TEN GB ETHERNET
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TEN GB ETHERNET.doc (Size: 441 KB / Downloads: 152)
From its origin more than 25 years ago, Ethernet has evolved to meet the increasing demands of packet-switched networks. Due to its proven low implementation cost, its known reliability, and relative simplicity of installation and maintenance, its popularity has grown to the point that today nearly all traffic on the Internet originates or ends with an Ethernet connection. Further, as the demand for ever-faster network speeds has grown, Ethernet has been adapted to handle these higher speeds and the concomitant surges in volume demand that accompany them.
The One Gigabit Ethernet standard is already being deployed in large numbers in both corporate and public data networks, and has begun to move Ethernet from the realm of the local area network out to encompass the metro area network. Meanwhile, an even faster 10 Gigabit Ethernet standard is nearing completion. This latest standard is being driven not only by the increase in normal data traffic but also by the proliferation of new, bandwidth-intensive applications.
The draft standard for 10 Gigabit Ethernet is significantly different in some respects from earlier Ethernet standards, primarily in that it will only function over optical fiber, and only operate in full-duplex mode, meaning that collision detection protocols are unnecessary. Ethernet can now step up to 10 gigabits per second, however, it remains Ethernet, including the packet format, and the current capabilities are easily transferable to the new draft standard.
In addition, 10 Gigabit Ethernet does not obsolete current investments in network infrastructure. The task force heading the standards effort has taken steps to ensure that 10 Gigabit Ethernet is interoperable with other networking technologies such as SONET. The standard enables Ethernet packets to travel across SONET links with very little inefficiency.
Ethernetâ„¢s expansion for use in metro area networks can now be expanded yet again onto wide area networks, both in concert with SONET and also end-to-end Ethernet. With the current balance of network traffic today heavily favoring packet-switched data over voice, it is expected that the new 10 Gigabit Ethernet standard will help to create a convergence between networks designed primarily for voice, and the new data centric networks.
10 GIGABIT ETHERNET TECHNOLOGY OVERVIEW
The 10 Gigabit Ethernet Alliance (10GEA) was established in order to promote standards-based 10 Gigabit Ethernet technology and to encourage the use and implementation of 10 Gigabit Ethernet as a key networking technology for connecting various computing, data and telecommunications devices. The charter of the 10 Gigabit Ethernet Alliance includes:
Â¢ Supporting the 10 Gigabit Ethernet standards effort conducted in the IEEE 802.3 working group
Â¢ Contributing resources to facilitate convergence and consensus on technical specifications
Â¢ Promoting industry awareness, acceptance, and advancement of the 10 Gigabit Ethernet standard
Â¢ Accelerating the adoption and usage of 10 Gigabit Ethernet products and services
Â¢ Providing resources to establish and demonstrate multi-vendor interoperability and generally encourage and promote interoperability and interoperability events
Â¢ Fostering communications between suppliers and users of 10 Gigabit Ethernet technology and products
THE 10 GIGABIT ETHERNET ALLIANCE
The purpose of the 10 Gigabit Ethernet proposed standard is to extend the 802.3 protocols to an operating speed of 10 Gbps and to expand the Ethernet application space to include WAN links. This will provide for a significant increase in bandwidth while maintaining maximum compatibility with the installed base of 802.3 interfaces, previous investment in research and development, and principles of network operation and management.
In order to be adopted as a standard, the IEEEâ„¢s 802.3ae Task Force has established five criteria that the new 10 Gigabit Ethernet P (proposed) standard must meet:
Â¢ It must have broad market potential, supporting a broad set of applications, with multiple vendors supporting it, and multiple classes of customers.
Â¢ It must be compatible with other existing 802.3 protocol standards, as well as with both Open Systems Interconnection (OSI) and Simple Network Management Protocol (SNMP) management specifications.
Â¢ It must be substantially different from other 802.3 standards, making it a unique solution for a problem rather than an alternative solution.
Â¢ It must have demonstrated technical feasibility prior to final ratification.
Â¢ It must be economically feasible for customers to deploy, providing reasonable cost, including all installation and management costs, for the expected performance increase.
THE 10 GIGABIT ETHERNET STANDARD
Under the International Standards Organizationâ„¢s Open Systems Interconnection (OSI) model, Ethernet is fundamentally a Layer 2 protocol. 10 Gigabit Ethernet uses the IEEE 802.3 Ethernet Media Access Control (MAC) protocol, the IEEE 802.3 Ethernet frame format, and the minimum and maximum IEEE 802.3 frame size.
Just as 1000BASE-X and 1000BASE-T (Gigabit Ethernet) remained true to the Ethernet model, 10 Gigabit Ethernet continues the natural evolution of Ethernet in speed and distance. Since it is a full-duplex only and fiber-only technology, it does not need the carrier-sensing multiple-access with collision detection (CSMA/CD) protocol that defines slower, half-duplex Ethernet technologies. In every other respect, 10 Gigabit Ethernet remains true to the original Ethernet model.
An Ethernet PHYsical layer device (PHY), which corresponds to Layer 1 of the OSI model, connects the media (optical or copper) to the MAC layer, which corresponds to OSI Layer 2. Ethernet architecture further divides the PHY (Layer 1) into a Physical Media Dependent (PMD) and a Physical Coding Sublayer (PCS). Optical transceivers, for example, are PMDs. The PCS is made up of coding (e.g., 64/66b) and a serializer or multiplexing functions.
