constant FEC errors juniper mpc10e 400g

Thu Apr 18 17:33:52 UTC 2024

Not to belabor this, but so interesting... I need a FEC-for-Dummies or FEC-for-IP/Ethernet-Engineers...

Shown below, my 400g interface with NO config at all... Interface has no traffic at all, no packets at all....  BUT, lots of FEC hits.  Interesting this FEC-thing.  I'd love to have a fiber splitter and see if wireshark could read it and show me what FEC looks like...but something tells me i would need a 400g sniffer to read it, lol

It's like FEC (fec119 in this case) is this automatic thing running between interfaces (hardware i guess), with no protocols and nothing needed at all in order to function.

-Aaron

{master}
me at mx960> show configuration interfaces et-7/1/4 | display set

{master}
me at mx960>

{master}
me at mx960> clear interfaces statistics et-7/1/4

{master}
me at mx960> show interfaces et-7/1/4 | grep packet
     Input packets : 0
     Output packets: 0

{master}
me at mx960> show interfaces et-7/1/4 | grep "put rate"
   Input rate     : 0 bps (0 pps)
   Output rate    : 0 bps (0 pps)

{master}
me at mx960> show interfaces et-7/1/4 | grep rror
   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                28209
     FEC Uncorrected Errors                  0
     FEC Corrected Errors Rate            2347
     FEC Uncorrected Errors Rate             0

{master}
me at mx960> show interfaces et-7/1/4 | grep packet
     Input packets : 0
     Output packets: 0

{master}
me at mx960> show interfaces et-7/1/4 | grep "put rate"
   Input rate     : 0 bps (0 pps)
   Output rate    : 0 bps (0 pps)

{master}
me at mx960> show interfaces et-7/1/4 | grep rror
   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                45153
     FEC Uncorrected Errors                  0
     FEC Corrected Errors Rate              29
     FEC Uncorrected Errors Rate             0

{master}
me at mx960> show interfaces et-7/1/4 | grep packet
     Input packets : 0
     Output packets: 0

{master}
me at mx960> show interfaces et-7/1/4 | grep "put rate"
   Input rate     : 0 bps (0 pps)
   Output rate    : 0 bps (0 pps)

{master}
me at mx960> show interfaces et-7/1/4 | grep rror
   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                57339
     FEC Uncorrected Errors                  0
     FEC Corrected Errors Rate            2378
     FEC Uncorrected Errors Rate             0

{master}
me at mx960>

On 4/18/2024 7:13 AM, Mark Tinka wrote:
>
>
> On 4/17/24 23:24, Aaron Gould wrote:
>
>> Well JTAC just said that it seems ok, and that 400g is going to show 
>> 4x more than 100g "This is due to having to synchronize much more to 
>> support higher data."
>>
>
> We've seen the same between Juniper and Arista boxes in the same rack 
> running at 100G, despite cleaning fibres, swapping optics, moving 
> ports, moving line cards, e.t.c. TAC said it's a non-issue, and to be 
> expected, and shared the same KB's.
>
> It's a bit disconcerting when you plot the data on your NMS, but it's 
> not material.
>
> Mark.

-- 
-Aaron
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