find all equipment vendors on the network using MAC and macvendors web request

After looking at other sites I got some other clues, and all of a sudden I had a breakthrough, and was able to write it myself! With understanding! (Updating the target 2012R2 server to PS V7 didn't hurt either!)

It's not perfect, but any more work is the law of diminishing returns. It does what I want:
it gets me all the vendor names of all network neighbor devices with the IP address.

I initially wanted to start with the first 6 characters of the mac address, but found Windows 10 displaying dashes and 2012R2 not, so I had to manipulate the output depending. My original intention was to only show unique vendor codes but now I am glad I have all the IP's for each unique device instead of just unique vendors.

To make it faster (and also to try to not lean on macvendors too much) I skipped all the duplicates and only looked up each unique sextet. I don't know what macvendors' threshold is but a second between lookups works fine. No match on the vendor lookup throws a huge messy error so I had to account for that.

I had a lot more spaces and line feeds but took them all out. It affects the readability a little but I developed some rules for myself along the way. I'm sure there is a better way to do it, I have seen a lot of really amazing and dense PS out there but I wanted to maintain a COBOL-like readability. (Yes, I have written production COBOL which makes me a dinosaur.) :^)

# get-vendor-name - use first 6 of mac to poll macvendors for name
$ErrorActionPreference = 'SilentlyContinue' #if no name match is found
$netNeighbors = Get-NetNeighbor -AddressFamily IPv4 `
    | where {$_.State -ne 'Unreachable' -and $_.State -ne 'Permanent'} `
    | sort LinkLayerAddress -Unique
ForEach ($neighbor in $netNeighbors)
    {$IP = ($neighbor.IPAddress).PadRight(16)
     $mac = $neighbor.LinkLayerAddress
     if ($mac.Length -eq 17) #if mac has delimeters
        {$oui = $mac.Substring(0,8)} else {$oui = $mac.Substring(0,6)}
     if ($oui -ne $oldOui)   #if unique vendor code
        {$vendor = (Invoke-WebRequest -Uri "https://api.macvendors.com/$oui").Content
        Start-Sleep -Milliseconds 1000 }    #don't get blocked by macvendors
     else {$vendor = '.'}    #else do not look up duplicates - show '.'
     Write-Host $oui, $ip, $vendor
     $oldOui = $oui
     $vendor = '' }

000000 192.168.123.136  XEROX CORPORATION
000074 192.168.123.103  RICOH COMPANY LTD.
000e58 192.168.123.96   Sonos, Inc.
000e58 192.168.123.75   .
000e58 192.168.123.85   .
001d50 192.168.123.65   SPINETIX SA
0090a9 192.168.123.47   WESTERN DIGITAL
01005e 224.0.0.2
01005e 224.0.0.22       .
01005e 224.0.0.251      .
01005e 224.0.0.252      .
01005e 239.254.127.63   .
01005e 239.255.255.250  .
0e1b2f 192.168.123.28
18b169 192.168.123.5    Sonicwall
1e83e4 192.168.123.30
204747 192.168.123.3    Dell Inc.
204747 192.168.123.56   .
24a43c 192.168.123.64   Ubiquiti Networks Inc.
24be05 192.168.123.19   Hewlett Packard
3024a9 192.168.123.240  HP Inc.
347e5c 192.168.123.52   Sonos, Inc.
40b034 192.168.123.84   Hewlett Packard
48a6b8 192.168.123.87   Sonos, Inc.
48a6b8 192.168.123.97   .
48a6b8 192.168.123.91   .
48a6b8 192.168.123.72   .
48a6b8 192.168.123.62   .
48a6b8 192.168.123.135  .
4c3fd3 192.168.123.57   Texas Instruments
542a1b 192.168.123.51   Sonos, Inc.
686dbc 192.168.123.200  Hangzhou Hikvision Digital Technology Co.,Ltd.
6c2b59 192.168.123.122  Dell Inc.
6c2b59 192.168.123.105  .
6c4b90 192.168.123.43   LiteON
6c4b90 192.168.123.41   .
7483c2 192.168.123.81   Ubiquiti Networks Inc.
74e6e2 192.168.123.76   Dell Inc.
7828ca 192.168.123.74   Sonos, Inc.
84fdd1 192.168.123.106  Intel Corporate
86f907 192.168.123.42
8c3bad 192.168.123.80   NETGEAR
9c934e 192.168.123.10   Xerox Corporation
9c934e 192.168.123.100  .
a02195 192.168.123.55   Samsung Electronics Co.,Ltd
a02195 192.168.123.73   .
a0510b 192.168.123.60   Intel Corporate
a41f72 192.168.123.71   Dell Inc.
a4bb6d 192.168.123.88   Dell Inc.
a6b6af 192.168.123.31
ac8112 192.168.123.69   Gemtek Technology Co., Ltd.
ac8112 192.168.123.111  .
ac8112 192.168.123.89   .
ac8112 192.168.123.99   .
b083fe 192.168.123.1    Dell Inc.
b2112b 192.168.123.27
b88a60 192.168.123.70   Intel Corporate
b8ca3a 192.168.123.48   Dell Inc.
bc305b 192.168.123.40   Dell Inc.
c272e9 192.168.123.32
c64dd4 192.168.123.33
cecf52 192.168.123.36
d49524 192.168.123.22   Clover Network, Inc.
d49524 192.168.123.21   .
d49524 192.168.123.49   .
d49524 192.168.123.94   .
d4d252 192.168.123.61   Intel Corporate
d89ef3 192.168.123.86   Dell Inc.
dc9fdb 192.168.123.77   Ubiquiti Networks Inc.
dc9fdb 192.168.123.78   .
dcefca 192.168.123.29   Murata Manufacturing Co., Ltd.
e237bd 192.168.123.35
e454e8 192.168.123.95   Dell Inc.
e454e8 192.168.123.93   .
ffffff 192.168.123.255

To your "what to do", try this:

(Invoke-WebRequest -Uri "https://api.macvendors.com/08-BD-43").Content

To you "Sidebar: why does this not work?" question . . .

 | Where-Object {$_.State -ne ('Permanent' -and 'Unreachable')}

Both "Permanent" and "Unreachable" would be seen as strings and the expression "('Permanent' -and 'Unreachable')" would be evaluated -- as a Boolean expression. Both strings are non-empty strings and the result is always going the be $TRUE.

The variable "$_.State" is also a non-empty string so the result of the 1st expression (the one with the "-and" operator) is cast as a string and that value is "TRUE". The result of the entire operation is always going to be $True because the $_State is not equal to "true".

That can be better expressed as:

Where-Object {'Permanent', 'Unreachable' -notcontains $_.State}