The 802.3ae specification defines two PHY types: the LAN PHY and the WAN PHY (discussed below). The WAN PHY has an extended feature set added onto the functions of a LAN PHY. These PHYs are solely distinguished by the PCS. There will also be a number of PMD types.
10 GIGABIT ETHERNET IN THE MARKETPLACE
The accelerating growth of worldwide network traffic is forcing service providers, enterprise network managers and architects to look to ever higher-speed network technologies in order to solve the bandwidth demand crunch. Today, these administrators typically use Ethernet as their backbone technology. Although networks face many different issues, 10 Gigabit Ethernet meets several key criteria for efficient and effective high-speed networks:
Â¢ Easy, straightforward migration to higher performance levels without disruption,
Â¢ Lower cost of ownership vs. current alternative technologies â€œ including both acquisition and support costs
Â¢ Familiar management tools and common skills base
Â¢ Ability to support new applications and data types
Â¢ Flexibility in network design
Â¢ Multiple vendor sourcing and proven interoperability
Managers of enterprise and service provider networks have to make many choices when they design networks. They have multiple media, technologies, and interfaces to choose from to build campus and metro connections: Ethernet (100, 1000,and 10,000 Mbps), OC-12 (622 Mbps) and OC-48 (2.488 Gbps), SONET or equivalent SDH network, packet over SONET/SDH (POS), and the newly authorized IEEE 802 Task Force (802.17) titled Resilient Packet Ring.
Network topological design and operation has been transformed by the advent of intelligent Gigabit Ethernet multi-layer switches. In LANs, core network technology is rapidly shifting to Gigabit Ethernet and there is a growing trend towards Gigabit Ethernet networks that can operate over metropolitan area distances.
The next step for enterprise and service provider networks is the combination of multi-gigabit bandwidth with intelligent services, leading to scaled, intelligent, multi-gigabit networks with backbone and server connections ranging up to 10 Gbps.
In response to market trends, Gigabit Ethernet is currently being deployed over tens of kilometers in private networks. With 10 Gigabit Ethernet, the industry has developed a way to not only increase the speed of Ethernet to 10 Gbps but also to extend its operating distance and interconnectivity. In the future, network managers will be able to use 10 Gigabit Ethernet as a cornerstone for network architectures that encompass LANs, MANs and WANs using Ethernet as the end-to-end, Layer 2 transport method.
Ethernet bandwidth can then be scaled from 10 Mbps to 10 Gbps â€œ a ratio of 1 to 1000 â€ without compromising intelligent network services such as Layer 3 routing and layer 4 to layer 7 intelligence, including quality of service (QoS), class of service (CoS), caching, server load balancing, security, and policy based networking capabilities. Because of the uniform nature of Ethernet across all environments when IEEE 802.3ae is deployed, these services can be delivered at line rates over the network and supported over all network physical infrastructures in the LAN, MAN, and WAN. At that point, convergence of voice and data networks, both running over Ethernet, becomes a very real option. And, as TCP/IP incorporates enhanced services and features, such as packetized voice and video, the underlying Ethernet can also carry these services without modification.
As we have seen with previous versions of Ethernet, the cost for 10 Gbps communications has the potential to drop significantly with the development of new technologies. In contrast to 10 Gbps telecommunications lasers, the 10 Gigabit Ethernet short links â€ less than 40km over single-mode (SM) fiber â€ will be capable of using lower cost, uncooled optics and, in some cases, vertical cavity surface emitting lasers (VCSEL), which have the potential to lower PMD costs. In addition, the industry is supported by an aggressive merchant chip market that provides highly integrated silicon solutions. Finally, the Ethernet market tends to spawn highly competitive start-ups with each new generation of technology to compete with established Ethernet vendors.
One of the keys to Ethernetâ„¢s success is the widespread interoperability between vendors. In keeping with its mission to provide resources to establish and demonstrate multi-vendor interoperability of 10 Gigabit Ethernet products, the 10 GEA hosted the worldâ„¢s largest 10 Gigabit Ethernet Interoperability Network in May, 2002. The live, multi-vendor network was on display at the NetWorld+Interop trade show in Las Vegas, Nevada. The network will also be on display at SuperComm, June 4-7, 2002
in Atlanta Georgia.
Comprised of products from 23 vendors, the network included a comprehensive range of products: systems, test equipment, components and cabling. The end-to-end 10GbE network was over 200 kilometers long and showcased five of the seven PMD port types specified in the IEEE 802.3ae draft: 10GBASE-LR, 10GBASE-ER, 10GBASE-SR 10GBASE-LW and 10GBASE-LX4.The network boasted 10 network hops, 18 10 GbE links, and represented all aspects of the technology; WAN, MAN and LAN.As part of the demonstration 12 companies showed chip-to-chip communication over the IEEE 802.3ae XAUI interface.
The collection of products and technologies illustrate years of industry collaboration and signal to the market that 10 Gigabit Ethernet is ready to be deployed and implemented into networks around the world.
