In my reading the 400GBASE-R Physical Coding Sublayer (PCS) always includes the FEC. This is defined in clause 119 of IEEE Std 802.3-2022, and most easily seen in "Figure 119–2—Functional block diagram" if you don't want to get buried in the prose. Nothing there seems to imply that the FEC is optional. I'd be happy to be corrected though. It may well be that there is a method to reading these tomes, that I have not discovered yet. It is the first time I dove deep into any IEEE standard. Best regards Joel On 17.04.2024 21:47, Tom Beecher wrote:
Isn't FEC required by the 400G spec?
On Wed, Apr 17, 2024 at 3:45 PM Aaron Gould <aaron1@gvtc.com <mailto:aaron1@gvtc.com>> wrote:
__
i did. Usually my NANOG and J-NSP email list gets me a quicker solution than JTAC.
-Aaron
On 4/17/2024 2:37 PM, Dominik Dobrowolski wrote:
Open a JTAC case, That looks like a work for them
Kind Regards, Dominik
W dniu śr., 17.04.2024 o 21:36 Aaron Gould <aaron1@gvtc.com <mailto:aaron1@gvtc.com>> napisał(a):
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 Errors 0 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 Errors 15582 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 Errors 20342 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 Rate 2054 FEC Uncorrected Errors Rate 0 Link Degrade : Link Monitoring : Disable Interface transmit statistics: Disabled
Logical interface et-7/1/4.0 (Index 420) (SNMP ifIndex 815) Flags: Up SNMP-Traps 0x4004000 Encapsulation: ENET2 Input packets : 1 Output packets: 1 Protocol inet, MTU: 1500 Max nh cache: 75000, New hold nh limit: 75000, Curr nh cnt: 1, Curr new hold cnt: 0, NH drop cnt: 0 Flags: Sendbcast-pkt-to-re Addresses, Flags: Is-Preferred Is-Primary Destination:10.10.10.76/30 <http://10.10.10.76/30>, Local: 10.10.10.77, Broadcast: 10.10.10.79
-- -Aaron
-- -Aaron
-- Joel Busch, Network SWITCH Werdstrasse 2, P.O. Box, 8021 Zurich, Switzerland phone +41 44 268 15 30, direct +41 44 268 16 58