Get Perfmon Counter Packets Received Discarded On Multiple Servers

.SYNOPSIS Purpose of this script is to report on a particular performance monitor counter --> "Packets Received Discarded" on multiple servers.

Please review this blog post for the background, and further discussion.

.DESCRIPTION Script was initially created to analyse the Packets Received Discarded on multiple Exchange servers. This is due to experiencing multiple performance issues and one KPI of the underlying issue was the number of discarded packets.

The script will get a collection of NICs from the specified server, and then loop through them and remove the non-physical ones. For example do not want to see Teredo, ISATAP or 6to4 interfaces. For the purposes of this script we are concerned with the physical ones, and that includes the "physical" NICs that are made visible in virtual guest Operating Systems.

NIC names are not hardcoded into the script else it would not be portable across physical server types and hypervisors.

Packets Received Discarded is the performance counter reported to Windows by the NIC which states how many packets were sucessfully received, i.e. not corrupt or failed checksum that were discarded before the NIC could push them up the stack. This has been documented as a known issue with certain hypervisors when the virtual NIC buffer is not set high enough or there are other issues on the hypervisor host such as a configuration or performance issue.

Script will report to the screen the number of discarded packets. If required you can modify to output to a CSV using standard methods.

Version 4 of this script was modified to output to a CSV using standard methods.
In the CSV file there will be one line per selected interface on each server queried. Thus if a server has two physical NICs then there will be two lines for that particular server. See note above stating that logical interfaces will be filtered out.

.ASSUMPTIONS Script is being executed with sufficient permissions to retrieve perfmon counters on the server(s) targeted.

You can live with the Write-Host cmdlets :)

You can add your error handling if you need it.

.VERSION 2.0 2-7-2014 -- Initial version

3.0 22-10-2014 -- Added additional output so that the server uptime is also displayed. This is useful to compare numbers, as servers may have been restarted at different times. Also added OS install date at customer request, so that build time discrepencies can be noted.

4.0 14-2-2015 -- Added custom PSObject to hold output. This allows for easy manipulation and feeding it to Export-CSV See this post for details on the subject https://gallery.technet.microsoft.com/PowerShell-Template-af07b5a3

                    Fixed a couple of spelling typos.
                    Added example in for Get-ADComputr cmdlet.
                    Added in Export to CSV
                    Changed the install date to be short DateTime.  Do not care at what exact time of day server was installed just the date. 

.Author Rhoderick Milne https://blog.rmilne.ca

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