PRP LAN A/B Rx packet counter check on IvS

Products

• VMware NSX

Issue/Introduction

Industrial vSwitch (IvS) can provide network redundancy for industrial ethernet called Profinet by using Parallel Redundancy Protocol (PRP). PRP Dual Attached Node (DAN) and Redundancy Box (RedBox) have two connections for LAN A and LAN B networks and forward the same frames to both netwokrs after duplicating. IvS recieves the duplicated frame on both LAN A and LAN B, then use the frame that arrived first and discard the second one. In the case of the network failuere of LAN A, IvS recieves frames only from LAN B. 

To troubleshoot the network failure, it is required to verify if the IvS receives frames from LAN A and LAN B.

Environment

4.2.x

Resolution

The output of the command “nsxdp-cli ens prp stats node list” has a field “prpRxPkts”. This is a counter for the received frames from an Dual Attached Node (DAN) and it shows separate counters for LAN A and LAN B. If you run the command multiple times and monitor the two counters, you can check if the IvS is receiving frames from the DAN or not. 

 - Get the MAC address of the NIC that is connected Profinet network
 - Login to the ESXi Host via SSH
 - Run the command and find the DvsPortset name for the MAC address
 net-stats -l
 - Run the command and find Switch ID (swID) for the DvsPortset
 nsxcli -c get ens switch list
 - Run the command and find the entry for the MAC address in the node table output
 nsxcli -c get ens prp stats node <swID>
 - Check the prpRxPktsops counters for LAN A and LAN B

You can capture frames on uplinks to analyze what is happening. If you want to check the traffic from a DAN to a Virtual DAN (VDAN), you can follow the steps below.

- Run the command and find the LAN A uplink and LAN B uplink for the vPLC. Uplink information can be found in the fields of lanAUplink and lanBUplink.
 nsxcli -c get ens prp vdan list <swID>
- If you run the pktcap-uw for the vmnic with the filter to limit the frames from the DAN node MAC address, you can see the Profinet frames received from LAN A. Profinet EtherType is 0x8892.
 pktcap-uw --uplink <vmnic> --capture UplinkRcvKernel --srcmac <DAN node MAC Address> -o - | tcpdump-uw -vvv -en -r -