Re: constant FEC errors juniper mpc10e 400g

[Aaron Gould <aaron1 () gvtc com>]

Thanks.  What "all the ethernet control frame juju" might you be 
referring to?  I don't recall Ethernet, in and of itself, just sending 
stuff back and forth.  Does anyone know if this FEC stuff I see 
concurring is actually contained in Ethernet Frames?  If so, please send 
a link to show the ethernet frame structure as it pertains to this 400g 
fec stuff.  If so, I'd really like to know the header format, etc.

-Aaron

On 4/18/2024 1:17 PM, Tom Beecher wrote:
> FEC is occurring at the PHY , below the PCS.
>
> Even if you're not sending any traffic, all the ethernet control frame 
> juju is still going back and forth, which FEC may have to correct.
>
> I *think* (but not 100% sure) that for anything that by spec requires 
> FEC, there is a default RS-FEC type that will be used, which *may* be 
> able to be changed by the device. Could be fixed though, I honestly 
> cannot remember.
>
> On Thu, Apr 18, 2024 at 1:35 PM Aaron Gould <aaron1 () gvtc com> wrote:
>
>     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@mx960> show configuration interfaces et-7/1/4 | display set
>
>     {master}
>     me@mx960>
>
>     {master}
>     me@mx960> clear interfaces statistics et-7/1/4
>
>     {master}
>     me@mx960> show interfaces et-7/1/4 | grep packet
>          Input packets : 0
>          Output packets: 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 | 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@mx960> show interfaces et-7/1/4 | grep packet
>          Input packets : 0
>          Output packets: 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 | 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@mx960> show interfaces et-7/1/4 | grep packet
>          Input packets : 0
>          Output packets: 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 | 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@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
--
-Aaron