• Understanding interface breakout modes on Arista switches

 
 
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Arista switches have the capability to break out QSFP and OSFP interfaces to multiple lanes of smaller speeds. This can be very useful for high density deployments that require a minimal RU footprint by maximizing the ports available on various Arista platforms. With QSFP interfaces, whether it be for 40G or 100G speeds, these are implemented as 4 lanes that can be independently controlled & configured. With 40G interfaces, these interfaces can operate in 4x10G speeds and for 100G interfaces can operate in 4x25G or 2x50G speeds .       

As an example, with the Arista 7280CR2A-30 switch which comes with 30 QSFP interfaces, these interfaces can operate in 40G or 100G speeds natively or each individual port can be broken out into 4x10G or 4x25G modes to provide 120 unique interfaces. As a note with 100G interfaces, 40G operation can be achieved by utilizing the correct QSFP, QSFP28/QSFP100 for 100G speeds and QSFP+ for 40G speeds

Breaking down the optics required to achieve this can be found in the charts below. The optics below are designated using Arista Product SKUs

Note: Please ensure that the switch being considered for breakout supports the speeds being considered, this information can be found in the switch data sheet and on the switch architecture documents.

10G Breakouts

To achieve 10G lane support, we will need to break out a 40G optic.

Note: Select 40G optics can support 4x10G lanes.

10G Breakouts for Short Distances

(using parallel MMF, aqua cables)

Switch Side Remote Side Distance Supported Cabling Requirements
1 x QSFP-40G-SR4

4 x SFP-10G-SR 

or

4 x SFP-10G-SRL

or

4 x SFP-25G-MR-XSR (10G mode)

  • Up to 100M using OM3
  • Up to 150M using OM4
  • Parallel MMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side
1 x QSFP-40G-XSR4

4 x SFP-10G-SR

or

4 x SFP-25G-MR-XSR (10G mode)

  • Up to 300M using OM3
  • Up to 400M using OM4
  • Parallel MMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side

10G Breakouts for Long Distances

(using parallel SMF, yellow cables)

Switch Side Remote Side Distance Supported Cabling Requirements
1 x QSFP-40G-PLRL4

4 x SFP-10G-LR

or 

4 x SFP-10G-LRL

or

4 x SFP-25G-MR-LR*

(10G mode)

  • Up to 1 KM using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side
1 x QSFP-40G-PLR4

4 x SFP-10G-LR

or

4 x SFP-25G-MR-LR*

(10G mode)

  • Up 10 KM using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side

* Attenuation may be required

25G Breakouts

To achieve 25G lane support, we will need to break out a 100G optic.

Note: Select 100G optics can support 4x25G lanes.

25G Breakout for Short Distances

(using parallel MMF, aqua cables)

Switch Side Remote Side Distance Supported Cabling Requirements

1 x QSFP-100G-SR4

or 

1 x QSFP-100G-XSR4

4 x SFP-25G-SR

or 

4 x SFP-25G-MR-XSR (25G mode)

  • Up to 70M using OM3
  • Up to 100M using OM4
  • Parallel MMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side
1 x QSFP-100G-XSR4 4 x SFP-25G-MR-XSR (25G mode)
  • Up to 200M using OM3
  • Up to 300M using OM4
  • Parallel MMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side

25G Breakouts for Long Distances

(using parallel SMF, yellow cables)

Switch Side Remote Side Distance Supported Cabling Requirements
1 x QSFP-100G-PSM4

4 x SFP-25G-LR

or

4 x SFP-25G-MR-LR

(25G mode)

  • Up to 500M using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side

100G Breakouts

To achieve 100G lane support, we will need to break out a 400G optic.

Note: Select 400G optics can support multiple 100G/200G lanes.

100G Breakouts for Short Distances

Switch Side Remote Side Distance Supported Cabling Requirements

1 x OSFP-400G-SR8

or 

1 x QDD-400G-SR8

2 x QSFP-100G-SR4 

or

2 x QSFP-200G-SR4

  • Up to 100M using MMF
  • Parallel MMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 2 x MTP/MPO connectors for Remote Side

1 x OSFP-400G-DR4

or 

1 x QDD-400G-DR4

4 x QSFP-100G-DR
  • Up to 500M using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side

100G Breakouts for Long Distances 

Switch Side Remote Side Distance Supported Cabling Requirements

1 x OSFP-400G-XDR4

or 

1 x QDD-400G-XDR4

4 x QSFP-100G-FR
  • Up to 2KM using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 4 x LC connectors for Remote Side
1 x OSFP-400G-2FR4

2 x QSFP-100G-CWDM4

  • Up to 2KM using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 2 x LC connectors for Remote Side 

200G Breakouts for Long  Distances

Switch Side Remote Side Distance Supported Cabling Requirements
1 x OSFP-400G-2FR4

2 x QSFP-200G-SR

  • Up to 2KM using SMF
  • Parallel SMF Cabling
  • MTP/MPO connector for QSFP side, Breakout cabling to 2 x MTP/MPO connectors for Remote Side 

Pre-Terminated Breakout cables 

Direct Attached Copper Breakout Cables (DAC) and Active Optical Breakout Cables (AOC) provide a cost effective way to breakout out switch interfaces for short runs or inter-rack/inter-datacenter use cases. The tables below provide a quick overview of the breakout options available. Active Optical Cables (AOC) and Active Direct Attached Copper (Active DACs) are treated as optics/transceivers in Arista switches.

