Friday, March 30, 2018

Cisco Nexus 7000 and Nexus 7700 Series Power Supply Options

The Nexus 7000 and Nexus 7700 use power supplies with +90% power supply efficiency, reducing power wasted as heat and reducing associated data center cooling requirements. The switches offer different types of redundancy modes. They offer visibility into the actual power consumption of the total system, as well as modules enabling accurate power consumption monitoring, for the right sizing of power supplies, UPSs, and environmental cooling. Variable-speed fans adjust dynamically to lower power consumption and optimize system cooling for true load.
  • Power redundancy: Multiple system-level options for maximum data center availability.
  • Fully hot-swappable: Continuous system operations; no downtime in replacing power supplies.
  • Internal fault monitoring: Detects component defect and shuts down unit.
  • Temperature measurement: Prevents damage due to overheating (every ASIC on the board has a temperature sensor).
  • Real-time power draw: Shows real-time power consumption.
  • Variable fan speed: Automatically adjusts to changing thermal characteristics; lower fan speeds use lower power.
Cisco Nexus 7000 and Nexus 7700 Series 3.0kW AC Power Supply Module
The 3.0kW AC power supply shown in Figure 1-30 is designed only for the Nexus 7004 chassis and is used across all the Nexus 7700 Series chassis. It is a single 20-ampere (A) AC input power supply. When connecting to high line nominal voltage (220 VAC) it will produce a power output of 3000W; connecting to low line nominal voltage (110 VAC) will produce a power output of 1400W.
Figure 1-30 Cisco Nexus 7000 3.0kW AC Power Supply

NOTE: Although the Nexus 7700 chassis and the Nexus 7004 use a common power supply architecture, different PIDs are used on each platform. Therefore, if you interchange the power supplies, the system will log an error complaining about the wrong power supply in the system; although technically this might work, it is not officially supported by Cisco.
Cisco Nexus 7000 and Nexus 7700 Series 3.0kW DC Power Supply Module
The 3.0kW DC power supply shown in Figure 1-31 is designed only for the Nexus 7004 chassis and is used across all the Nexus 7700 Series chassis. The Nexus 3.0kW DC power supply has two isolated input stages, each delivering up to 1500W of output power. Each stage uses a –48V DC connection. The unit will deliver 1551W when only one input is active and 3051W when two inputs are active.
Figure 1-31 Cisco Nexus 7000 3.0kW DC Power Supply

Cisco Nexus 7000 Series 6.0kW and 7.5kW AC Power Supply Modules
The 6.0kW and 7.5kW power supplies shown in Figure 1-32 are common across Nexus 7009, 7010, and 7018. They allow mixed-mode AC and DC operation, enabling migration without disruption and providing support for dual environments with unreliable AC power, with battery backup capability.
Figure 1-32 Cisco Nexus 7000 6.0kW and 7.5kW Power Supplies

Table 1-10 shows the specifications of both power supplies with different numbers of inputs and input types.
Table 1-10 Nexus 7000 and Nexus 7700 6.0kW and 7.5kW Power Supply Specifications
Power Supply Type
Number of Inputs
Input Power
Single input
Dual input
Dual input
110 and 220V
Single input
Dual input
Cisco Nexus 7000 Series 6.0kW DC Power Supply Module
The 6kW DC power supply shown in Figure 1-33 is common to the 7009, 7010, and 7018 systems. The 6kW has four isolated input stages, each delivering up to 1500W of power (6000W total on full load) with peak efficiency of 91% (high for a DC power supply). The power supply can be used in combination with AC units or as an all DC setup. It supports the same operational characteristics as the AC units:
  • Redundancy modes (N+1 and N+N)
  • Real-time power—actual power levels
  • Single input mode (3000W)
  • Online insertion and removal
  • Integrated lock and On/Off switch (for easy removal)
Figure 1-33 Cisco Nexus 7000 6.0kW DC Power Supply

Multiple power redundancy modes can be configured by the user:
  • Combined mode, where the total power available is the sum of the outputs of all the power supplies installed. (This is not redundant.)
  • PSU redundancy, where the total power available is the sum of all power supplies minus one, otherwise commonly called N+1 redundancy.
  • Grid redundancy, where the total power available is the sum of the power from only one input on each PSU. Each PSU has two supply inputs, allowing them to be connected to separate isolated A/C supplies. In the event of an A/C supply failure, 50% of power is secure.
  • Full redundancy, which is the combination of PSU redundancy and grid redundancy. You can lose one power supply or one grid; in most cases this will be the same as grid redundancy.
Full redundancy provides the highest level of redundancy, so it is recommended. However, it is always better to choose the mode of power supply operation based on the requirements and needs.
An example of each mode is shown in Figure 1-34.
Figure 1-34 Nexus 6.0kW Power Redundancy Modes

To help with planning for the power requirements, Cisco has made a power calculator that can be used as a starting point. It is worth mentioning that the power calculator cannot be taken as a final power recommendation.
The power calculator can be found at

More Related

Tuesday, March 13, 2018

FEC/Forward Error Correction Enables 40km Reach QSFP28 100Gb Pluggable Optical Transceivers

FEC (Forward Error Correction) is used in many forms of data communication. You’ll find it in wireless networks, space communication, undersea fiber optic networks, bar code scanners, and your CD player (if you still have one).

In this article it shows that FEC enables longer reach in a new pluggable optical transceiver. (QSFP100 “ER4-Lite”, it is a new addition to the Cisco “QSFP100” product family, as it’s in a QSFP28 form factor, and is great for data center interconnects up to 40km reach without optical amplification.)

You might also be wondering why we need a “Lite” version, when we already have a 40km IEEE standardized “100GBASE-ER4” transceiver. It turns out the laser power and receiver sensitivity required by the IEEE standard make it more expensive and requires the larger CFP form factor. In contrast, QSFP100 ER4-Lite uses components with relaxed specifications and consumes less power, so it can fit in a QSFP28 form factor. This is a much better size for high density data center applications. And it can still support 40km reach as long as the host platforms at both ends encode and decode FEC.

FEC on host platforms is not that new. It’s actually required by IEEE 100GBASE-SR4 and other non-IEEE optical interface standards such as the CWDM4 MSA and the PSM4 MSA. So all Cisco switches and routers with QSFP28 ports have it.

For those who need to link to other systems already in place, the QSFP100 ER4-Lite interoperates with CPAK ER4-Lite, IEEE 100GBASE-ER4, and IEEE 100GBASE-LR4 at reaches identified in the figure below. 

These don’t use FEC, so make sure to have it turned off at both ends.
More information on Cisco’s QSFP100 ER4-Lite transceiver module is available on the QSFP100 product family data sheet.

More Related