FAQ: Optics and cables

FAQ: Optics and cables


Technical Information

Platform Support Information

Services Information

Open Networking Information

SAS Connectivity

Technical Information



Q. What are the different types of cables?

 Different types of cables
Figure 1:
Different types of cables

Q. What is a lane?

Lanes are used to achieve higher data transmission rates such as 40GbE and 100Gb. Multiple lower rate data streams (10GbE or 25GbE) are grouped in lanes. For 40GbE there are four lanes carrying 10Gb in each direction and for 100GbE there are four lanes carrying 25Gb or ten lanes carrying 10Gb. The lanes can be copper cables, wavelengths, or fibers.

Q. Can existing 10GbE fiber cables be used for 40GbE?

There is no separate category for 10GbE, 25GbE, 40GbE, 50GbE, or 100GbE fiber cables. All fiber cables, either SMF or MMF, can be used for any speed as long as the connector has the right fit and the fiber type meets the optic wavelength specifications.

Q. Are DWDM and CWDM optics just like a regular optic?

Users of DWDM optical modules are expected to engineer the link to suit their deployment. Choice of appropriate DWDM mux-demux, optical amplification, CD compensation, etc. to meet specific link budget requirements is left to the end user. Both ends of the link must have Dell DWDM optics. Dell can provide detailed optical transceiver data-sheet upon request.

Users of CWDM optical modules can simply connect the two optics using a single mode fiber (SMF) cable just like a regular Ethernet optic is connected. It is not absolutely required to use Dell CWDM optics on both ends.

Q. What is the difference between MPO and MTP connector?

MPO is the acronym for "Muti-fiber Push On" connector generally used to connect fiber optic inter-connecting devices and passive components.
MTP is the acronym for "Multi-fiber Termination Push on" connector which is a high performance MPO connector with multiple engineered product enhancements to improve optical and mechanical performance when compared to generic MPO connectors.

The MTP connector is in complete compliance with all MPO connector standards and is also inter-matable with all generic MPO-style connectors that are compliant to these industry standards.

Q. What does the alpha-numeric interconnect description (SX, LX, SR, LR, SR4, LR4, etc.) mean for optics?

The alpha-numeric interconnect description conveys information such as the maximum distance supported between the optics, the type of media that can be used to connect the two optics, etc. Following tables provide some information to better understand this interconnect information.

1Gb Ethernet
Interconnect Description Medium Range
SX Short Reach MMF < 500m
LX Long Reach SMF < 10km
FX Fast Ethernet MMF < 2km
ZX SMF < 80km
T Twisted Pair Cat 5/6 < 100m

Table 1: 1Gb Ethernet

10Gb Ethernet
Interconnect Description Medium Range
USR Ultra Short Reach MMF < 100m
SR Short Reach MMF < 300m
LR Long Reach SMF < 10km
LRM Long Reach Multi-mode SMF < 220m
ER Extended Reach SMF < 40km
ZR SMF < 80km
DWDM Dense Wavelength Division Multiplexing SMF < 40km
T-DWDM Tunable Dense Wavelength Division Multiplexing SMF < 80km
Table 2: 10Gb Ethernet

40Gb Ethernet
Interconnect Description Medium Range
SR4 Short Range MMF < 150m
ESR4 Extended Range MMF < 400m
LR4 Long Range SMF < 10km
PSM4-Pigtail Parallel Single Mode Pigtail SMF < 10km
PSM4-LR Parallel Single Mode SMF < 10km
LM4 Long Reach Multi-mode

MMF

SMF

< 160m

< 1km

QSA QSFP to SFP Adapter depends of installed transceiver depends of installed transceiver
Table 3: 40Gb Ethernet

100Gb Ethernet
Interconnect Description Medium Range
SR4 Short Range MMF < 100m
LR4 Long Range SMF < 10km
LR4-LITE Long Range - Lite SMF < 2km
PSM4 Parallel Single Mode SMF < 2km
PSM4-IR Parallel Single Mode - Intermediate Range SMF < 500m
CWDM4 Coarse Wavelength Division Multiplexing SMF < 2km
SR10 Short Range MMF < 150m
Table 4: 100Gb Ethernet

Q. How does the QSFP to SFP breakout cable convert one 40GbE link into four 10GbE links?

The breakout cables leverage parallel technology standard defined by IEEE. This technology uses 4 lanes in each direction that must be supported by the switch or router. A fiber, which is a passive medium and has no concept of the signal speed, connects one 40GbE port (carrying four 10GbE lanes) to four 10GbE ports.

Q. What are TwinAx, TwinX, Direct Attach Copper, and DAC cables?

TwinAx, TwinX, Direct Attach Copper, and DAC cables all refer to the same cable that uses copper, instead of fiber optics, medium to transport the signals.

Q. Can SR optics be connected to LR optics? If so, what type of cable should be used?

SR and LR optics cannot be connected because of the modal differences. Both SR and LR have similar receive (Rx) power as well as launch Tx power specifications. If someone accidentally connects SR optic to LR optic then no critical damage is expected based on the SR and LR specifications.

