# How many license files are required for a stack of CE switches

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You can apply for a license file for each ESN or one license file for multiple ESNs.

###### Other related questions:
Load a license file to a stack of switches

How do I calculate the number of power modules required on a CE switch
Description
How do I calculate the number of power modules required on a CE switch?
Solution
Calculate the total power consumption of all working modules on the switch and divide this value with the maximum power that a power module can provide. Add 1 to the integer part of the calculation result. The sum N is minimum number of power modules required for the switch. In real-world applications, more than N power modules are configured to implement power redundancy. The power modules can work in N+1 or N+N backup mode.
For example, a CE12808 chassis uses 2700 W AC power modules and is configured with two 48*10GE interface cards, five CE-SFU08A cards, and two MPUs.
With this configuration, the maximum power consumption of the chassis is 2455 W. 2455 W divided by 2700 W is smaller than 1, so the integer part is 0. That is, a minimum of one power module is required (0 + 1 = 1). Considering power redundancy, the number of power modules used on the chassis is:
In N+1 backup mode: N + 1 = 1 + 1 = 2
In N+N backup mode: N + N = 1 + 1 = 2
For details, visit http://support.huawei.com/onlinetoolsweb/network_configtool/index.jsp?lang=en&audience=enterprise

For CE switches, should a license file be loaded before or after a stack is set up
You can load license files for switches before or after setting up a stack. The result is not affected by the operation sequence.

How many cables are required for setting up a stack of CE switches
At least one cable is required to connect two member switches. To ensure reliability, you are advised to use two cables to connect different cards of two member switches.

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