This article provides more information about the pfebm_devrt_entry_change and pfebm_vcp_select syslog messages that are sometimes seen on an MX-VC node. As stated, the messages are indicative of a process being invoked and not of an error. Hence, these messages can be ignored.

Customers may sometimes see the following log messages on an MX-VC node:

Jun 21 02:09:19.934 2021  mx-vc-2028-2029-member1-re0 : %PFE-6: member1-fpc10 pfebm_devrt_entry_change: OP:Change for L:0, R:0, G:1, M:0 for M:1 IFD 0x0

Jun 21 02:09:19.937 2021  MX-VC-BNG01-member1-re0 : %PFE-6: member1-fpc10 pfebm_vcp_select: duplicate slot entry vcp dev_num:33 port_num:0 ifd_idx:130 ifl_idx:64
Jun 21 02:09:19.987 2021  MX-VC-BNG01-member1-re0 : %PFE-6: member1-fpc10 pfebm_vcp_select: duplicate slot entry vcp dev_num:59 port_num:0 ifd_idx:132 ifl_idx:67
Jun 21 02:09:20.113 2021  MX-VC-BNG01-member1-re0 : %PFE-6: member1-fpc10 pfebm_vcp_select: selected vc port ifd_idx:131

pfebm_vcp_select is a function that is used to select the Packet Forwarding Engine's VCP control port. It is invoked by the pfebm_devrt_entry_change function, which is invoked by the devrt update process. This means that if the devrt (Device Route Table) update process has been initiated, the pfebm_devrt_entry_change and pfebm_vcp_select functions will be invoked subsequently. This is when the above logs can be seen.

A devrt update can be triggered when a non-VCP FPC or VCP FPC is rebooted or there is a VCP interface state change. Reboot of a non-VCP FPC can trigger a devrt update on both members, which then leads to the pfebm_devrt_entry_change and pfebm_vcp_select functions being invoked. This is expected behavior.

• If a non-VCP FPC is rebooted, because the state of the VCP interfaces does not change, the PFE VCP control port for one FPC will not change.

  • Here there is no VCP link state change, so there will be no impact (FPC reboot is not taken into account in this case).

• If a VCP FPC is rebooted or the state of the VCP interfaces changes, the PFE VCP control port for one FPC might be different from the previous one.

  • Here there is a VCP link state change, so some packet loss might be seen during the VCP flap and the PFE VCP control port change process, but normally this packet loss is minimal to be noticed.

The log message " pfebm_vcp_select: duplicate slot entry vcp dev_num:33 port_num:0 ifd_idx:130 ifl_idx:64 " does not indicate an error condition. In the PFE Backplane Management Ethernet (BMEB), only one VCP in each slot is considered (part of the load balancing algorithm) for host path traffic forwarding to the other chassis. So during each devrt update, the first VCP in the update will be made the active VCP link. The subsequent entries are not considered and are logged as " duplicate slot entry vcp ".

The log message pfebm_devrt_entry_change means that this is an update from member 0 to member 1.

Jun 21 02:09:19.934 2021  mx-vc-2028-2029-member1-re0 : %PFE-6: member1-fpc10 pfebm_devrt_entry_change: OP:Change for L:0, R:0, G:1, M:0 for M:1 IFD 0x0 <<< (M:0 for M:1) means the update is from member 0 to member 1    

In the following log, the devrt update is from member 1 to member 0.   

Jun 23 02:18:02.950 2021  mx-vc-2028-2029-member0-re0 : %PFE-6: member0-fpc7 pfebm_devrt_entry_change: OP:Change for L:0, R:1, G:0, M:1 for M:0 IFD 0x0 <<< (M:1 for M:0) means the update is from member 1 to member 0

These messages are indicative of a process being invoked (the devrt update process). They do not indicate any errors and can be safely ignored.