APPLICATIONS FOR 10 GIGABIT ETHERNET
10 Gigabit Ethernet in the Metro
Vendors and users generally agree that Ethernet is inexpensive, well understood, widely deployed and backwards compatible from Gigabit switched down to 10 Megabit shared. Today a packet can leave a server on a short-haul optic Gigabit Ethernet port, move cross-country via a DWDM (dense wave division multiplexing) network, and find its way down to a PC attached to a thin coax BNC (Bayonet Neill Concelman) connector, all without any re-framing or protocol conversion. Ethernet is literally everywhere, and 10 Gigabit Ethernet maintains this seamless migration in functionality.
Gigabit Ethernet is already being deployed as a backbone technology for dark fiber metropolitan networks. With appropriate 10 Gigabit Ethernet interfaces, optical transceivers and single mode fiber, service providers will be able to build links reaching 40km or more. (See Figure 4.)
10 Gigabit Ethernet in Local Area Networks
Ethernet technology is already the most deployed technology for high performance LAN environments. With the extension of 10 Gigabit Ethernet into the family of Ethernet technologies, the LAN now can reach farther and support up coming bandwidth hungry applications. Similar to Gigabit Ethernet technology, the 10 Gigabit proposed standard supports both singlemode and multi-mode fiber mediums. However in 10 Gigabit Ethernet, the distance for single-mode fiber has expanded from the 5km that Gigabit Ethernet supports to 40km in 10 Gigabit Ethernet.
The advantage for the support of longer distances is that it gives companies who manage their own LAN environments the option of extending their data centers to more cost-effective locations up to 40km away from their campuses. This also allows them to support multiple campus locations within that 40km range. Within data centers, switch-to-switch applications, as well as switch to server applications, can also be deployed over a more cost effective multi-mode fiber medium to create 10 Gigabit Ethernet backbones that support the continuous growth of bandwidth hungry applications. (See Figure 5.)
With 10 Gigabit backbones installed, companies will have the capability to begin providing Gigabit Ethernet service to workstations and, eventually, to the desktop in order to support applications such as streaming video, medical imaging, centralized applications, and high-end graphics. 10 Gigabit Ethernet will also provide lower network latency due to the speed of the link and over-provisioning bandwidth to compensate for the bursty nature of data in enterprise applications.
10 Gigabit Ethernet in the Storage Area Network
Additionally, 10 Gigabit Ethernet will provide infrastructure for both network-attached storage (NAS) and storage area networks (SAN). Prior to the introduction of 10 Gigabit Ethernet, some industry observers maintained that Ethernet lacked sufficient horsepower to get the job done. Ethernet, they said, just doesnâ„¢t have what it takes to move dump truck loads worth of data. 10 Gigabit Ethernet, can now offer equivalent or superior data carrying capacity at similar latencies to many other storage networking technologies including 1 or 2 Gigabit Fiber Channel, Ultra160 or 320 SCSI, ATM OC-3, OC-12 & OC-192,and HIPPI (High Performance Parallel Interface). While Gigabit Ethernet storage servers, tape libraries and compute servers are already available, users should look for early availability of 10 Gigabit Ethernet end-point devices in the second half of 2001.
There are numerous applications for Gigabit Ethernet in storage networks today, which will seamlessly extend to 10 Gigabit Ethernet as it becomes available. (See Figure 6.) These include:
Â¢ Business continuance/disaster recovery
Â¢ Remote backup
Â¢ Storage on demand
Â¢ Streaming media
10 Gigabit Ethernet in Wide Area Networks
10 Gigabit Ethernet will enable Internet service providers (ISP) and network service providers (NSPs) to create very highspeed links at a very low cost, between co-located, carrier-class switches and routers and optical equipment that is directly attached to the SONET/SDH cloud. 10 Gigabit Ethernet with the WAN PHY will also allow the construction of WANs that connect geographically dispersed LANs between campuses or POPs (points of presence) over existing SONET/SDH/TDM networks. 10 Gigabit Ethernet links between a service providerâ„¢s switch and a DWDM (dense wave division multiplexing) device or LTE (line termination equipment) might in fact be very short â€ less than 300 meters. (See Figure 7.)
THE 10 GIGABIT ETHERNET TECHNOLOGY 10GBE CHIP INTERFACES
Among the many technical innovations of the 10 Gigabit Ethernet Task Force is an interface called the XAUI (10 Gigabit Attachment Unit Interface). It is a MAC-PHY interface, serving as an alternative to the XGMII (10 Gigabit Media Independent Interface). XAUI is a low pin-count differential interfaces that enables lower design costs for system vendors.
The XAUI is designed as an interface extender for XGMII, the 10 Gigabit Media Independent Interface. The XGMII is a 74 signal wide interface (32-bit data paths for each of transmit and receive) that may be used to attach the Ethernet MAC to its PHY. The XAUI may be used in place of, or to extend, the XGMII in chip-to-chip applications typical of most Ethernet MAC to PHY interconnects. (See Figure 8.)
The XAUI is a low pin count, self-clocked serial bus that is directly evolved from the Gigabit Ethernet 1000BASE-X PHY. The XAUI interface speed is 2.5 times that of 1000BASE-X. By arranging four serial lanes, the 4-bit XAUI interface supports the ten-times data throughput required by 10 Gigabit Ethernet.
PHYSICAL MEDIA DEPENDENT (PMDS)
The IEEE 802.3ae Task Force has developed a draft standard that provides a physical layer that supports link distances for fiber optic media as shown in Table A.