Pre Terminated 10G Breakouts

Arista has few options of pre-terminated breakout lengths to breakout a QSFP interface to 4x10G SFP lanes for short lengths. The are listed as follows:

Cable SKU Notes:
CAB-Q-S-xxM
  • Replace xx with your cable lengths of: 0.5, 1, 2, 3, 5 Metres.  
  • This is a 40G QSFP interface breaking out to 4x10G SFP interfaces

Pre Terminated 25G Breakouts

Arista has few options of pre-terminated breakout lengths to breakout a QSFP, QSFP-DD or OSFP interface to individual 25G lanes for short lengths. The are listed as follows:

Cable SKU Notes:
CAB-Q-4S-100G-xxM
  • Replace xx with available cable lengths of: 1, 2, 3, 5 Metres.  
  • This is a 100G QSFP interface breaking out to 4x25G SFP interfaces
CAB-O-8S-200G-XXM
  • Replace xx with available cable lengths of: 1, 2, 3 Metres. 
  • This is a 200G OSFP interface breaking out to 8x25G SFP interfaces
CAB-D-8S-200G-1M
  • Replace xx with available cable lengths of: 1, 2, 2.5 Metres. 
  • This is a 200G QSFP-DD interface breaking out to 8x25G SFP interfaces

Pre Terminated 50G Breakouts

Arista has few options of pre-terminated breakout lengths to breakout a QSFP, QSFP-DD and OSFP interface to 50G QSFP lanes for short lengths. The are listed as follows:

Cable SKU Notes:
CAB-Q-2Q-100G-xxM
  • Replace xx with available cable lengths of: 1, 2, 3, 5 Metres.  
  • This is a 100G QSFP interface breaking out to 2x50G QSFP interfaces
CAB-D-4Q-200G-xxM
  • Replace xx with available cable lengths of: 1, 2, 2.5 Metres.  
  • This is a 200G QSFP-DD interface breaking out to 4x50G QSFP interfaces
CAB-O-4Q-200G-xxM
  • Replace xx with available cable lengths of: 1, 2, 3 Metres.  
  • This is a 200G OSFP interface breaking out to 4x50G QSFP interfaces

Pre Terminated 100G Breakouts

Arista has few options of pre-terminated breakout lengths to breakout a OSFP or QSFP-DD interface to 100G QSFP lanes for short lengths. The are listed as follows:

Cable SKU Notes:
CAB-O-2Q-200G-xxM
  • Replace xx with available cable lengths of: 1, 2, 3 Metres.  
  • This is a 200G OSFP interface breaking out to 2x100G QSFP interfaces
CAB-D-2Q-200G-xxM
  • Replace xx with available cable lengths of: 1, 2, 2.5 Metres.  
  • This is a 200G QSFP-DD interface breaking out to 2x100G QSFP interfaces
CAB-O-4Q-400G-xxM
  • Replace xx with available cable lengths of: 1, 2, 3 Metres.  
  • This is a 400G OSFP interface breaking out to 4x100G QSFP interfaces
CAB-D-4Q-400G-xxM
  • Replace xx with available cable lengths of: 1, 2, 2.5 Metres.  
  • This is a 400G QSFP-DD interface breaking out to 4x100G QSFP interfaces

Pre Terminated 200G Breakouts

Arista has few options of pre-terminated breakout lengths to breakout a OSFP or QSFP-DD interface to 200G QSFP lanes for short lengths. The are listed as follows:

Cable SKU Notes:
CAB-O-2Q-400G-1M
  • Replace xx with available cable lengths of: 1, 2, 3 Metres.  
  • This is a 400G OSFP interface breaking out to 2x200G QSFP interfaces
CAB-D-2Q-400G-1M
  • Replace xx with available cable lengths of: 1, 2, 2.5 Metres.  
  • This is a 400G QSFP-DD interface breaking out to 2x200G QSFP interfaces

Appendix

For detailed information on breakout cabling and optics can be found in the following Optic FAQ documents below:

https://www.arista.com/assets/data/pdf/40G_FAQ.pdf

https://www.arista.com/assets/data/pdf/Arista100G_TC_QA.pdf

https://www.arista.com/assets/data/pdf/Datasheets/Arista-400G_Optics_FAQ.pdf

Sample Breakout Cable is below for Reference.  These cables can be purchased from your preferred cabling/fiber provider.

Parallel MMF Breakout cable

MMF Breakout Cable

Parallel SMF Breakout Cable 

SMF Breakout Cable

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