constant FEC errors juniper mpc10e 400g
Aaron Gould
aaron1 at gvtc.com
Thu Apr 18 18:45:25 UTC 2024
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 at 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 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
>
--
-Aaron
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