
5	One console port NOTE: It is used with a console cable. The console cable is not delivered with the switch and needs to be separately purchased if needed.	6	One USB port
7	Ground screw NOTE: It is used with a ground cable.	8	Rear card slot NOTE: This slot is reserved for future use.
9	Power module slot 2 NOTE: Applicable power modules: 60 W AC power module 150 W DC power module	10	Power module slot 1 NOTE: Applicable power modules: 60 W AC power module 150 W DC power module

Port Description

100/1000BASE-X port

A 100/1000BASE-X port can send and receive data at 100 Mbit/s or 1000 Mbit/s. Table 2 describes the attributes of a 100/1000BASE-X port.

**Table 2** Attributes of a 100/1000BASE-X port
Attribute	Description
Connector type	LC/PC
Optical interface attributes	Depend on the optical module used
Standards compliance	IEEE802.3z
Working mode	100/1000 Mbit/s auto-sensing

Combo port

A combo port consists of an optical Ethernet port and an electrical Ethernet port on the panel. Each combo port matches only one internal forwarding port. The electrical and optical ports of a combo port are multiplexed, and only one of them can work at a time. When one of the Ethernet ports is working, the other port is shut down.

By default, a combo port works in auto mode, in which the port type is determined as follows:

If the optical port has no optical module installed and the electrical port has no Ethernet cable connected, the port type depends on which port is connected first. If the electrical port is connected by an Ethernet cable first, the electrical port is used for data switching. If the optical port has an optical module installed first, the optical port is used for data switching.
If the electrical port has an Ethernet cable connected and is in Up state, the electrical port is still used for data switching when the optical port has an optical module installed.
If the optical port, no matter in Up or Down state, has an optical module installed, the optical port is still used for data switching when the electrical port has an Ethernet cable connected.
If the optical port has an optical module installed and the electrical port has an Ethernet cable connected, the optical port is used for data switching after the switch restarts.

You can configure a combo port as an electrical or optical port using the combo-port command.

10GE SFP+ port

A 10GE SFP+ Ethernet optical port supports auto-sensing to 1000 Mbit/s. It sends and receives service data at 1000 Mbit/s or 10 Gbit/s. Table 3 describes the attributes of a 10GE SFP+ Ethernet optical port.

**Table 3** Attributes of a 10GE SFP+ port
Attribute	Description
Connector type	LC/PC
Optical port attributes	Depend on the optical module used
Standards compliance	IEEE802.3ae
Working mode	GE/10GE auto-sensing

Console port

The console port is connected to a console for on-site configuration. The port must use a console cable. The console port is used when a switch is powered on for the first time. For details about the attributes of a console port, see Table 4.

**Table 4** Attributes of a console port
Attribute	Description
Connector type	RJ45
Standards compliance	RS-232
Working mode	Duplex Universal Asynchronous Receiver/Transmitter (UART)
Baud rate	9600 bit/s, 19200 bit/s, 38400 bit/s, 57600 bit/s, or 115200 bit/s Default value: 9600 bit/s

ETH management port

You can connect a switch to a configuration terminal or network management workstation through the ETH management port to configure the switch locally or remotely. The port must use an Ethernet cable. You can choose to download the software package through the ETH management port in the BootLoad menu. File transfer through the ETH management port is faster than transfer through the console port. Table 5 describes the attributes of an ETH management port.

**Table 5** Attributes of an ETH management port
Attribute	Description
Connector type	RJ45
Standards compliance	IEEE802.3
Working mode	10/100 Mbit/s auto-sensing
Maximum transmission distance	100 m

In V200R012C00 and later versions, you can log in to the switch that contains the ETH management port for the first time through the ETH port. For details, see "First Login to a Switch" in the Configuration Guide - Basic Configuration. If you have logged in to the device for the first time by pressing and holding the MODE button for 6 seconds or longer and saved the configuration, the default configuration on the ETH port will be cleared. In this case, you cannot log in to the switch for the first time through the ETH port. You are advised to log in to the switch for the first time through the ETH port.

