CPwE Parallel Redundancy Protocol Monitoring and Troubleshooting
This chapter describes management tools and diagnostic information available to monitor and troubleshoot PRP status and operation, including DANs, VDANs, and RedBox IES.
PRP information can be obtained using Stratix IES Device Manager, Cisco CLI commands, Studio 5000 Logix Designer Add-on Profiles (AOP), CIP message diagnostic and IACS device webpages.
This section provides PRP information available from a RedBox IES via Device Manager webpage or CLI commands.
Stratix RedBox IES provides information about connected VDANs on the Device Manager Monitor->Status ->PRP page. The VDAN MAC addresses are learned automatically from the switch MAC table. The RedBox IES sends PRP supervisory frames for each VDAN via the PRP channel ports.
Figure 4-1 VDAN Table
RedBox IES learns about DANs and SANs in the network from the supervisory frames received on the PRP channel ports. These frames are propagated within a VLAN as special Layer 2 multicast frames.
The DAN and SAN information can be viewed on the Monitor->Status->PRP page.
Figure 4-2 Node Table
- Time To Live (TTL) value shows the number of seconds since the last received frame. Node entries age out and are removed from the tables after 60 seconds.
- The switch supports a maximum of 512 SAN and DAN entries in the Node table. If the Node table is full, the switch treats new nodes as a DAN by default.
- The switch supports a maximum of 512 VDAN entries in the VDAN table. If the VDAN table is full, the switch cannot send supervisory frames for new VDANs.
- In a multi-VLAN network with PRP channel ports in the trunk mode, the RedBox IES receives supervisory frames and displays information about nodes in all VLANs enabled on the trunk
- The number of DAN packets received from LAN A and LAN B should be the same or very close in a normally functioning network. The increasing difference may be due to dropping packets in one of the LANs and may require further troubleshooting.
- There should be no Wrong Packets entries. If any exist and are increasing, this indicates incorrect cabling of a DAN or a RedBox.
Note DANs, SANs, and VDANs can be manually added to and deleted from the corresponding tables on the Configure->PRP page. Normally dynamic learning should be sufficient. Static configuration may be needed only if PRP devices do not support supervisory frames.
Command Line Interface
CLI diagnostics commands for PRP provide more detailed information for troubleshooting.
PRP-IES-RB1#show prp statistics egressPacketStatistics
PRP channel-group 1 EGRESS STATS:
duplicate packet: 2308893385
supervision frame sent: 7883182
packet sent on lan a: 2308893377
packet sent on lan b: 2308890642
byte sent on lan a: 389844980047
byte sent on lan b: 389924896911
egress packet receive from switch: 2309098088
- show prp statistics egress command shows detailed packet counts and byte counts for transmitted frames over the PRP channel.
PRP-IES-RB1#show prp statistics ingressPacketStatistics
PRP channel-group 1 INGRESS STATS:
ingress pkt lan a: 2503748276
ingress pkt lan b: 2503792103
ingress danp pkt acpt: 2449954701
ingress danp pkt dscrd: 2449759968
ingress supfrm rcv a: 53914548
ingress supfrm rcv b: 53914032
ingress pri over pkt a: 0
ingress pri over pkt b: 0
ingress oversize pkt a: 0
ingress oversize pkt b: 0
ingress byte lan a: 530416337651
ingress byte lan b: 530510451733
ingress wrong lan id a: 0
ingress wrong lan id b: 0
ingress warning count lan a: 1
ingress warning count lan b: 0
ingress unique count a: 105123619610672
ingress unique count b: 377957242996
ingress duplicate count a: 2449759973
ingress duplicate count b: 2449759973
ingress multiple count a: 0
ingress multiple count b: 0
- show prp statistics ingress command shows detailed packet counts and byte counts for different types of frames received on the PRP channel.
- Ingress Warning status indicates following conditions for LAN A or LAN B:
– Loss of communication for three seconds on one LAN, but not the other. This condition applies to traffic from all nodes. The condition is cleared once communication is restored for three seconds.
– Node status is active on one LAN but not the other. This means that no packets were received from one of the PRP nodes in the switch table (DANs or VDANs) on one of the LANs for three seconds. The condition is cleared once packets are received again within three seconds.
– Packets from a wrong LAN were received on one of the ports in the past second. The condition is cleared once no wrong packets are received for one second.
– Warning counts and wrong LAN counts show total number of faults since the last reset of counters.
PRP-IES-RB1#show prp statistics ingressPacketStatistics
ingress wrong lan id a: 12
ingress wrong lan id b: 2
ingress warning count lan a: 8
ingress warning count lan b: 3
PRP-IES-RB1#show prp statistics ptpPacketStatistics
PRP channel-group 1 PTP STATS:
- show prp statistics ptp command displays PTP traffic counters for the PRP channel (which is sent and received independently on each port, bypassing PRP duplication mechanism).
PRP-IES-RB1#clear prp statistics
- clear prp statistics command resets all PRP counters and could be useful when troubleshooting an ongoing problem with PRP communication.
- show prp node-table statistics command provide warning status and received count per LAN for each PRP node learned by the RedBox, including DANs, SANs, remote VDANs, and other RedBoxes.
Figure 4-3 Node Table Statistics
Studio 5000 Logix Designer
Studio 5000 Logix Designer Add-on Profile provides PRP diagnostics, counters, and node information for PRP-enabled devices in the controller I/O tree.
The AOP for a Stratix RedBox IES displays PRP warning status and total counters for the PRP channel. This information is available in the AOP for Stratix IOS version 15.2(6)E2a or later.
Figure 4-4 Stratix AOP
The AOP for a PRP EtherNet/IP module displays the PRP network status, total counters, and the node table with node status. IP addresses are displayed for PRP nodes in the I/O tree, otherwise only MAC addresses are shown.
Below is an example of the PRP status page for the 1756-EN2TP module.
Figure 4-5 EN2TP Module AOP
The AOP for the FLEX 5000TM EtherNet/IP adapter also includes a last PRP fault time stamp data (connection type “Status with PRP”).
Figure 4-6 Flex 5000 Module AOP
The PRP warning status for a PRP EtherNet/IP module or a RedBox can be obtained by the controller program by sending a CIP message to the device. Parameters for the message instruction are shown in Table 4-1 .
Table 4-1 CIP Message Parameters for PRP Status
Get Attribute Single
11 (Hex) for LAN A
12 (Hex) for LAN B
Figure 4-7 CIP Message
Note PRP-enabled EtherNet/IP modules also provide PRP diagnostics via webpages, similar to data available in the AOP. Depending on the platform and the firmware version, web access to the module may need to be enabled explicitly.