ovs-l3ping: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/ovs-l3ping - from package: openvswitch-test

You may install the required package with command apt-get install {package}

Error in other languages:
ovs-l3ping: bevel nie gevind nie
ovs-l3ping: comandă negăsită
ovs-l3ping: comando não encontrado
ovs-l3ping: commande introuvable
ovs-l3ping: command not found
ovs-l3ping: käsku ei ole
ovs-l3ping: không tìm thấy lệnh
ovs-l3ping: komanda nerasta
ovs-l3ping: Kommando nicht gefunden.
ovs-l3ping: kommandot finns inte
ovs-l3ping: komut yok
ovs-l3ping: nie znaleziono polecenia
ovs-l3ping: níor aimsíodh an t-ordú
ovs-l3ping: no se encontró la orden
ovs-l3ping: no s'ha trobat l'ordre
ovs-l3ping: opdracht niet gevonden
ovs-l3ping: parancs nem található
ovs-l3ping: perintah tidak ditemukan
ovs-l3ping: príkaz nenájdený
ovs-l3ping: příkaz nenalezen
ovs-l3ping: команда не найдена
ovs-l3ping: командата не е открита
ovs-l3ping: 命令找不到
ovs-l3ping: コマンドが見つかりません