Q. Will a Single Mode Fiber (SMF) cable work with an optic requiring Multi-mode Fiber (MMF) cables or vice-versa?

The answer is maybe. In some cases it may be possible to use SMF cables with an optic requiring MMF cables but the reverse is never possible. SMF connectors and cables are made to tighter tolerances so the ferrule hole may be too small for some MMF cables. MMF connectors have bigger holes for the fiber and will have high loss (>1dB) with SMF. Also MMF connectors may not be PC (physical contact) polish which is terrible for return loss. MMF cables may not fit the smaller hole in SMF connectors.



Platform Support Information



Q. What kind of optics and cables are available through Dell Networking?

Dell Networking offers a comprehensive optics and cables portfolio for Ethernet and Fibre Channel connectivity.

Ethernet
  • Optics: 1GbE, 10GbE, 40GbE, and 100GbE optics
  • Active Optical Cables (AOC): 10GbE, 40GbE, and 100GbE
  • Active Optical Cables (AOC) - Breakout: 40GbE to 4x10GbE
  • Direct Attached Cables (DAC): 10GbE, 40GbE, and 100GbE
  • Direct Attached Cables (DOC) - Breakout: 40GbE to 4x10GbE, 100GbE to 4x25GbE
  • MTP/MPO cables
Fibre Channel
  • Optics: 8Gb and 16Gb

Additional details can be found in the Dell Optics and Cables Connectivity Guide.

Q. What are the wavelengths supported by different optics?

Please check Dell Optics and Cables Connectivity Guide for wave length information specific to the optics you are considering.

Q. How can one find the maximum distance supported by optics?

Please check Dell Optics and Cables Connectivity Guide for maximum distance supported by optics you are considering.

Q. Is it ok to install a non-Dell optic in a Dell switch?

A customer is generally discouraged from installing non-Dell optics in Dell switches.

In order to ensure that users enjoy the most reliable network experience with Dell switches, Dell goes through a very stringent and lengthy process of optics validation, qualification, and certification. Dell fully stands behind such a solution and, in the unlikely event that a user comes across a problem, Dell’s support personnel will help address the issues.

If a non-Dell optic is plugged into a Dell switch, the switch may continue to perform as well as the optic allows. Please contact your Dell representative for more specific information.

Q. Is it ok to install a non-Dell DAC cable in a Dell switch?

In order to ensure that users enjoy the most reliable network experience with Dell switches, Dell goes through a very stringent and lengthy process of cables validation, qualification, and certification. Dell fully stands behind such a solution and, in the unlikely event that a user comes across a problem, Dell’s support personnel will help address the issues.

If a non-Dell DAC cable, which is standards compliant, is plugged into a Dell switch, the switch will continue to perform as well as the cable allows. Additionally, since cables are passive components and as long as the cables are standards based, If Dell Support determines that the reported issue is caused by the use of non-Dell DAC then they will recommend that the customer replace the unsupported DAC with qualified Dell optics.

As a matter of best practice, Dell recommends that end user test non-Dell optics appropriately, prior to deploying them in production environment.

Q. Is it ok to install an optic from a Dell switch into Dell server NICs?

It is very common for customers to use DAC (TwinAx) cables instead of optics to connect server NICs to switches. Customers have the flexibility to use either a switch qualified or a server qualified DAC cable.

If a customer chooses to use optics, Dell recommends using a switch qualified optic in a switch and a NIC qualified optic in a server NIC. Fibre Channel (FC) HBAs and FC switches ship with pre-installed FC optics. Customer should use the same optics in both of these products.

Please consult your Dell representative to find a list of qualified optics.

Q. Is it ok to install an optic from a Dell switch into Dell storage?

It is very common for customers to use DAC (TwinAx) cables instead of optics to connect Dell Ethernet based storage ports to switches. Customers have the flexibility to use either a switch qualified or a storage qualified DAC cable.

If a customer chooses to use optics, Dell strongly recommends using a storage qualified optic in a storage controller port and a switch qualified optic in a switch port. Fibre Channel (FC) storage and FC switches ship with pre-installed FC optics. Customer should use the same optics in both of these products.

Please consult your Dell representative to find a list of qualified optics.

Q. Is it ok to install an optic from one Dell switch into another Dell switch?

In most cases, the answer is yes. However, it is highly encouraged that the user contact their Dell representative to confirm if there are any specific requirements or exceptions.

Dell supplied Fibre Channel (FC) optics must be installed in Dell’s FC products. Dell supplied FC optics for Brocade OEM products must be used with Brocade products. Dell FC optics in Brocade switches and Brocade optics in Dell switches are not supported.

Q. Is it ok to install an optic from Dell into a non-Dell switch?

All Dell optics go through a very strict qualification process which ensures that the customers' environments enjoy the best possible up-time. Customers looking for optics for their mission critical IT applications can certainly trust Dell branded optics. However, some equipment vendors may have specific qualification requirements for optics. Dell encourages customers to check the optics support policy of the equipment vendor to ensure a better experience.

