Reversing The Airflow of a Running Switch

Occasionally customers have a switch in production that they need to change the airflow direction of e.g. from a front-to-rear (-F) to a rear-to-front (-R), or vice-versa, without shutting down the switch. The following procedure outlines the steps to follow in order to accomplish this. This procedure assumes that you already have the replacement fans and PSUs on hand and are ready to perform the swap. Start with the switch powered up, both power supplies powered and providing power to the switch. Gain access to the switch’s serial console to check status and run CLI commands as need be. Add...
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Changing the switchport default mode

By default all ports on an Arista switch are configured to be switch ports, as you would expect. If you are mostly dealing with routed ports, this behaviour may not be totally desirable. Starting in EOS-4.18.0, this behaviour is configurable e.g. we can have all interfaces in routed mode by default. switch1...11:10:56(config)#show run int et 1-4interface Ethernet1interface Ethernet2interface Ethernet3interface Ethernet4switch1...11:11:00(config)#show interface Et1-4 switchport | i Name|Switchport:Name: Et1Switchport: EnabledName: Et2Switchport: EnabledName: Et3Switchport: EnabledName: Et4Switchport: Enabled To change the default, simply issue the configuration command switchport default mode routed As you can see, all interfaces are now in routed mode by default:...
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Understanding EOS Software Download Options

This post is to help explain the different Software Download options for a particular EOS release. For recommendations on which train or version of EOS you should use, please take a look at our Software Lifecycle, and Recommended Release pages. This advice only concerns images located in the Active and Support Only Releases folder. Images from the Other Releases and EFT folders are not for general use. Those releases are available only for specific deployments, and should only be used when specifically recommended by Arista. In this case, I’m taking a look at EOS-4.17.1F and you can see from the...
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Introduction to Managing EOS Devices – Memory Utilisation

A common question that users new to EOS have is concerning the high levels of memory utilisation seen on Arista switches (~70% utilised). Typically this is first flagged by the NMS and triggers a low memory warning or alarm. Unlike a traditional switching OS, EOS uses Linux page caching. Most free memory is used as a live cache and very low ‘free memory’  numbers are entirely normal, providing that enough memory is available from the buffers and cached memory for applications demanding more RAM. In this case, the OS is capable of freeing up memory from cache as processes demand it. Memory...
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