USB port

The USB port can have a USB flash drive connected to upgrade the switch, or transfer configuration files or other files. The USB port can only connect to a USB flash drive that complies with USB 2.0.

USB flash drives from different vendors differ in model compatibility and drivers. If a USB flash drive cannot be used, try to replace it with another one from a mainstream vendor. Switches support a maximum of 128 GB USB flash drives.

Indicator Description

Hold down the mode switch button for 6s and release it to start the web initial login mode. Either of the following situations will occur:

If the switch has no configuration file, the system attempts to enter the web initial login mode. In this mode, the status of mode indicators is as follows:
- If the system enters the web initial login mode successfully, all mode indicators turn green and stay on for a maximum of 10 minutes.
- If the system fails to enter the initial login mode, all mode indicators fast blink for 10 seconds and then restore the default status.
If the switch has a configuration file, the system cannot enter the web initial login mode. In this case, all mode indicators fast blink for 10s, and then return to the default states.

Figure 2 Indicators on the S5721-28X-SI-24S-AC

The S5720-SI series switches provide a command for setting fault indicators, which help field maintenance personnel find a faulty switch quickly.

The SYS indicator and mode indicators (STAT, SPED, and STCK) are used as fault indicators of a switch. If the switch fails, its SYS indicator and mode indicators can be configured to blink red fast so that field maintenance personnel can find this faulty switch.

**Table 6** Description of indicators on the switch
No.	Indicator	Name	Color	Status	Description
1	PWR1	Power module indicator	-	Off	No power module is available in power module slot 1, or the switch has only one power module but the power module does not work normally.
			Green	Steady on	A power module is installed in power module slot 1 and is working normally.
			Yellow	Steady on	The switch has two power modules installed. Any of the following situations occurs in power module slot 1: A power module is available in this slot but its power switch is in the OFF position. A power module is available in this slot but it is not connected to a power source. The power module in this slot has failed.
2	PWR2	Power module indicator	-	Off	No power module is available in power module slot 2, or the switch has only one power module but the power module does not work normally.
			Green	Steady on	A power module is installed in power module slot 2 and is working normally.
			Yellow	Steady on	The switch has two power modules installed. Any of the following situations occurs in power module slot 2: A power module is available in this slot but its power switch is in the OFF position. A power module is available in this slot but it is not connected to a power source. The power module in this slot has failed.
3	SYS	System status indicator	-	Off	The system is not running.
			Green	Fast blinking	The system is starting.
			Green	Slow blinking	The system is running normally.
			Red	Steady on	The system does not work normally after registration, or a fan alarm or temperature alarm has been generated.
4	STAT	Status indicator	-	Off	The status mode is not selected.
4	STAT	Status indicator	Green	Steady on	The status mode (default mode) is selected. If the status mode is selected, the service port indicator shows the port link or activity state.
5	SPED	Speed indicator	-	Off	The speed mode is not selected.
5	SPED	Speed indicator	Green	Steady on	The service port indicators show the port speeds. After 45 seconds, the service port indicators automatically restore to the status mode.
6	STCK	Stack indicator	-	Off	If you are not changing the indicator mode (default): The switch is in stack standby or slave state or the stacking function is not enabled on the switch. If you are changing the indicator mode: The stack mode is not selected.
			Green	Steady on	The switch is a standby or slave switch in a stack, and the service port indicators show the stack ID of the switch.
			Green	Blinking	If you are not changing the indicator mode (default): The switch is a stack master switch or a standalone switch with the stacking function enabled. If you are changing the indicator mode: The switch is the master switch in a stack or a standalone switch, and the service port indicators show the stack ID of the master switch. After 45 seconds, the service port indicators automatically restore to the status mode.
7	MODE	Mode switch button	-	-	When you press this button once, the service port indicators change to the speed mode and show the speed of each service port When you press this button a second time, the service port indicators change to the stack mode and show the stack ID of the local switch. When you press this button a third time, the service port indicators restore to the default mode, and the STAT indicator turns green. If you do not press the MODE button within 45 seconds, the service port indicators restore to the default mode. In this case, the STAT indicator is steady green, the SPED indicator is off, and the STCK indicator is off or blinking green.
8	-	Service port indicator	Meanings of service port indicators vary in different modes. For details, see Table 7 and Table 8.
9	-	ETH port indicator	-	Off	The ETH port is not connected.
			Green	Steady on	The ETH port is connected.
			Green	Blinking	The ETH port is sending or receiving data.
10	-	USB-based deployment indicator	-	Off	No USB flash drive is connected to the switch. The USB port is damaged. The indicator is damaged. The USB flash drive does not have any configuration file and cannot be used for deployment. The switch has been upgraded using the USB flash drive and is restarting.
			Green	Steady on	A USB-based deployment has been completed.
			Green	Blinking	The system is reading data from the USB flash drive.
			Yellow	Steady on	The switch has copied all the required files and completed the file check. The USB flash drive can be removed from the switch.
			Red	Blinking	An error has occurred when the system is executing the configuration file or reading data from the USB flash drive.