Q. Is it ok to use a Dell DAC cable to connect a Dell device to a non-Dell device?

Dell DAC should function normally when inter-connecting Dell and non-Dell Devices. However, Dell recommends use of optics in multivendor environment because there is always a possibility that a non-Dell device may have deviated from the standards based implementation.

Dell Support will assist the customer in case of a problem. However, if Dell Support identifies that the reported issue is caused by use of DAC cables, they will likely recommend the use of optics, instead of DAC.

As a matter of best practice, Dell recommends that the end user test DAC cables, prior to deploying them in multi-vendor inter-connect environment.

Q. Is it ok to use a Dell DAC cable to connect Dell switch to other Dell devices?

Dell provides full and complete support for Dell DAC, when deployed between Dell devices. Any issues attributed to the use of Dell DAC on ,and, between Dell devices, will be investigated by Dell Support

Q. Is it ok to use a DAC cable between a 10bE CNA and a 1GbE switch or 1GbE adapter with 10GbE switch?

It is recommended to use optics instead of DAC if connecting at 1GbE speeds. Additionally, please ensure that both the switch and the server adapter support operation at 1GbE because some adapters support 10GbE only.

Q. What optics are supported in Dell QSA transceiver?

Following is the list of Dell optics that are supported in the QSA transceiver.

1GbE SFP
  • SX
  • LX
  • 1000BT

10GbE SFP+
  • SR
  • LR
  • ER
  • ZR


Services Information



Q. Are Dell optics covered under Dell warranty and support options?

Dell approved optics are covered by Dell warranty and support options but there are limitations and different terms based on the type of warranty. Please find more detail here: http://www.dell.com/learn/us/en/19/campaigns/lifetime-warranty. Typically, the warranty support on the Dell approved optic aligns with the hardware warranty.

Q. Are Dell optics covered under the Lifetime Limited Warranty (LLW) for N series products?

Dell approved optics are covered as long as the original customer owns the product.

Q. Are Dell approved optics covered under ProSupport, ProSupport Plus and ProSupport Flex for Data Center?

The Dell approved optics are covered under the same terms and conditions as the ProSupport contract. For example, if a customer purchases a 3 year NBD ProSupport contract then that Dell approved optic will also be covered NBD for 3 years.


Open Networking (ON) Information



Q. Does Cumulus OS lock specific optics on Dell Networking switches?

Cumulus Linux does not preclude the use of any industry-standard transceiver or direct-attached cabling.

Q. What optics are supported by Cumulus OS on Dell Networking?

Cumulus does not provide a list of supported optics and cables. A list of industry-standard transceivers and cables, sorted by type, with the necessary compliance requirements that have shown to work well in systems running Cumulus Linux is available as a guidance. These examples, along with the sample part number, link to the vendor's website, and should provide enough information to source products from your favorite transceiver or cable vendor.

Q. Are third party optics supported on Dell Open Networking (ON) switches?

Third party optics may be supported by the vendor providing OS for Dell Open Networking switches. Please check with your account representative for more specific information.

Q. Are all Dell optics supported on Dell Open Networking (ON) switches?

Generally, all applicable Dell optics are supported on the Dell Open Networking switches with 3rd party OS. There may be some exceptions to this due to technical, qualification, positioning or other such reasons. Please check with your account representative for more specific information.

SAS Connectivity



Q. What is SAS connectivity?

SAS (Serial-attached SCSI) is a method used in accessing computer peripheral devices that employs a serial means of digital data transfer over thin cables. The method is specified in the American National Standard Institute (ANSI) standard also known as ANSI/INCITS 376-2003. In the business enterprise, serial-attached SCSI is especially of interest for access to mass storage devices, particularly external hard drives and magnetic tape drives.

Q. What kind of data transfer rates are supported on SAS?

Tooday, 12Gb is the maximum data transfer rate which supported by SAS 3.0. SAS 2.0, which is also widely being used today supports up to 6Gb of data transfer rates.

Q. What type of SAS cables are available for the SCv2020 and SC4020?

Both SCv2020 and SC4020 support 6Gb to 6Gb on the back-end. SCv2020 supports 12Gb to 12Gb on the front-end.

Q. What is the different between 6Gb and 12Gb SAS cables?

Yes, mini SAS to mini SAS cables are used for 6Gb data rate (SAS 2.0) and mini SAS HD to mini SAS HD cables are used for 12Gb data rate (SAS 3.0).

Q. What is the maximum length of cables supported by Dell Storage?

Currently, Dell supports 0.6m, 2m, and 4m cables lengths for SAS.

Q. What is the maximum number of devices supported on each SAS interface?

The maximum number of devices supported on each SAS interface depends on RBOD (RAID Bunch Of Disks) and EBOD (Extended Bunch Of Disks) connection types. Please consult with your storage representative for product specific information.

Q. What is a SAS switch?

A SAS switch is a special device that extends that capabilities of SAS in Direct Attached Storage (DAS) environments by allowing multiple servers to connect to one or more independent external storage systems.

Q. Does Dell Storage support SAS switch?

Today, Dell storage has not qualified any SAS switches with Dell storage. Please consult your Dell representative for more current information.




Article ID: SLN312465

Last Date Modified: 08/14/2018 01:40 AM


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