To meet these distance objectives, four PMDs were selected. The task force selected a 1310 nanometer serial PMD to meet its 2km and 10km single-mode fiber (SMF) objectives. It also selected a 1550 nm serial solution to meet (or exceed) its 40km SMF objective. Support of the 40km PMD is an acknowledgement that Gigabit Ethernet is already being successfully deployed in metropolitan and private, long distance applications. An 850 nanometer PMD was specified to achieve a 65-meter objectiveover multimode fiber using serial 850 nm transceivers.
Additionally, the task force selected two versions of the wide wave division multiplexing (WWDM) PMD, a 1310 nanometer version over single-mode fiber to travel a distance of 10km and a 1310 nanometer PMD to meet its 300-meter-over-installedmultimode- fiber objective.
Physical Layer (PHYs)
The LAN PHY and the WAN PHY will operate over common PMDs and, therefore, will support the same distances. These PHYs are distinguished solely by the Physical Encoding Sublayer (PCS). (See Figure 7.) The 10 Gigabit LAN PHY is intended to support existing Gigabit Ethernet applications at ten times the bandwidth with the most cost-effective solution. Over time, it is expected that the LAN PHY will be used in pure optical switching environments extending over all WAN distances. However, for compatibility with the existing WAN network, the 10 Gigabit Ethernet WAN PHY supports connections to existing and future installations of SONET/SDH (Synchronous Optical Network/ Synchronous Digital Hierarchy) circuit-switched telephony access equipment.
The WAN PHY differs from the LAN PHY by including a simplified SONET/SDH framer in the WAN Interface Sublayer (WIS). Because the line rate of SONET OC-192/ SDH STM-64 is within a few percent of 10 Gbps, it is relatively simple to implement a MAC that can operate with a LAN PHY at 10 Gbps or with a WAN PHY payload rate of approximately 9.29 Gbps. (See Figure 9.). Appendix III provides a more in depth look at the WAN PHY.
As the Internet transforms longstanding business models and global economies, Ethernet has withstood the test of time to become the most widely adopted networking technology in the world. Much of the worldâ„¢s data transfer begins and ends with an Ethernet connection. Today, we are in the midst of an Ethernet renaissance spurred on by surging E-Business and the demand for low cost IP services that have opened the door to questioning traditional networking dogma. Service providers are looking for higher capacity solutions that simplify and reduce the total cost of network connectivity, thus permitting profitable service differentiation, while maintaining very high levels of reliability.
Enter 10 Gigabit Ethernet. Ethernet is no longer designed only for the LAN. 10 Gigabit Ethernet is the natural evolution of the well-established IEEE 802.3 standard in speed and distance. It extends Ethernetâ„¢s proven value set and economics to metropolitan and wide area networks by providing:
Â¢ Potentially lowest total cost of ownership (infrastructure/operational/human capital)
Â¢ Straightforward migration to higher performance levels
Â¢ Proven multi-vendor and installed base interoperability (Plug and Play)
Â¢ Familiar network management feature set
An Ethernet-optimized infrastructure build out is taking place. The metro area is currently the focus of intense network development to deliver optical Ethernet services. 10 Gigabit Ethernet is on the roadmaps of most switch, router and metro optical system vendors to enable:
Â¢ Cost effective Gigabit-level connections between customer access gear and service provider POPs (points of presence) in native Ethernet format
Â¢ Simple, very high speed, low-cost access to the metro optical infrastructure
Â¢ Metro-based campus interconnection over dark fiber targeting distances of 10/40km and greater
Â¢ End to end optical networks with common management systems
Â¢ IEEE 802 LAN/MAN Standards Committee
Â¢ IEEE 802.3 CSMA/CD (ETHERNET)
Â¢ IEEE P802.3ae 10Gb/s Ethernet Task Force
2. 10 GIGABIT ETHERNET TECHNOLOGY OVERVIEW
3. THE 10 GIGABIT ETHERNET ALLIANCE
4. THE 10 GIGABIT ETHERNET STANDARD
5. THE 10 GIGABIT ETHERNET IN THE MARKET PLACE
6. INTEROPERABILITY DEMOS
7. APPLICATIONS FOR 10 GIGABIT ETHERNET
8. 10 GIGABIT ETHERNET TECHNOLOGY 10GbE CHIP INTERFACES
9. PHYSICAL MEDIA DEPENDENT (PMDs)
Since its inception at Xerox Corporation in the early 1970s, Ethernet has been the dominant networking protocol. Of all current networking protocols, Ethernet has, by far, the highest number of installed ports and provides the greatest cost performance relative to Token Ring, Fiber Distributed Data Interface (FDDI), and ATM for desktop connectivity. Fast Ethernet, which increased Ethernet speed from 10 to 100 megabits per second (Mbps), provided a simple, cost-effective option for backbone and server connectivity.
10 Gigabit Ethernet builds on top of the Ethernet protocol, but increases speed tenfold over Fast Ethernet to 10000 Mbps, or 10 gigabit per second (Gbps). This protocol, which was standardized in august 2002, promises to be a dominant player in high-speed local area network backbones and server connectivity. Since10 Gigabit Ethernet significantly leverages on Ethernet, customers will be able to leverage their existing knowledge base to manage and maintain gigabit networks.
