- Platform compatibility
- Show commands
- Syslog messages
- Link issues
- Fiber Cleaning
400GBASE-ZR transceiver is the industry’s first multi-vendor DWDM standard, a Digital Coherent Optical module with tunable laser, using DWDM multiplexing and 16QAM modulation and capable of delivering 400G per port over distances up to 120 km. 400GBASE-ZR transceivers are fully interoperable, their functionality and management are specified by CMIS4.0 and subsequent CMIS versions, Coherent 400ZR and Coherent CMIS Implementation Agreements [1,2,3,4] and other OIF documents. On the line side, the module is utilizing a high-performance Concatenated forward-error correction (C-FEC) scheme, which consists of a hard-decision (HD) outer FEC and a soft-decision (SD) inner FEC. 400GBASE-ZR transceivers are available in both QSFP-DD and OSFP form factors
Key software features supported by Arista EOS in 4.25.2F:
- Compliant with CMIS4.0/CMIS4.1 (CMIS5.0) and Coherent CMIS
- Frequency tuning (100GHz and 75GHz grids)
- DOM monitoring, including VDM (Versatile Diagnostics Monitoring) pages, defined in CMIS4.0
- Coherent alarms and faults, including pages, defined by Coherent CMIS
- Configurable Tx output power
- A separate command for shutting down Tx output path for unidirectional mode
- 1-sec update of pre-FEC BER, OSNR, ESNR
The 400GBASE-ZR transceiver is a power class 8 module with power consumption up to 20W, the highest power consumption among 400G transceivers.
In theory, every 400GBASE OSFP or QSFP-DD switch is qualified to host 400GBASE-ZR transceivers. However, the actual number of 400GBASE-ZR modules that can be plugged in the switch simultaneously may vary, depending on platform (modular vs fixed) and ASIC type. It is always recommended to discuss installation of 400GBASE-ZR modules with Arista support.
Using 400GBASE-ZR in combination with OSFP-LS
Arista EOS allows using OSFP-LS (pluggable line system in the OSFP form factor), instead of traditional DCI line systems. For more details on OSFP-LS and their integration with 400GBASE-ZR, refer to the OSFP-LS TOI.
Laser Frequency Configuration
All coherent modules, including 400GBASE-ZR, require their laser frequency to be explicitly configured. To configure laser frequency in 400GBASE-ZR, use the ‘transceiver frequency’ command under the defined interface, providing frequency in Gigahertz, in the range 191.3-196.1 THz. If laser frequency is not configured or is configured outside the valid range, all interfaces associated with the port are put into errdisable state.
switch#conf switch(config)# switch(config)#interface Ethernet12/1 switch(config-if-Et12/1)#transceiver frequency 193100 switch(config-if-Et12/1)#
Configured and operational frequency settings can be verified using the CLI command “show interface [<intf>] transceiver hardware”
- It can take up to 90 sec for the 400GBASE-ZR module to fully complete frequency tuning.
- The frequency plan for 400GBASE-ZR modules support channel spacings of 100GHz or 75GHz. It is recommended to use operating frequency channel definitions in chapter 15 of .
For additional information on frequency configuration for DCO modules, see Configuration and Status sections in .
Transmit Output Power Configuration
CMIS4.0 defines support of configurable transmit output power as an optional feature. Check the output of CLI command ‘show interface [<intf>] transceiver eeprom’ for page 04h, registers 196-201 to see if it is supported.
Programmable output power advertisement (04h:196-201): Lane programmable output power supported (04h:196): true Min programmable output power (04h:198-199): -14 dB Max programmable output power (04h:200-201): -10 dB
Transmit Output Power can be configured using ‘transceiver transmitter signal power’ command
switch#conf switch(config)#interface Ethernet14/1 switch(config-if-Et14/1)#transceiver transmitter signal-power ? switch(config-if-Et14/1)#transceiver transmitter signal-power -10
Configured Tx Power can be verified through the CLI command “show interface [<intf>] transceiver hardware”. Actual operational Tx Power can be verified with CLI command “show interface [<intf>] transceiver”
Note 1: 400GBASE-ZR does not have a recommended level of transmit laser power. In most cases, it is OK to stay with default power.
Note 2: Some vendors may not populate the range of supported output power correctly. The range -10 to -14 dBm should be supported. Contact Arista Support if you are planning to configure output power outside of this range.
Transmit Output Disable and Unidirectional mode
In the coherent optics, ‘shutdown’ command impacts both transmit and receive path and can’t be used to set up unidirectional mode. To shut down Tx output path, use command ‘transceiver transmitter disabled’:
switch#conf switch(config)#interface Ethernet14/1 switch(config-if-Et14/1)#transceiver transmitter DISABLED
To re-enable transmit output, use the ‘no’ or ‘default’ version of the above configuration command.