**Table 7** Description of service port indicators in different modes (one indicator for each port)
Display Mode	Color	Status	Description
Status	-	Off	The port is not connected or has been shut down.
	Green	Steady on	A link has been established on the port.
	Green	Blinking	The port is sending or receiving data.
Speed	-	Off	The port is not connected or has been shut down.
	Green	Steady on	10M/100M/1000M port: The port is operating at 10/100 Mbit/s. 1000M/10GE port: The port is operating at 1000 Mbit/s.
	Green	Blinking	10M/100M/1000M port: The port is operating at 1000 Mbit/s. 1000M/10GE port: The port is operating at 10 Gbit/s.
Stack	-	Off	Port indicators do not show the stack ID of the switch.
	Green	Steady on	The switch is not the master switch in a stack. If the indicator of a port is steady on, the number of this port is the stack ID of the switch. If the indicators of ports 1 to 9 are steady on, the stack ID of the switch is 0.
	Green	Blinking	The switch is the master switch in a stack. If the indicator of a port is blinking, the number of this port is the stack ID of the switch. If the indicators of ports 1 to 9 are blinking, the stack ID of the switch is 0.

**Table 8** Description of service port indicators in different modes (two indicators for each port)
Display Mode	Color	Status	Description
Status	-	Off	The port is not connected or has been shut down.
	Green	Steady on	A link has been established on the port.
	Yellow	Blinking	The port is sending or receiving data.
Speed	-	Off	The port is not connected or has been shut down.
	Green and yellow	Steady on	10M/100M/1000M port: The port is operating at 10/100 Mbit/s. 1000M/10GE port: The port is operating at 1000 Mbit/s.
	Green and yellow	Blinking	10M/100M/1000M port: The port is operating at 1000 Mbit/s. 1000M/10GE port: The port is operating at 10 Gbit/s.
Stack	-	Off	Port indicators do not show the stack ID of the switch.
	Green and yellow	Steady on	The switch is not the master switch in a stack. If the indicator of a port is steady on, the number of this port is the stack ID of the switch. If the indicators of ports 1 to 9 are steady on, the stack ID of the switch is 0.
	Green and yellow	Blinking	The switch is the master switch in a stack. If the indicator of a port is blinking, the number of this port is the stack ID of the switch. If the indicators of ports 1 to 9 are blinking, the stack ID of the switch is 0.

Power Supply Configuration

The S5721-28X-SI-24S-AC uses pluggable power modules. It can be configured with a single power module or double power modules for 1+1 power redundancy. Pluggable AC and DC power modules can be used together in the same switch.

If a 60 W AC power module and a 150 W DC power module is used in the same switch, the maximum output power of the 150 W DC power module is 60 W.