The purpose of this technology brief is to provide a technical overview of 10 Gigabit Ethernet. This paper discusses:
Â¢ The architecture of the Gigabit Ethernet protocol, including physical interfaces, 802.3x flow control, and media connectivity options
Â¢ The 10 Gigabit Ethernet standards effort and the timing for Gigabit Ethernet
Â¢ 10 Gigabit Ethernet topologies
Â¢ Migration strategies to 10 Gigabit Ethernet
I express my sincere thanks to Prof. M.N Agnisarman Namboothiri (Head of the Department, Computer Science and Engineering, MESCE), Mr. Sminesh (Staff incharge) for their kind co-operation for presenting the seminar and presentation.
I also extend my sincere thanks to all other members of the faculty of Computer Science and Engineering Department and my friends for their co-operation and encouragement.
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Ten Gigabit Ethernet.doc (Size: 208 KB / Downloads: 61)
The Te" Gigabit Ethernet standard extends the IEEE 802.3ae standard protocols to a wire speed of Ten Gbps and expands the Ethernet application space to include WAN compatible links. The Ten Gigabit Ethernet standard provides a significant increase in bandwidth while maintaining maximum compatibility with the installed base of 802.3 standard interfaces, protects previous investment in research and development, and retains the existing principles of network operation and management.
Under the Open Systems Interconnection (OSI) model, Ethernet is fundamentally a Layer 1 and 2 protocols. The Ten-Gigabit Ethernet retains key Ethernet architecture, including the Media Access Control (MAC) protocol, the Ethernet frame format, and the minimum and maximum frame size. TheTen-Gigabit Ethernet continues the evolution of Ethernet in speed and distance, while retaining the same Ethernet architecture used in other Ethernet specifications, except for one key ingredient. Since Ten Gigabit Ethernet is a full-duplex only technology, it does not need the carrier-sensing multiple-access with collision detection (CSMA/CD) protocol used in other Ethernet technologies. In every other respect, Ten Gigabit Ethernet matches the original Ethernet model.
At the physical layer (Layer 1), an Ethernet physical layer device (PHY) connects the optical or copper media to the MAC. layer. Ethernet architecture further divides the physical layer into three sub layers: Physical Medium Dependent (PMD), Physical Medium Attachment (PMA), and Physical Coding Sub layer (PCS). PMDs provide the physical connection and signaling to the medium; optical transceivers, for example, are PMDs. The PCS consists of coding (e.g., 64B/66B) and a serializer or multiplexer. The IEEE 802.3ae standard defines two PHY types: the LAN PHY and the WAN PHY. They provide the same functionality, except the WAN PHY has an extended feature set in the PCS that enables connectivity with SONET STS-192c/SHD VC-4-64c networks.
The application of Ten-Gigabit Ethernet are in the areas of Local Area Networks, Fabric Interconnect. Wide Area Networks . Metropolitan and Storage Applications
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Over the past several years, Ethernet has been the most popular choice of technology for local area networks (LAN). There are millions of Ethernet users worldwide and still counting. In 1998, the standard for One Gigabit Ethernet was released. It prompted a great deal of attention from users, especially many of those who were reluctant to adopt the expensive ATM technology for their LANs. As demand for high speed networks continued to grow, the need for a faster Ethernet technology was apparent. In March 1999, a working group was formed at IEEE 802.3 Higher Speed Study (HSSG) to develop a standard for Ten-Gigabit Ethernet.
The Ten Gigabit Ethernet is basically the faster speed version of Ethernet. It will support the data rate of 10 Gb/s. it offers similar benefits to those of those preceding Ethernet standard. However, it will not support half duplex operation mode. The potential applications and markets for Ten Gigabit Ethernet are enormous. There are broad groups of users who demand Ten Gigabit Ethernet, for example, enterprise users, universities, telecommunication carriers, and Internet service providers. Each market typically has different requirements for link span and cost.
Proving the initial skeptics wrong, Ten Gigabit Ethernet has found widespread acceptance. Companies are opting for Ten Gigabit Ethernet switches more as a norm than as an exception, in order to protect their investment, even if they don't need these immediately. The market has witnessed a growth of 30 per cent, also due to an exceptional surge in innovation, dictated by the needs of the market. The Ten Gigabit market has grown 66 per cent in 2004 over the previous year.
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Ten Gigabit Ethernet Overview
The Ethernet protocol basically implements the bottom two layers of the Open Systems Interconnection(OSI) 7-layer model i.e., the data link layer and physical sublayers.Figure-1 depicts the typical Ethernet protocol stack and the relationship to the OSI model. Details of each layer are given below:
Medium Access Control (MAC)
The media access control sub layer provides a logical connection between the MAC clients of itself and its peer station. Its main responsibility is to initialize, control and manage the connection with peer station.
Reconciliation Sub layer
Figure 1 .Ethernet Protocol Layer
The reconciliation sub layer acts as a command translator. It maps the terminology and commands used in the MAC layer into electrical formats appropriate for the physical layer entities.
Media Independent TenGMII (Ten-Gigabit Interface)
Ten-GMU provides a standard interface the MAC layer and the physical layer. It isolates the MAC layer and the physical layer, enabling the MAC layer to be used with various implementations of the physical layer.
