Cisco Nexus 2000 Series Quick reference guide

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White Paper
Airflow Sleeve and Airflow Vent
Cisco Nexus 2000 and 3000 series
What%You%Will%Learn%............................................................................................................%1!
Data%Centre%Physical%Deployments%Nexus%2000/3000%series%................................................%2!
Data%Centre%Physical%Temperature%Optimizations%Nexus%2000/3000%series%..........................%3!
Installation%of%the%Airflow%Sleeve%.........................................................................................%5!
Installation%of%the%Airflow%Vent%...........................................................................................%5!
Example%of%Airflow%optimization%.........................................................................................%6!
Conclusion%...........................................................................................................................%7!
For%More%Information%..........................................................................................................%7!
What You Will Learn
The purpose of this note is to explain two airflow optimization solutions for the Cisco Nexus 2000 and 3000 series.
In situations where the Nexus 2000 and 3000 Series ports are aligned with server ports, proper air sealing at the
front of the chassis may be required to achieve optimal airflow.
This document provides an explanation for the airflow sleeve and airflow vent optimization solutions.

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Data Centre Physical Deployments Nexus 2000/3000 series
Optimizing airflow for standard front to back airflow deployments (power side intake)
In Data Centre Deployments, the Cisco Nexus 2000 Fabric Extender (FEX) is typically installed on top of rack. As
it’s designed for Data Centre deployments, the ports are on the rear panel of its chassis, facing the server ports.
Dues to it’s shorter depth than a standard rack: 19.7 inch (XX centimeters), it can be mounted in two scenarios:
either aligned in the front (figure 1.) or aligned in the back of the rack (figure 2.)
Figure 1. Front of Rack Aligned Figure 2. Back of Rack Aligned
Figure 3. Front of Rack Aligned Airflow Figure 4. Back of Rack Aligned Airflow
The scenario described in Figure 2 is majorly deployed, as it’s the most convenient mount to connect the server
ports to the FEX as they are aligned the ports can be most easily connected. Due to the shorter depth of the FEX,
in certain higher temperature Data Centers, the cold air may not be sufficient and the FEX can reach it’s
temperature thresholds faster. From a cooling prospective, it is also best practices to seal the FEX to fit the rack for

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better airflow optimizations. The Back of Rack Aligned deployment airflow can be optimized so the FEX
temperature at intake can decrease; this is achieved with an Airflow Sleeve.
Optimizing airflow for reversed, back to front airflow deployments (port side intake)
When a FEX is installed at the top of rack without a device that assures proper sealing on top (shelf, switch,
server..) the Inlet Air could be of higher temperature than cold aisle. The Airflow Vent deployment helps directing
the airflow and reducing the temperature inside the FEX by maximizing the cold airflow at intake as shown on
above Figure 5.
Figure 5. Back to Front Airflow
Data Centre Physical Temperature Optimizations Nexus 2000/3000 series
Two optimizations are offered:
1) Optimization for standard airflow (front-to-back, power supply side intake) with the Airflow Sleeve (NXA-
AIRFLOW-SLV)
2) Optimization for reversed airflow (back-to-front, port side intake) with the Airflow Vent (NXA-ACC-KIT-
BAV=)

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Figure 6. The Airflow Sleeve Figure 7. Airflow Optimization with the Airflow Sleeve
In Data Center deployments, where the Nexus 2000 / 3000 temperature is close or reached the temperature
threshold, the Airflow Sleeve will help reduce the temperature at intake and avoid potential shutdown of the device
if the second temperature threshold is reached.
When deployed with reversible airflow (back-to-front, port side intake) and stacked on top of multiple devices, the
cold air enters via the port side of the switch/FEX. The FEX design is with an incurved exhaust on the top of the
chassis that facilitates the hot air evacuation and direction. While this is a design optimized for front-to-back airflow,
it is less optimized for a reversible back-to-front airflow when the Nexus 3000 or Nexus 2000 is the unit that resides
at the very top of the rack (first unit). The Airflow Vent (Figure 8) will help direct the cold airflow inside the chassis.
The Airflow Vent can be very easily placed on top of the exhaust and direct the cold air appropriately in the Nexus
3000 / Nexus 2000 FEX.
Figure 8. Airflow Optimization with Airflow Vent

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Installation of the Airflow Sleeve
The airflow sleeve consists of an adjustable length 1-RU sleeve. It can be attached to the Rack in the front side of
the chassis as shown on Figure 9. The sleeve creates a channel for the cold air outside the rack to enter the
chassis more efficiently. The two power cables connecting to the power supplies should be plugged through the
sleeve, one after the other. The airflow sleeve provides an adjustable depth for the FEX, between 26 and 30
inches. The part number for the Airflow Sleeve is NXA-AIRFLOW-SLV.
Figure 9. Airflow Sleeve Installation
Note: After installation of the Airflow Sleeve, the power supplies and fan tray are not serviceable without removal of
the sleeve. Removing the sleeve can be done in-rack.
The Figure below is a picture of a Nexus 2200 platform extended with the Nexus Airflow Sleeve.
Installation of the Airflow Vent
The airflow vent consists of a metallic cover to place on the upper exhaust of the FEX as shown on Figure 10. The
vent creates a channel for the cold air to enter the FEX from the server facing ports, when the FEX is utilized with a
back-to-front airflow and placed in top of rack. The cold air can enter the FEX chassis more efficiently. The part
number for the Airflow Vent kit is NXA-ACC-KIT-BAV and contains an accessory kit (mounting rails with snap on

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holes for airflow vent) with the air vent. It may be utilized in conjunction with the Airflow Sleeve to seal better the
airflow hot exhaust.
Figure 10. Airflow Vent Installation
Example of Airflow optimization
This is an example showing the optimizations with the Airflow Sleeve.
In a Data Center where the FEX is back of rack aligned, using standard front-to-back airflow (power supply side
intake), the temperature at the intake is at 35 degrees as shown on Figure 11. After installation of the Airflow
Sleeve, the temperature decreased by 7 degrees Celsius as shown on Figure 12. It is to note, that this is an
example of temperature reduction due to the Airflow Sleeve. The temperature delta may vary based on
environments, for example the decrease can reach higher values for warmer environments.
Figure 11. Nexus 2000 Temperature without the Airflow Sleeve (as shown on Figure 4)
Figure 12. Nexus 2000 Temperature with the Airflow Sleeve (as shown on Figure 6)

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Conclusion
The airflow sleeve provides a solution to airflow sealing in the Data Centre.
Also, when the temperature threshold for the FEX are close or crossed due to warmer data center deployment, the
airflow sleeve and the airflow vent provide a solution to reduce the temperature at the intakes respectively in either
front-to-back or back-to-front airflows.
For More Information
http://www.cisco.com/go/nexus2000
Printed in USA C11-670244-00 05/11