How to capture PRP supervision frames on IvS

Products

• VMware NSX

Issue/Introduction

Industrial vSwitch (IvS) is a feature to enable low latency forwarding for realtime applications. One of the use cases of IvS is a manifacturing factory where the industrial ethernet Profinet is used for the communication between virtuali Programmable Logic Controllers (vPLC) and IO devices. In addition to the low latency forwarding, IvS support redundancy using Parallel Redundancy Protocol (PRP). This KB article describes how to capture the PRP frames on IvS to analyze the redundancy issue.

Environment

The software build that supports IvS feature.
4.2.x

Resolution

IO devices are connected to a Redundancy Box (RedBox). The RedBox processes PRP related protocol handling on behalf of IO devices. IvS also processes PRP on behalf of vPLCs they are running on the ESXi host. This means that actual PRP frames are sending/receiving between IvS and RedBox.

In addition to the PRP data frames, PRP exchanges supervision frames between IvS and RedBox for control plane periodically. In the case of PRP redundancy issue, it is important to check whether IvS is recieving the PRP supervision frames from the RedBox.

Here is the steps to capture the PRP supervision frames on IvS.
- SSH to the ESXi host
- Run the following command to get the vmnic number configured for Profinet (ex. vmnic2)
 nsxcli -c get ens prp config
- Run the packet capture command with vmnic for uplink and ethertype 0x88fb (EtherType of PRP supervision frame is 0x88fb)
 pktcap-uw --uplink vmnic2 --capture UplinkRcvKernel --ethtype 0x88fb --count 3
 (With “--count 3” option, it will display only 3 packets.)

 From the output of this packet capture, you can confirm the PRP supervision frames from the RedBox are arrived at IvS.