[j-nsp] interpreting 10Gb interface "PCS statistics" values

David B Funk dbfunk at engineering.uiowa.edu
Wed Oct 19 19:40:24 EDT 2016

I've got a couple of 10Gig-eth interfaces (xe- on MX480) of which I'm trying to 
interpret the "PCS statistics" values.

One of them is pretty steady at:

   PCS statistics                      Seconds
     Bit errors                             4
     Errored blocks                         4

The other one seems to vary with the values ranging from 10 to 70.

   PCS statistics                      Seconds
     Bit errors                            61
     Errored blocks                        69

The second interface will will trigger a number of error conditions at the 
other end which terminates in a Cisco router with out showing any error 
conditions at my end (EG BPDU Error: None, MAC-REWRITE Error: None, CRC/Align 
errors 0, FIFO errors 0, etc..) During some of these times I'll see significant 
packet loss and others see minimal problems.

According to Juniper docs the PCS statistics should mean:

  PCS statistics
   (10-Gigabit Ethernet interfaces) Displays Physical Coding Sublayer (PCS) fault
   conditions from the WAN PHY or the LAN PHY device.

     Bit errors—High bit error rate. Indicates the number of bit errors when the
       PCS receiver is operating in normal mode.
     Errored blocks—Loss of block lock. The number of errored blocks when PCS
       receiver is operating in normal mode.

But I don't know how to interpret a value of "16 seconds" with that definition.
Can anybody shed some light on what those numbers mean.


Dave Funk                                  University of Iowa
<dbfunk (at) engineering.uiowa.edu>        College of Engineering
319/335-5751   FAX: 319/384-0549           1256 Seamans Center
Sys_admin/Postmaster/cell_admin            Iowa City, IA 52242-1527
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