XFP & SFP+ 10GbE Optical Modules Overview

srijeda , 20.04.2016.

To accommodate an increasing number of bandwidth-hunger applications and traffic types, an ocean of safe-proof network products have been designed and released into market, including optical modules offered to satisfy the changing and fast-growing bandwidth demands in data centers. The optical modules are devices that connect the cabling to the network, providing interface between the equipment and the cabling, sending and receiving data.

There are various transceiver types available to match each Gigabit standard. For Gigabit technology, there are two defined transceiver types: Gigabit Interface Connector (GBIC), and the “mini-GBIC” or Small Form-factor Pluggable (SFP). For 10 Gigabit Ethernet (GbE) connectivity modules, there are three types: XENPAK (and related X2 and XPAK), XFPSFP+ and SFP+. This text mainly discusses the last two 10GbE optical modules types: XFP and SFP+.

XFP & SFP+ Main Features
Optical modules refer to optical transceivers which consist of a transmitter on one end of a fiber and a receiver on the other end. XFP and SFP+ can be plugged into routers, switches, transport gear, or pretty much any network device to transmit and receive signals. They are hot swappable while the device is operating, standardized to be interchangeable among vendors, capable of operating over many different physical medium and at different distances. Being hot-swappable input/output device, XFP and SFP+ have the following main features in common.

Allow flexibility of interface choice;

Support “pay-as-you-populate” model;

Designed with strong digital optical monitoring capability;

Optical interoperability with 10GBASE XENPAK, and 10GBASE X2 on the same link;

XFP Optical Module

Protocol-independent and hot-pluggable, XFP (10G SFP) is the first small form factor 10GbE optics, typically operating at near-infrared wavelengths of 850nm, 1310nm or 1550nm with LC connector. XFP modules can provide the required optical reach over different fiber optic types (e.g. multi-mode fiber, MMF or single-mode fiber, SMF), commonly available in several categories: SR, LR, ER and ZR.

10GBASE-SR XFP
10GBASE-SR XFP (eg. XFP-10G-MM-SR) is specified to work through MMF using 850nm lasers. This XFP type supports a link length of 26m on standard FDDI-grade MMF. And when using 2000 MHz/km MMF (OM3), 300m link lengths are possible. Fiberstore compatible Cisco XFP-10G-MM-SR is able to realize 300m distance reach over OM3 with the maximum data rate at 10.3125Gbps.

10GBASE-LR XFP
10GBASE-LR XFP is designed to operate via SMF using 1310nm lasers. The maximum link length that XFP 10GBASE-SR port type can support is 10km when it’s used in combination with high-quality optics.

SFP+ Optical Module
As the result of Multi-source Agreements (MSAs) that enable equipment manufacturers to produce 802.3ae-compliant pluggable transceivers, SFP+ modules use the same physical form factor as a Gigabit SFP. It’s the enhanced version of SFP. Nowadays, SFP+ has become a popular industry format supported by many network component vendors for 10GE systems. Similar to XFP, SFP+ also has different port types, like SR, LX4, LR, and so on.


10GBASE-SR SFP+
10GBase-SR is the original multi-mode optics specification, and is still by far the most commonly used. Since it uses a single, low cost solid state laser assembly, 10GBase-SR is the least expensive of the optical modules available for a 10GbE SFP+ platform. Just like 10GBASE-SR XFP, 10GBase-SR SFP+ is very sensitive to fiber type. When using standard MMF, the possible link length supported by 10GBASE-SR SFP+ is 26m, and when deploying OM3 or 10GbE-optimized fiber, the maximum link length is 300m.

10GBASE-LX4 SFP+
To break through the distance limitations of 10GBASE-SR optics, the 10GBASE-LX4 standard was developed later. LX4 uses 4 lasers, each operating at a different wavelength at a 2.5Gbps data rate, resulting in a range of 240-300m link length which depends on cable grade. However, due to the complex laser assembly, it is not possible to get LX4 optics in SFP+ versions. With the ready availability of OM3 fiber and newer standards that provide long reach over multi-mode with a single laser, LX4 has become obsolete nowadays.

10GBASE-LR SFP+
10GBASE-LR is a port type for SMF, supporting the maximum link length of 10km. During data transmission, a single laser operating at 1310nm is used, which allows LRM optics to be packaged in XFP and SFP+ form factors.

Conclusion
I detail the information about two 10GbE optical module types—XFP and SFP+ with the hope that you when you go on the task of one of the most confusing aspects—choosing and deploying 10Gig fiber switches. Fiberstore supplies various types of 10GbE optical modules, including SFP+ and XFP (XFP-10G-MM-SR mentioned above). Besides, other Gigabit standard modules are also available in Fiberstore, such as 1000BASE SFP transceivers (eg. Juniper EX-SFP-1GE-LX). If you want to buy such an optical module for your network connectivity, you can visit Fiberstore for your reference.

