Alias – Simple yet powerful

Alias – Simple yet powerful About: Alias mySimpleAlias <a maybe complicated command you would never remember> Alias commands can be composed of multiple lines and embed variables. Below is an example of alias used as configuration template for automating configuration with just few arguments. Sunch template can satisfy complex configurations and be highly reusable. This high-level scripting or command bundling is simple to implement yet powerful. The below example is a multi-line alias with variables (%<x>) alias set-baremetal !! Syntax : set-baremetal <INTF> <Po ID> <DESCR> <VLAN> !! Example: set-baremetal e1,2 po1 “To Server 42” 200 10 config 20 interface...
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Arista 7280QR-C36 Load Balancing Optimization for Dual Homed Systems and Networks

Arista 7280QR-C36  The Arista DCS-7280QR-C36 switch is a purpose built flexible fixed configuration 1RU system capable of supporting a wide range of interface choices. Its designed for the highest performance environments such as IP Storage, Content Delivery Networks, Data Center Interconnect and IP Peering. The 7280QR-C36 is optimized for environments with dual connected nodes such as storage and for spine applications with dual homed leaf switches. This technical application note describes the internal optimized load-balancing mechanism used within the switch and how network architects can best deploy this system to maximize overall system performance. The internal architecture of the DCS-7280QR-C36...
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Troubleshooting congestion – Investigating and taking corrective steps

  1) Introduction Congestion might not be obvious, it can be discovered reactively in disastrous situations, or proactively by collecting statistics off equipment and investigating symptoms demonstrated by the applications and systems.   Deep buffers on switches is a blanket and effortless solution to the problem, but it might not be materially possible or justifiable everywhere on a network. This document discusses design considerations in case of congestion.     2) Measuring The first step (which might seem obvious) for understanding some potential issues is to translate the symptoms such as slow, unresponsive, poor performance, into measurable and baselined metrics...
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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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Introduction to Managing EOS Devices

Summary   Several mechanisms exist to manage and instrument Arista Networks’ devices, ranging from industry standard SNMP counters to more Arista EOS/platform-centric functionality and deep debugging capabilities. The following articles introduce some fundamental management activities:   Setting up Management Monitoring Troubleshooting Platform Specific Monitoring and Troubleshooting Automation and Extensibility Annex A – Configuration Example Annex B – EOS Tips for Power Users   This document serves to highlight the basic parameters required to automate monitoring of an Arista EOS based device, while providing a high level overview of additional, more advanced functionality for low level troubleshooting and application specific monitoring. Many of the topics...
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Troubleshooting High CPU Utilization

Introduction   This article aims at helping you define what is CPU load on an Arista switch, how to know when it has a high load, and help troubleshoot high CPU utilization. We will cover different topics related to High CPU utilization: How do I identify if my switch has a high CPU? What is considered normal CPU % utilization? What is example of a High CPU utilization? How to identify average load on an Arista switch? What is the difference between CPU load average and CPU utilization How to interpret the load numbers? Can the load average be greater than...
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Using tcpdump for troubleshooting

tcpdump is a command line packet sniffer (built into Linux) that is used to assist in troubleshooting network problems. Any traffic coming to or from the control plane of the Arista is visible when running the tcpdump utility on the Arista.  This does not include data plane traffic transiting the Arista – for capturing this type of traffic, Arista Aristaes support Monitor / SPAN ports which can be used to copy traffic to a sniffer or to other suitable capture device for analysis. tcpdump allows users to instantly analyse important traffic such as Spanning Tree and routing protocols, as well...
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Debugging EOS agents

EOS’s architecture is built around the notion of agents. While the CLI show commands offer some great insights into the operational status of the switch, there is deeper level of detail that can be gathered from the agents by using a EOS debugging feature called agent tracing. Through this feature, which delivers live debug output to the CLI, EOS provides extensive troubleshooting information and enables users to debug complex control plane or protocol layer interactions. To configure agent tracing, first check the list of available agents. For example, in order to see the list of all agent starting with ‘A’, use: Arista#show trace...
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How to store and view previous contents of ‘show tech-support’

Introduction Starting with EOS 4.8.1, Arista introduced a unique feature called CLI Scheduler. Besides helping with troubleshooting and debugging Arista switches, this feature is used in order to automatically save the last 100 outputs of show tech-support (taken every hour). Please see an Arista EOS Manual for further details on the CLI Scheduler. Scheduling a show tech-support command The schedule command facilitates the periodic execution of a specified CLI command. Command parameters can be used in order to configure: the interval between consecutive executions of the command the maximum number of log files to be saved Starting with 4.8.1, by default, the...
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