1000BASE-What?

There are many kinds of optical transceiver in the market. When looking at a transceiver module, you may see words like 1000BASE-CX, 1000BASE-SX, 1000BASE-T, and so on. For example, the following picture shows a 3CSFP91 compatible SFP transceiver. You can see "1000BASE-SX SFP" on it. What do they mean? And what's the difference between 1000BASE-SX, 1000BASE-CX, and 1000BASE-T? In this post, a brief introduction to 1000BASE will be given.

What Does 1000BASE Mean?

The "1000" refers to the transmission speed of 1000Mbps. In computer networking, Gigabit Ethernet (GE or 1GbE) is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second, as defined by the IEEE 802.3-2008 standard. The cables and equipment are very similar to previous standards and have been very common and economical since 2010. You may wonder what the word "BASE" means. BASE refers to "baseband", meaning that this is an unfiltered line not requiring a digital modulation scheme. Back in the day, there was a 10PASS-TS version of Ethernet that used a signaling scheme similar to a modem, but baseband is dominant today. So 1000BASE refers to a Gigabit Ethernet connection that uses the unfiltered cable for transmission.

1000BASE-What?

The next part is the cabling used to carry the signals. The earliest forms of Ethernet used coaxial cable, but thin twisted-pair cabling became popular in the mid-1990s. Faster versions of Ethernet also often use fiber optics rather than electrical signals. There are a bewildering assortment of physical interconnects for Ethernet. But the naming system isn't as complex as it might appear. The first letter tells us which kind of wire we are talking about:

• "S" means short-range multi-mode optical cable (less than 100 m)
• "L" means long-range single- or multi-mode optical cable (100 m to 10 km)
• "E" means extended-range optical cable (10 km to 40 km)
• "Z" means long-range single-mode cable at a higher wavelength
• "T" means twisted-pair cable (e.g. the common Category 5 in use today)
• "K" means a copper backplane
• "C" means balanced copper cable
• "B" uses two wavelengths over a single optical cable

Next is the coding scheme for data on the wire: "X" means 8B/10B block coding for Gigabit Ethernet. Then, we have a number representing the number of parallel "lanes" for data: "1" would mean serial (non-parallel) but is omitted instead; "4" or "10" are available for copper wire; just about any other number could be used for optical lanes or wavelengths. As you can see, common unshielded twisted pair wiring is "BASE-T", optics are denoted according to their range ("S", "L", "E"), and backplanes use "K" copper.

Examples

1000BASE-SX standard is a variant coupled to a VCSEL laser with a short wavelength of 850nm. It has a maximum length of 550 meters. 1000BASE-SX technologies are being widely implemented in enterprise-level networks and primarily used between pieces of equipment within a building. 1000BASE-LX standard has a working distance of up to 5 km over single-mode optic fiber. And it can also be used to transmit data over common multi-mode fiber options with a maximum length of 550m. 1000BASE-EX standard is capable of transmitting up to 40 km over a single-mode optic fiber pair due to higher quality optics. 1000BASE-CX is an initial standard for Gigabit Ethernet connections with maximum distances of 25 meters using balanced shielded twisted pair. 1000BASE-KX standard is for Ethernet operation over electrical backplanes. It defines one to four lanes of backplane links, one RX and one TX differential pair per lane. The 1000BASE-KX variant uses 1.25GBd electrical (not optical) signalling speed. 1000BASE-T normally uses four pairs of the commonly installed Category 5 unshielded twisted pair (UTP) cable or enhanced category 5 cabling version of UTP cabling to achieve gigabit data rates. The image below shows a Moxa SFP-1GLSXLC 1000BASE-LX SFP transceiver.

There are various 1000BASE SFP transceivers available depending on the your application and distance capability required. Fiberstore is a professional manufacturer and supplier, offering various kinds of 1000BASE SFP transceivers 100% compatible with major brands like Cisco, HP, Juniper, Force10, D-link, 3Com. They are backed by a lifetime warranty, and we also can customize optical transceivers to fit your specific requirements.

1000BASE-T Gigabit Ethernet over Category 5 Cable

Various copper and fiber choices are available on the market today. When deciding a cabling system, network managers should know how to choose the most appropriate cabling system for their network infrastructure in the long run. Many of the cabling installed today inside buildings is Category 5. Many factors, like punch down blocks, and patch panel connections, affect the performance of 1000BASE-T technology if not correctly implemented. This article gives an introduction to 1000BASE-T Gigabit Ethernet operation over the installed base of Category 5 cabling.

1000BASE-T and Category 5 Cabling

1000BASE-T is a type of gigabit Ethernet networking technology that uses copper cables as a medium. 1000BASE-T uses four pairs of Category 5 unshielded twisted pair cables to achieve gigabit data rates. There should be no need to replace existing Category 5 cabling to use 1000BASE-T. The standard is designated as IEEE 802.3ab and allows 1Gbps data transfers for distances of up to 330 feet. 1000Base-T came into wide use in 1999, gradually replacing fast Ethernet for wired local networks simply because it was 10 times as fast. Equipment and cables are very similar to previous Ethernet standards and by 2011 were very common and economical. These were the biggest factors that ensured this standard's wide acceptance. The 1000BASE-T product is designed to operate over Category 5 cabling. The image below shows how 1000BASE-T works.

Gigabit Bandwidth over Category 5 Cabling

1000BASE-T uses a symbol rate of 125 Mbaud (A 125 Mbaud symbol rate is required because 100BASE-TX uses 4B/5B coding), but it uses all four pairs for the link and a more sophisticated five-level coding scheme. In addition, 1000BASE-T sends and receives simultaneously on each pair. Combining 5-level coding and 4 pairs allows 1000BASE-T to send one byte in parallel at each signal pulse. 4 pairs 125 Msymbols/second X 2 bits/symbol = 1Gbps.

