Complete Hardware Guide for EX8208 Ethernet Switches
To calculate the number of power supplies required for your switch configuration:
1.Determine the power requirement of the base chassis (that is, the combined power requirements of the fan tray, SRE module or modules, and the SF module) by consulting Table 50 on page 118.
The watt values shown in Table 50 on page 118 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.
Starting with Junos OS Release 10.2, 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 50: Power Reserved for the Chassis
| Junos OS Release 10.1 or | Junos OS Release 10.2 or |
| Earlier | Later |
N+1 Configuration | 1600 W | 1600 W |
N+N Configuration | 1600 W | 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. The reserved power is the same for base and redundant configurations and for switches that do not have all base 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 EX8208 Switch Components” on page 111.
For example, for a switch fully loaded with
=reserved chassis power + 8
=1600 W + 8 (450) W
=1600 W + 3600 W
=5200 W
For a switch fully loaded with
=reserved chassis power + 8
=1200 W + 8 (450) W
=1200 W + 3600 W
=4800 W
118 | Copyright © 2010, Juniper Networks, Inc. |