PCS (Physical Coding Sub layer)
The PCS sub layer is responsible for coding and encoding data stream from the MAC layer. Several coding techniques is explained later.
PMA (Physical Medium Attachment)
The PMD sub layer is responsible for serialize code groups into bit stream suitable for serial bit-oriented physical devices and vice versa. Synchronization is also done for proper data decoding in this sub layer..
PMDfPhvsical Medium Dependent)
The PMD sub layer is responsible for signal transmission. The typical PMD functionality includes amplifier, modulation and wave shaping. Different PMD devices may support different media.
MDKMedium Dependent Interface)
MDI is referred as a connector. It defines different connector types for different physical media and PMD devices.
More on Ten Gigabit Ethernet MAC Layer
The medium access control layer of Ten Gigabit Ethernet is similar to the MAC layer of previous Ethernet technologies. It uses the same Ethernet address and frame formats, but it does not support full duplex mode. It will support data rate of Ten GB/s and lower, using pacing mechanism for rate adaptation and flow controls.
In the Ethernet standard there are two modes of operation: half duplex and full "duplex modes. The half-duplex mode has been defined since the original version of Ethernet. In
this mode, data are transmitted using the popular Carrier-Sense Multiple access/Collision Detection (CSMA/CD) protocol on a shared medium. Its simplicity contributed to the success of the Ethernet standard. The main disadvantages of the half-duplex are the efficiency and distance limitation.
In this mode, the link distance is limited by the minimum MAC frame size. This restriction reduces the efficiency drastically for high rate transmission. Most of the links at this rate are point-to-point over optical fibers. In this case, the full duplex operation is preferred. In the full duplex operation, there is no contention. The MAC layer entity can transmit whenever it wants, provided that its peer is ready to receive. The distance of the link is limited by the characteristic of the physical medium and devices, power budgets and modulation.
MAC Frame Format
The key purpose for developing Ten-Gigabit Ethernet standard is to use the same MAC frame format as specified in the preceding Ethernet standards. This will allow a seamless integration of the Ten-Gigabit Ethernet with the Existing Ethernet networks. There is no need for fragmentation or reassembling and the address translation, implying faster switching. The minimum MAC frame format is made equal to 64 octets as specified in the previous Ethernet standards.
6 octets 6 octets
Destination Address Source Address Length/Type MAC client data Padding
Order of Transmission
Frame checking sequence
Figure 2: Ethernet Frame Format
The Ethernet frame format consists of the following fields
A 7-octect preamble pattern of alternating O's and l's that is used to allow receiver synchronization to reach a steady state.
> Start frame delimiter (SFD)
The SFD field is the sequence TenTenTenl 1, used to allow receiver timing to indicate a start of frame.
> Address fields
Each MAC frame contains the destination and source addresses. Each address is 48 bits long. The first of which is used to identify the address as an individual address (0) or a group address (1). The second of which is used to indicate whether the address is locally (1) or globally (0) defined.
If the number is less than maximum valid frame size, it indicates the length of the MAC client data. If the number is greater than or equal to 1536 decimal, it represents the type of the MAC client protocol.
> Data and padding
Padding is optional. It is only necessary when the data packet is smaller than 38 octets to ensure the minimum frame size of 64 octets as specified in the existing standards.
> Frame Checking Sequence (FCS)
The FCS field contains a 32-bit cyclic redundancy check (CRC) value computed from all fields except the preamble, SFD and CRC. The encoding is defined by a generating polynomial.
LAN's require a Ten Gigabit Ethernet so that a Ten Gigabit Ethernet switch can support exactly ten One Gigabit Ethernet ports, while WANs require the 9.584640 Gb/s data
rate so that it is compatible with the OC-192 rate. The solution to this problem supports both the rates. This can be done by specifying the data rate at 10 Gb/s and utilizing pacing mechanism to accommodate the slower data rates.
The pacing mechanism allows the MAC layer to support transmission rates, for instance. 1 GB/s or 10 GB/s for LAN and 9.584640 GB/s for WAN. To achieve this, the MAC layer entity shall have an ability to pause data transmission for an appropriate period of time to provide a flow control or rate adaptation. Two techniques for pacing mechanism are under consideration.
The first is the word-by-word hold technique and the second is the Inter-Frame GAP(IFG) stretch technique. In the word-by-word technique, the MAC layer entity pauses sending a 32-bit word of data for a pre-specified period of time upon request from the physical layer. In the IPG technique, the IFG is extended for a pre-defined period of time with or without a request from the physical layer.
The main disadvantage of the IPG stretch technique is that a large data buffer is required because the algorithm operates between frames. The main advantages of the word-byÃ‚Â¬word mechanism are that it can support any encoding techniques, it does not need a large data buffer to hold multiple MAC frames, and the buffer size is independent of link speed.
The Ten-Gigabit Ethernet Physical Layer
The main issues include Ten Gigabit Media Interface, parallel vs. serial architectures, wavelength division multiplexing (WDM) vs. parallel optic, coding techniques, devices, media and so on.
The Ten-Gigabit Media Independent Interface (TenGMII)
The GMII provides the interface between the MAC layer and the physical layer. It allows the MAC layer to support various physical layer variations. The TX_word_hold line is provided to support word oriented pacing mechanism. The 32-but data paths are provided for transmit and receive functions each with 4 control bits. The control bit is
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set to "1" for delimiters and special characters and "0" for data. Delimiters and special characters are determined from the 8 bit data value when the control bit is set to "0". The delimiter and special characters include:
32 Data bits
32 Data bits
Figure 3. GMII
> IDLE which is signaled during the inter-packet gap and when there is no data to send.