Oznake: 10GbE, Cisco XFP-10G-MM-SR, SFP, Gigabit standard module, EX-SFP-1GE-LX

Why Choose 10 Gigabit Ethernet?

srijeda , 13.04.2016.

Since Ethernet technology came into people's use in 1970s, Gigabit Ethernet (GbE) has long deminated the local area network (LAN) applications. But when to connect servers to storage area networks (SANs) and network attached storage (NAS) or for server-to-server connections, GbE seems to be not sufficient enough. In such a case, Ethernet has developed the later technology standard as newer, higher performing iteration—10GbE.

The Institute of Electrical and Electronics Engineers (IEEE) 802.3 working group has published several standards regarding 10GbE, including 802.3ae-2002 (fiber -SR, -LR, -ER), 802.3ak-2004 (CX4 copper twin-ax InfiniBand type cable), etc. Among these standard interfaces, 10GBASE-SR is the most-widely used type, like Cisco SFP-10G-SR and Cisco SFP-10G-SR-S. With 10Gigabit connectivity becoming widely available, 10GbE technology has emerged as the connection choice for many companies to grow their networks and support new applications and traffic types. Behind the 10GbE, there are three main advantages which explain why users choose it today.

Data Center Network Simplification
While Fibre Channel and InfiniBand are specialized technologies that can connect servers and storage, they can’t extend beyond the data center. However, a single 10GbE network and a single switch can support the LAN, server-to-server communications, and can connect to the wide-area network. Ethernet and IP network technology are familiar to network designers, so replacing multiple networks with a single 10GbE network avoids complex staff training. And by consolidating multiple gigabit ports into a single 10gigabit connection, 10GbE simplifies the network infrastructure while providing greater bandwidth.

Traffic Prioritization and Control
A major advantage of 10GbE is that separate networks for SANs, server-to-server communication and the LAN can be replaced with a single 10GbE network. While 10Gb links may have sufficient bandwidth to carry all three types of data, bursts of traffic can overwhelm a switch or endpoint.

SAN performance is extremely sensitive to delay. Slowing down access to storage has an impact on server and application performance. Server-to-server traffic also suffers from delays, while LAN traffic is less sensitive. There must be a mechanism to allocate priority to critical traffic while lower-priority data waits until the link is available.

Existing Ethernet protocols do not provide the controls needed. A receiving node can send an 802.3x PAUSE command to stop the flow of packets, but PAUSE stops all packets. 802.1p was developed in the 1990s to provide a method to classify packets into one of eight priority levels. However, it did not include a mechanism to pause individual levels. The IEEE is now developing 802.1Qbb Priority-based Flow Control (PFC) to provide a way to stop the flow of low-priority packets while permitting high-priority data to flow.

A bandwidth allocation mechanism is also required. 802.1Qaz Enhanced Transmission Selection (ETS) provides a way to group one or more 802.1p priorities into a priority group. All of the priority levels within a group should require the same level of service. Each priority group is then assigned a percentage allocation of the link. One special priority group is never limited and can override all other allocations and consume the entire bandwidth of the link. During periods when high-priority groups are not using their allocated bandwidth, lower-priority groups are allowed to use the available bandwidth.

Congestion control
802.1Qbb and 802.1Qaz by themselves don't solve the packet loss problem. They can pause low-priority traffic on a link, but they don't prevent congestion when a switch or an end node is being overwhelmed by high-priority packets from two or more links. There must be a way for receiving nodes to notify sending nodes to slow their rate of transmission.

IEEE 802.1Qau provides such a mechanism. When a receiving node detects that it is nearing the point where it will begin discarding incoming packets, it sends a message to all nodes currently sending to it. Sending nodes slow their transmission rate. Then, when congestion is cleared, the node sends a message informing senders to resume their full rate.

10GbE in Data Centers
For many institutions, especially those that utilize automated trading, uptime and response time is critical. Longer delays than a second can be exceedingly costly. With servers now being able to transmit bandwidth and network downtime, today’s data centers of some companies need extended bandwidth. 10GbE is an ideal technology to move large amounts of data quickly. The bandwidth it provides in conjunction with server consolidation is highly advantageous for Web caching, real-time application response, parallel processing and storage.

Conclusion
10GbE comes as the ideal connection choice for some companies, delivering greater bandwidth for sending data over Ethernet architectures with reduced cost and complexity. Fiberstore offers an ocean of 10GbE solutions, such as high-quality SFP+ modules (eg. Cisco SFP-10G-SR and SFP-10G-SR-S mentioned above). For more information about 10GbE equipment, you can visit Fiberstore or directly connect me at Linkedin @Fern Xu (Fiberstore).

Oznake: 10GbE, 10GBASE SR, Cisco SFP-10G-SR, Cisco SFP-10G-SR-S, SFP+ modules