‘Show interface transceiver eeprom’ command – module capabilities
show interface [<intf>] transceiver eeprom – displays parsed capabilities. For 400GBASE-ZR, parsing of frequency tuning, power tuning ( page 04h ) and VDM configuration pages (20h-23h) is added.
switch#show interface Ethernet15/1 transceiver eeprom Ethernet15 EEPROM: ... Frequency tuning support (04h:128-129): Grid spacing capabilities (04h:128): 100 GHz grid supported (04h:128): true 12.5 GHz grid supported (04h:128): false 25 GHz grid supported (04h:128): false 3.125 GHz grid supported (04h:128): false 33 GHz grid supported (04h:128): false 50 GHz grid supported (04h:128): false 6.25 GHz grid supported (04h:128): false 75 GHz grid supported (04h:128): true Tunable wavelength (04h:128): true Fine tuning support (04h:129): false Supported channel boundaries (04h:130-161): 100 GHz grid (04h:150-153): Lowest channel (04h:150-151): -18 Lowest frequency (04h:150-151): 191300000 MHz Highest channel (04h:152-153): 30 Highest frequency (04h:152-153): 196100000 MHz 75 GHz grid (04h:158-161): Lowest channel (04h:158-159): -72 Lowest frequency (04h:158-159): 191300000 MHz Highest channel (04h:160-161): 120 Highest frequency (04h:160-161): 196100000 MHz Programmable output power advertisement (04h:196-201): Lane programmable output power supported (04h:196): false VDM configuration (20h:128-255;21h:128-255): VDM group 1 (20h:128-255): Parameter 1 (20h:128-129): Lane (20h:128): 0 Threshold ID (20h:128): 0 Parameter type (20h:129): Laser temperature Parameter 3 (20h:132-133): Lane (20h:132): 0 Threshold ID (20h:132): 2 Parameter type (20h:133): eSNR host input Parameter 4 (20h:134-135): Lane (20h:134): 1 Threshold ID (20h:134): 2 Parameter type (20h:135): eSNR host input Parameter 5 (20h:136-137): Lane (20h:136): 2 Threshold ID (20h:136): 2 Parameter type (20h:137): eSNR host input ... Parameter 84 (21h:166-167): Lane (21h:166): 0 Threshold ID (21h:166): 14 Parameter type (21h:167): MER Number of VDM groups supported (2Fh:128): 2
“Show interface transceiver dom” command – current performance data
show interface [<intf>] transceiver dom – displays the most important current performance data on the media (line) side
switch#show interface Ethernet11/1 transceiver dom Ch: Channel, N/A: not applicable, TX: transmit, RX: receive mA: milliamperes, dBm: decibels (milliwatts), C: Celsius, V: Volts Port 11 Last update: 0:00:05 ago Value ---------------- Case temperature 66.59 C Voltage 3.26 V TX power -10.23 dBm RX total power -11.61 dBm RX channel power -11.94 dBm Pre-FEC BER 1.82e-03 Post-FEC errored frames ratio 0.00e+00 Chromatic dispersion (short link) 0.00 ps/nm Chromatic dispersion (long link) 0.00 ps/nm Differential group delay 9.31 ps SOPMD 0.00 ps^2 Polarization dependent loss 0.40 dB Received OSNR estimate 35.10 dB Received ESNR estimate 17.50 dB Carrier frequency offset 0.00 MHz Error vector magnitude 100.00 % SOP rate of change 0.00 krad/s Laser temperature 59.54 C Laser frequency 193100.00 GHz
- BER: Bit Error Rate
- FEC: Forward Error Correction
- OSNR: Optical Signal to Noise Ratio
- ESNR: Electrical Signal to Noise Ratio
- SOP: State of Polarization
- SOPMD: State of Polarization Mode Dispersion
“Show transceiver status interface” command – alarms, faults, and interface status
show transceiver status interface [<intf>] – displays the most important alarms, faults and interface status.