> SOP which is signaled at the start of each packet
> EOP which is signaled at the end of each packet
> ERROR which is signaled when an error is detected in the received signal or when an error needs to be put to the translated signal.
These delimiter and special characters enables a proper synchronization or multiplexing and demultiplexing operations. It should be noted that the interface could also be scaled in speed and width.
Physical Layer Architecture
There are two structures for the physical layer implementation of Ten-Gigabit Ethernet: the serial solution and parallel solution. The serial solution uses one high speed (TenGb/s) PCS/PMA/PMD circuit block and the parallel solution uses multiple PCS/PMA/PMD circuit blocks at lower speed
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i) Serial implementation
In the serial implementation, there is one physical channel operating at Ten Gb/s. The operation is straightforward. For transmission, the reconciliation module passes the signals, corresponding to the MAC data, word-by-word to the PCS module. The PCS module then encodes the signals with pre-defined coding technique and passes the encoded signal to the PMA module. The PMA module then serializes the encoded signals and passes the stream to the PMD module.
MEDIUM TenG bis
Figure 4.Serial Physical layer Implementation
The PMD module transmits the signal stream over the fiber at TenGb/s. for receiving the process is the reverse. The main advantage of the serial architecture is that the transmitting/receiving operation is straightforward. It does not require a complicated multiplexing/ demultiplexing that is needed in the parallel implementation. Thus the timing jitter requirement is more relaxed. It also requires only one fiber channel and one set of laser equipment. The main disadvantage is the need of expensive high-speed logic circuits technology. To reduce transmission rate, higher-rate coding techniques such as PAM-5 and MB8Ten may be used. There are technologies, for example the TenG-SONET/OC-192, which currently support TenGb/s operation. The technologies from these existing standards may be borrowed to aid the TenG Ethernet serial implementation.
ii) Parallel Implementation
In parallel implementation, there are multiple physical channels, say sub-channels that may be implemented by using parallel cables or WDM multiplexing. For transmission, the distributor multiplexes the data (frames and idles) accepted from the MAC layer into n streams in the Round-Round motion. Each stream is given to each PMA module for serialization. After serialization, each PMD module transmits each serialized data stream at the rate of Ten/n Gb/s. The main advantage of the parallel implementation is that the operating rate in the PCS/PMA modules is reduced, which enables cheaper devices to be used. The disadvantages are the need of distributor/collector module that may be sensitive to timing jitters, and the usage of multiple sets of logic circuits and laser equipment. There are two techniques to achieve multiple channels, one of which is the parallel cabling and the other is the WDM.
n n n
PCS PCS PCS
PMA PMA PMA
PMD 1 PMD 2 PMD
MEDIUM Ten/n G b/s I
Figure 5.Parallel Physical Layer Implementation
An essential component for high speed transmission is laser. There are several types of lasers. The common ones are the Fabry-Perot(F-P) Laser, Vertical-Cavity Surface-Emitting Laser(VCSEL), and Distributed-Feedback (DFB) Laser.
> Fabry-Perot Laser
The Fabry-Perot laser is simple low cost multi-mode laser. It is optimized for single mode fibers but it can also operate over multi-mode fibers. The typical operating wavelength is in the 1300-nm range. For this type of optical source, the distance limitation is due to dispersion and mode-partition noise.
> Vertical-Cavity Surface Emitting Laser(VCSEL)
The VCSEL laser is traditionally a low cost solution for 850-nm application. It can operate on both multi-mode and single mode fibers. For this type of source, the link-distance is quite limited.
> Distributed-Feedback Laser
The Distributed-Feedback laser utilizes distributed resonators to suppress multi-mode source. It has high bandwidth-distance product and typically operates over the 1300-nm wavelength band on single mode and multi-mode fibers, and 1550-nm band on single mode fibers. The distance limitation is typically due to attenuation loss for the 1300-nm band and dispersion for the 1550-nm band.
The physical media for high speed transmission are typically fibers.
> 62.5-um Multi-mode Fiber
62.5-um multi-mode fiber is the cheapest among the applicable choices of fibers. Most of the existing fiber infrastructures for links up to 300 meters are 62.5-um multi-mode fibers. It typically supports operations in the 800 nm and 1300 nm wavelength bands. The performance of this type of fiber is typically limited at about 200MHz km limiting the link distance to less than 50 maters for a line rate about TenGBaud.
> 50-um Multi-mode Fiber
The traditional 50-um multi-mode fiber has sloght better performance than the 62.5-um multi-mode fiber. In this case, link distance is limited to less than 65 meters at about Ten Gbaud line rate. However, the new enhanced 50-um multi-mode fibers such as
ZETA by Lucent have better performance. For this type of fibers, the line rate is 12.5 GBaud for link distance up to 300 meters.
> Single Mode Fiber
The single mode fiber has smaller core than the multi-mode fiber, enabling signals to travel much longer distance. At the line rate about TenGBaud, the link can be as long as 40 km. in practice, the single-mode fibers are suitable for LAN backbones, MAN and WAN.
