Dell PowerConnect J-8208 Hardware Guide - Page 98

Dell PowerConnect J-Series J-EX8208 Ethernet Switch Hardware Guide 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 N+1 Configuration 1600 W N+N Configuration 1200 W 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