For 400GBASE-ZR modules, media and host side coherent alarms, host-side pre-FEC BER, defined in the Coherent CMIS and post-FEC BER have been added to the command’s output:
switch#show transceiver status interface Ethernet14/1 Current State Changes Last Change ------------- ------- ----------- Port 14 Transceiver 400GBASE-ZR 1 0:15:09 ago Transceiver SN 200554050 Presence present Adapters none Bad EEPROM checksums 0 never Resets 0 0:15:14 ago Interrupts 0 never Data path firmware fault ok 0 never Module firmware fault ok 0 never Temperature high alarm ok 0 never Temperature high warn ok 0 never Temperature low alarm ok 0 never Temperature low warn ok 0 never Voltage high alarm ok 0 never Voltage high warn ok 0 never Voltage low alarm ok 0 never Voltage low warn ok 0 never Module state ready 4 0:14:55 ago Data path 1 state activated 4 0:07:21 ago Data path 2 state activated 4 0:07:21 ago Data path 3 state activated 4 0:07:21 ago Data path 4 state activated 4 0:07:21 ago Data path 5 state activated 4 0:07:21 ago Data path 6 state activated 4 0:07:21 ago Data path 7 state activated 4 0:07:21 ago Data path 8 state activated 4 0:07:21 ago RX LOS ok 2 0:05:54 ago TX fault ok 0 never RX CDR LOL ok 0 never TX power high alarm ok 0 never TX power high warn ok 2 0:07:39 ago TX power low alarm ok 2 0:07:50 ago TX power low warn ok 4 0:07:39 ago TX bias high alarm ok 0 never TX bias high warn ok 0 never TX bias low alarm ok 0 never TX bias low warn ok 0 never RX power high alarm ok 0 never RX power high warn ok 0 never RX power low alarm ok 0 never RX power low warn ok 0 never TX loss of alignment ok 0 never TX out of alignment ok 0 never TX clock monitor unit LOL ok 0 never TX reference clock LOL ok 0 never TX deskew LOL ok 0 never TX FIFO error ok 0 never RX demodulator LOL ok 0 never RX CD compensation LOL ok 0 never RX loss of alignment ok 0 never RX out of alignment ok 0 never RX deskew LOL ok 0 never RX FIFO error ok 0 never RX FEC excessive degrade ok 0 never RX FEC detected degrade ok 0 never Freq tuning in progress idle 0 never Freq tuning busy ok 0 never Freq tuning invalid channel ok 0 never Freq tuning completed no 2 0:07:34 ago Ethernet14/1 Operational speed 400Gbps Pre-FEC bit error rate 0.00e+00 Post-FEC errored frames ratio 0.00e+00 TX LOS Host lane 1 ok 0 never Host lane 2 ok 0 never Host lane 3 ok 0 never Host lane 4 ok 0 never Host lane 5 ok 0 never Host lane 6 ok 0 never Host lane 7 ok 0 never Host lane 8 ok 0 never TX CDR LOL Host lane 1 ok 0 never Host lane 2 ok 0 never Host lane 3 ok 0 never Host lane 4 ok 0 never Host lane 5 ok 0 never Host lane 6 ok 0 never Host lane 7 ok 0 never Host lane 8 ok 0 never TX adaptive input EQ fault Host lane 1 ok 0 never Host lane 2 ok 0 never Host lane 3 ok 0 never Host lane 4 ok 0 never Host lane 5 ok 0 never Host lane 6 ok 0 never Host lane 7 ok 0 never Host lane 8 ok 0 never
Note: in the operational state, module state is ‘Ready’ and datapath state for all 8 lanes is ‘activated’
“Wavelength/frequency and output power status”
The ‘show interface [<intf>] transceiver hardware’ command displays the configured and programmed wavelength and output power. It takes a short time for the configured wavelength or output power to be programmed into the transceiver. The configured wavelength/output power and programmed wavelength/output power should not differ for extended periods of time.
switch#show interface Ethernet23/1 trans hardware Name: Et23/1 Media type: 400GBASE-ZR Maximum module power (W): 20.0 Maximum slot power (W): 20.0 Configured frequency (GHz): 193100.0 Computed wavelength (nm): 1552.52 Operational frequency (GHz): 193,100.0 Operational wavelength (nm): 1552.52 Configured TX power (dBm): -10.0 Operational TX power (dBm): -10.0
Note: configured transmit output power and operational transmit output power are only displayed if configurable output power is supported by the module.
- Check transceiver type – make sure it is 400GBASE-ZR
- Check peer transceiver – make sure it is also 400GBASE-ZR.
- Check that channel/frequency is configured and interfaces are not in errdisabled state
- Check that the selected frequency is matching on both sides of the optical link
- Check that transmit output is not disabled
- If Tx power is not configured, check that it is in the range of -6 dB to -12 dB.
- If Tx power is configured, check that matches its configured values on both sides of the optical link.
- Check Rx power. The best performance of an optical link is achieved when the received power is -10dB.
- Collect the output of CLI commands listed in the “Show commands” section before making a request for support from the development team.
- Check that pre-FEC BER ( ‘show transceiver dom’ command ) is in the correctable range ( less than 1e-2 ).
- ‘show transceiver status interface’ – check that module state is ‘Ready’, datapath state is ‘Activated’. Check for possible alarms and faults
If a link has issues, the following commands and files are useful for debugging and Arista TAC.
- show interfaces <interfaceName> phy detail
- show interfaces <interfaceName> transceiver detail
- show idprom transceiver <interfaceName> ext
- files in /var/log/agents/*
- files in /var/log/qt/*
See  for recommended best practices of fiber cleaning.
400GBASE-ZR transceivers are relatively new. The modules could be Arista branded or 3rd party, from multiple vendors. For 3rd party optics, some optional properties (Tx output power, support of 75GHz grid) or DOM properties in the VDM pages, may not be implemented.
- Common Management Interface Specification ( CMIS4.0 )
- Common Management Interface Specification draft ( CMIS4.1 )
- OIF Implementation Agreement for Coherent CMIS, rev1.1
- OIF Implementation Agreement for 400ZR, OIF-400ZR-01.0
- CFP2-DCO configuration, status and troubleshooting
- Arista Networks: Data Center Interconnect – Simplified
- Arista Networks: Fiber Cleaning Application Note