Dell PowerConnect J-8208, Hardware Manual

Page: 98 / 276

To calculate the number of power supplies required for your switch configuration:
1.
Determine the power requirement of the chassis—with the fan tray, SRE modules,
and SF module, but no line cards—by consulting Table 38 on page 82.
The watt values shown in Table 38 on page 82 are the amount of power reserved by
power management for the chassis in its power budget. It uses these values when
calculating used and available power and when determining whether sufficient power
exists to meet N, N+1, or N+N requirements.
When power management is configured for N+N power redundancy, it reserves less
power for the chassis so that more power is available for line cards.
Table 38: Power Reserved for the Chassis
Junos OS Release 10.2 or Later
1600 W N+1 Configuration
1200 W N+N Configuration
NOTE: The amount of power that power management reserves for the
chassis is a set value that does not vary depending on chassis components
installed.
2.
To the power reserved for the chassis, add the power requirements of the line cards.
For line card power requirements, refer to “Power Requirements for J-EX8208 Switch
Components” on page 76.
For example, for a switch fully loaded with 8-port SFP+ line cards and using N+1 power
redundancy, the total power requirement:
= reserved chassis power + 8 (8–port SFP + line cards)
= 1600 W + 8 (450) W
= 1600 W + 3600 W
= 5200 W
For a switch fully loaded with 8-port SFP+ line cards, using N+N power redundancy,
and running Junos OS Release 10.2, the total power requirement:
= reserved chassis power + 8 (8–port SFP + line cards)
= 1200 W + 8 (450) W
= 1200 W + 3600 W
= 4800 W
3.
Calculate the number of power supplies (N) required to meet the total power
requirement by dividing the total power requirement by the output wattage of one
power supply and then rounding up.
82
Dell PowerConnect J-Series J-EX8208 Ethernet Switch Hardware Guide