Problems During Cable Installation

Of course, it isn't quite this simple. In addition to moving the symbols across the link, 1000BASE-T must also deal with the effects of return loss and crosstalk, and other factors.

Return loss measures the amount of reflected signal energy resulting from impedance changes in the cabling link. If too much energy is reflected back onto the receiver, the device does not perform optimally. Factors that affect the return loss are:

• The number of transition points, as there is a connection through an RJ-45 to another connector, a patch panel, or device at each transition point.
• Removing the jacket that surrounds the four pairs of twisted cable. When RJ-45 connections are made, this is minimized to 1 1/4 inch (32 mm).
• Untwisting any pair of the twisted-pair cabling. It is important that any untwisting be minimized to 3/8 inch (10 mm) for RJ-45 connections.
• Cabling or bundling of multiple Category 5 cables. If not correctly implemented, this can adversely affect all cabling settings.

Crosstalk is unwanted signals coupled between adjacent wire pairs. Since 1000BASE-T uses all four wire pairs, each pair is affected by crosstalk from the adjacent three pairs. Near-end crosstalk (NEXT) is crosstalk that appears at the output of a wire pair at the transmitter (near) end of the cable. Far-end crosstalk (FEXT) is a measure of the unwanted signal coupling from a transmitter at the near-end into a neighboring pair measured at the far-end. Crosstalk is characterized in reference to the transmitter.

Conclusion

For optimum performance of your 1000BASE-T product, it is important to fully qualify your cable installation and ensure that it meets or exceeds Category 5 specifications. Fiberstore provides various Category 5 cables and 1000BASE-T optical transceivers for your applications. For example, Finisar FCLF-8520-3 1000BASE-T copper SFP RJ-45 transceiver, and Cisco GLC-T 1000BASE-T SFP copper RJ-45 transceiver, are compliant with the Gigabit Ethernet and 1000BASE-T standards as specified in IEEE 802.3 and 802.3ab. These SFP transceivers link your switches and routers to the network. They are 100% functionally tested, and compatibility is guaranteed.

What Are the Differences of SFP, SFP+, XFP?

SFP, SFP+, and XFP are all terms for a type of transceiver that plugs into a special port on a switch or other network device to convert the port to a copper or fiber interface. These compact transceivers replace the older, bulkier GBIC interface. All these three compact transceivers are hot-swappable and commonly used. It's easy to change interfaces on the fly for upgrades and maintenance without shutting down a switch to swap out a module. These modules are good solutions in having a great quality signal delivered. Which kind of module should you choose? Your choice needs to be based on your understanding of what they are and how they differ from each other.

What Are SFP, SFP+ and XFP?

SFP: SFP stands for small form-factor pluggable. SFP transceiver is a compact, hot-pluggable transceiver used for both telecommunication and data communications applications. The form factor and electrical interface are specified by a multi-source agreement (MSA). These modules can link equipment like routers and switches. SFP transceivers are designed to support SONET, gigabit Ethernet, Fibre Channel, and other communications standards. For every type of SFP transceiver, it works with different wavelengths at a designated location or distance. SX SFP uses 850nm for a maximum of 550 meters, LX SFP use 1310nm for a maximum 10km, ZX SFP could reach 80km. Copper SFP uses a RJ45 interface. It is a popular industry format jointly developed and supported by many network component vendors.

SFP+: SFP+ is an enhanced version of the SFP. The SFP+ specification was first published on May 9, 2006. SFP+ supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and optical transport network standard OTU2. It is a popular industry format supported by many network component vendors. Although the SFP+ standard does not include mention of 16G Fibre Channel it can be used at this speed.

XFP: XFP stands for 10 Gigabit small form factor pluggable. XFP modules are hot-swappable and protocol-independent. With XFP you will surely experience a fast transmission of data in your computer network including your telecommunication links. They typically operate at near-infrared wavelengths (colors) of 850 nm, 1310 nm or 1550 nm. Principal applications include 10 Gigabit Ethernet, 10 Gbit/s Fibre Channel, synchronous optical networking (SONET) at OC-192 rates, synchronous optical networking STM-64, 10Gbit/s optical transport network OTU-2, and parallel optics links. They can operate over a single wavelength or use dense wavelength-division multiplexing techniques.

What Are the Differences?

SFP+ vs SFP

The main difference between SFP and SFP+ is that the SFP+ is used in Gigabit Ethernet applications while SFP is for 100BASE or 1000BASE applications. SFP+ transceivers use the same dimensions of pluggable transceivers in the 10Gbs Ethernet and 8.5Gbs fiber channel with SFP and SFP comply with standards of IEEE802.3 and SFF-8472.

XFP vs SFP+

Generally speaking, both of them are 10G fiber optical modules and can connect with other type of 10G modules. In comparison to earlier XFP modules, SFP+ modules leave more circuitry to be implemented on the host board instead of inside the module. The size of SFP+ is smaller than XFP, thus it moves some functions to motherboard, including signal modulation function, MAC, CDR and EDC. XFP is based on the standard of XFP MSA while SFP+ is compliance with the protocol of IEEE 802.3ae, SFF-8431, SFF-8432.

Fiberstore is a professional manufacturer and supplier for optical fiber products and provides various kinds of SFP, SFP+ and XFP transceivers branded by many famous companies, like Cisco, HP, and Finisar. For example, Cisco XFP-10G-MM-SR, XFP-10GLR-OC192SR, XFP-10GER-192IR+ XFP transceivers, and HP JD118B, JD119B, J9142B SFP transceivers offered by Fiberstore are the most cost-effective standards-based transceiver modules and fully compatible with major brands and backed by a lifetime warranty.