Figure 3 shows the power supply connections of dual DC power modules. After DC power is transmitted to the PWR module, the PWR module provides 12 V output voltage, and the motherboard provides power for the entire device.

Figure 3 Power supply connections of dual DC power modules

NEG: negative wire

RTN: positive wire

GND: 12 V reference ground

Figure 4 shows the power supply connections of dual AC power modules. After AC power is transmitted to the PWR module, the PWR module provides 12 V output voltage, and the motherboard provides power for the entire device.

Figure 4 Power supply connections of dual AC power modules

L: Live wire

N: Neutral wire

PGND: Protection ground wire

GND: 12 V reference ground

Heat Dissipation

The S5721-28X-SI-24S-AC has one built-in fan for forced air cooling. Air flows in from the left side and front panel, and exhausts from the right side.

This figure only shows the airflow direction and does not depict the actual device.

Technical Specifications

Table 9 lists technical specifications of the S5721-28X-SI-24S-AC.

**Table 9** Technical specifications
Item	Description
Memory (RAM)	512 MB
Flash	512 MB in total. To view the available flash memory size, run the display version command.
Mean time between failures (MTBF)	36 years
Mean time to repair (MTTR)	2 hours
Availability	> 0.99999
Service port surge protection	Common mode: ±7 kV
Power supply surge protection	Using AC power modules: ±6 kV in differential mode, ±6 kV in common mode Using DC power modules: ±1 kV in differential mode, ±2 kV in common mode
Dimensions (H x W x D)	44.4 mm x 442.0 mm x 420.0 mm (1.75 in. x 17.4 in. x 16.5 in.)
Weight (including package)	8.6 kg (18.96 lb)
Stack ports	GE optical ports and 10GE SFP+ optical ports except combo ports on the front panel
RTC	Supported
RPS	Not supported
PoE	Not supported
Rated voltage range	100 V AC to 240 V AC, 50/60 Hz -48 V DC to -60 V DC
Maximum voltage range	90 V AC to 264 V AC, 47 Hz to 63 Hz -36 V DC to -72 V DC
Maximum power consumption (100% throughput, full speed of fans)	41 W
Typical power consumption (30% of traffic load) Tested according to ATIS standard EEE enabled No PoE power consumption	34.5 W
Operating temperature	0°C to 45°C (32°F to 113°F) at an altitude of 0-1800 m (0-5906 ft.) NOTE: When the altitude is 1800-5000 m (5906-16404 ft.), the highest operating temperature reduces by 1°C (1.8°F) every time the altitude increases by 220 m (722 ft.).
Short-term operating temperature	-5°C to +50°C (23°F to 122°F) at an altitude of 0-1800 m (0-5906 ft.) NOTE: When the altitude is 1800-5000 m (5906-16404 ft.), the highest operating temperature reduces by 1°C (1.8°F) every time the altitude increases by 220 m (722 ft.). The equipment can operate beyond the normal operating temperature range for a short-term period, but the following conditions must be met: The equipment operates at a temperature of over 45°C (113°F) consecutively for at most 96 hours in one year. The equipment operates at a temperature of over 45°C (113°F) for a total of no more than 360 hours in one year. The equipment operates at a temperature of over 45°C (113°F) for no more in 15 times in one year. The equipment may be damaged or experience unexpected exceptions if any of the preceding limits is exceeded. The equipment cannot start when the temperature is lower than 0°C (32°F). The maximum distance of optical modules used in these conditions cannot exceed 10 km.
Storage temperature	-40°C to +70°C (-40°F to +158°F)
Noise under normal temperature (27°C, sound power)	< 50.3 dB(A)
Relative humidity	5% to 95%, noncondensing
Operating altitude	AC power modules configured: 0-5000 m (0-16404 ft.) DC power modules configured: 0-2000 m (0-6562 ft.)
Certification	EMC certification Safety certification Manufacturing certification
Part number	98010661