FEC on 400G is required and expected. As long as it is “corrected”, you have
nothing to worry about. We had the same realisation recenty when upgrading to
400G.
-Schylar
From: NANOG on behalf of Aaron
Gould
Date: Wednesday, April 17, 2024 at 2:38 PM
To: nanog@nanog.org
Subject: constant FEC errors juniper mpc10e 400g
We recently added MPC10E-15C-MRATE cards to our MX960's to upgrade our core to
400g. During initial testing of the 400g interface (400GBASE-FR4), I see
constant FEC errors. FEC is new to me. Anyone know why this is occurring?
Shown below, is an interface with no traffic, but seeing constant FEC errors.
This is (2) MX960's cabled directly, no dwdm or anything between them... just a
fiber patch cable.
{master}
me@mx960> clear interfaces statistics et-7/1/4
{master}
me@mx960> show interfaces et-7/1/4 | grep rror | refresh 2
---(refreshed at 2024-04-17 14:18:53 CDT)---
Link-level type: Ethernet, MTU: 1514, MRU: 1522, Speed: 400Gbps, BPDU Error:
None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering:
Disabled,
Bit errors 0
Errored blocks 0
Ethernet FEC statistics Errors
FEC Corrected Errors0
FEC Uncorrected Errors 0
FEC Corrected Errors Rate 0
FEC Uncorrected Errors Rate 0
---(refreshed at 2024-04-17 14:18:55 CDT)---
Link-level type: Ethernet, MTU: 1514, MRU: 1522, Speed: 400Gbps, BPDU Error:
None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering:
Disabled,
Bit errors 0
Errored blocks 0
Ethernet FEC statistics Errors
FEC Corrected Errors 4302
FEC Uncorrected Errors 0
FEC Corrected Errors Rate 8
FEC Uncorrected Errors Rate 0
---(refreshed at 2024-04-17 14:18:57 CDT)---
Link-level type: Ethernet, MTU: 1514, MRU: 1522, Speed: 400Gbps, BPDU Error:
None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering:
Disabled,
Bit errors 0
Errored blocks 0
Ethernet FEC statistics Errors
FEC Corrected Errors 8796
FEC Uncorrected Errors 0
FEC Corrected Errors Rate 146
FEC Uncorrected Errors Rate 0
---(refreshed at 2024-04-17 14:18:59 CDT)---
Link-level type: Ethernet, MTU: 1514, MRU: 1522, Speed: 400Gbps, BPDU Error:
None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering:
Disabled,
Bit errors 0
Errored blocks 0
Ethernet FEC statistics Errors
FEC Corrected Errors15582
FEC Uncorrected Errors 0
FEC Corrected Errors Rate 111
FEC Uncorrected Errors Rate 0
---(refreshed at 2024-04-17 14:19:01 CDT)---
Link-level type: Ethernet, MTU: 1514, MRU: 1522, Speed: 400Gbps, BPDU Error:
None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering:
Disabled,
Bit errors 0
Errored blocks 0
Ethernet FEC statistics Errors
FEC Corrected Errors20342
FEC Uncorrected Errors 0
FEC Corrected Errors Rate 256
FEC Uncorrected Errors Rate 0
{master}
me@mx960> show interfaces et-7/1/4 | grep "put rate"
Input rate : 0 bps (0 pps)
Output rate: 0 bps (0 pps)
{master}
me@mx960> show interfaces et-7/1/4
Physical interface: et-7/1/4, Enabled, Physical link is Up
Interface index: 226, SNMP ifIndex: 800
Link-level type: Ethernet, MTU: 1514, MRU: 1522, Speed: 400Gbps, BPDU Error:
None, Loop Detect PDU Error: None, Loopback: Disabled, Source filtering:
Disabled,
Flow control: Enabled
Pad to minimum frame size: Disabled
Device flags : Present Running
Interface flags: SNMP-Traps Internal: 0x4000
Link flags : None
CoS queues : 8 supported, 8 maximum usable queues
Schedulers : 0
Last flapped : 2024-04-17 13:55:28 CDT (00:36:19 ago)
Input rate : 0 bps (0 pps)
Output rate: 0 bps (0 pps)
Active alarms : None
Active defects : None
PCS statistics Seconds
Bit errors 0
Errored blocks 0
Ethernet FEC Mode : FEC119
Ethernet FEC statistics Errors
FEC Corrected Errors 801787
FEC Uncorrected Errors 0
FEC Corrected Errors Rate2054
FEC Uncorrected Errors Rate 0
Link Degrade :
Link Monitoring : Disable
Interface transmit statistics: Disabled
Logical