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Ten Gigabit Ethernet in the Marketplace
Ethernet technology is currently the most deployed technology for high-performance LAN environments. Enterprises around the world have invested cabling, equipment, processes, and training in Ethernet. In addition, the ubiquity of Ethernet keeps its costs low, and with each deployment of next-generation Ethernet technology, deployment costs have trended downward. In networks today, the increase in worldwide network traffic is driving service providers, enterprise network managers and architects to look to faster network technologies to solve increased bandwidth demands. Ten Gigabit Ethernet has ten times the performance over Gigabit Ethernet today.
With the addition of Ten Gigabit Ethernet to the Ethernet technology family, a LAN now can reach further distances and support even more bandwidth hungry applications. Ten Gigabit Ethernet also meets several criteria for efficient and effective high-speed network performance, which makes it a natural choice for expanding, extending, and upgrading existing Ethernet networks.
A customer's existing Ethernet infrastructure is easily interoperable with Ten Gigabit Ethernet. The new technology provides lower cost of ownership including both acquisition and support costs versus current alternative technologies.
> Using processes, protocols, and management tools already deployed in the
management infrastructure, Ten Gigabit Ethernet draws on familiar
management tools and a common skills base.
Flexibility in network design with server, switch, and router connections r- Multiple vendors sourcing of standards-based products provide proven interoperability.
As Ten Gigabit Ethernet enters the market and equipment vendors deliver Ten Gigabit Ethernet network devices, the next step for enterprise and service provider networks is the combination of multi-gigabit bandwidth with intelligent services, which leads to scaled, intelligent, multi-gigabit networks with backbone and server connections
ranging up to Ten Gbps. Convergence of voice and data networks running over Ethernet becomes a very real option.
And, as TCP/IP incorporates enhanced services and features, such as packetized voice and video, the underlying Ethernet can also carry these services without modification. The Ten Gigabit Ethernet standard not only increases the speed of Ethernet to Ten Gbps, but also extends its interconnectivity and its operating distance up to 40 km. Like Gigabit Ethernet, the Ten Gigabit Ethernet standard (IEEE 802.3ae) supports both single mode and multimode fiber mediums. However, in Ten Gigabit, the distance for single-mode (SM) fiber has expanded from 5 km in Gigabit Ethernet to 40 km in Ten Gigabit Ethernet. The advantage of reaching new distances gives companies who manage their own LAN environments the option to extend their data center to a more cost-effective location up to 40 km away from their campuses. This also allows them to support multiple campus locations within the 40 km distance.
As it is evident from the previous versions of Ethernet, the cost for Ten Gbps communications has the potential to drop significantly with the development of Ten Gigabit Ethernet-based technologies. Compared to Ten Gbps telecommunications lasers, theTen Gigabit Ethernet technology, as defined in the IEEE 802.3ae will be capable of using lower cost, non-cooled optics, and vertical cavity surface emitting lasers (VCSEL), which can lower PMD device costs. In addition, an aggressive merchant chip market that provides highly integrated silicon solutions supports the industry.
Dept. of CSE
Applications of Ten Gigabit Ethernet
Vendors and users generally agree that Ethernet is inexpensive, well understood, widely deployed and backwards compatible in today's LAN networks. Today, a packet can leave a server on a short-haul optic Gigabit Ethernet port, move cross-country via a DWDM (dense-wave division multiplexing) network, and find its way down to a PC attached to a Gigabit copper port, all without any re-framing or protocol conversion. Ethernet is literally everywhere, and Ten Gigabit Ethernet maintains this seamless migration in functionality for any application in which Ethernet can be applied.
y Gigabit Ethernet as a Fabric Interconnect
Fabric interconnects, whether they are for server area networks or storage area networks, have traditionally been the domain of dedicated, often proprietary, networks with relatively small user bases when compared to Ethernet. These server area networks include InfiniBand, Servernet, Myranet, Wulfkit and Quadrics technologies, and offer excellent bandwidth and latency performance for very short-haul (generally less than 20 m) networks.
However, with the exception of InfiniBand, these are proprietary networks that can be difficult to deploy and maintain due to the small number of experienced IT professionals familiar with the technology. The small volumes also result in higher costs for server adapters and switches. And, as with any proprietary solution, they are not interoperable with other technologies without the appropriate routers and switches.
In storage area networks, the lack of standards and a slew of interoperability problems plagued the early Fibre Channel deployments. However, these technologies also suffer similar problems as those seen by proprietary server area networks in that they are considered difficult to deploy due to lack of a skilled IT pool, are relatively expensive at the adapter and switch port, are still not directly interoperable with other network technologies without expensive routers or switching devices, and generally focus on short-haul deployments.
Ten Gigabit Ethernet is in a position to replace these proprietary technologies as a next-generation interconnects for both server and storage-area networks for several reasons which are:
* Ten Gigabit Ethernet Offers the Necessary Bandwidth.
In fact, InfiniBand and Fibre Channel will also begin mass deployments of Ten
Gigabit technologies, indicating a convergence on Ten Gigabit throughput.
*Cost-Saving Server Consolidation.
Ten Gigabit Ethernet grants a single server the bandwidth needed to replace several servers that were doing different jobs. Centralization of management is also a major benefit of server consolidation . With a single powerful server, IT Managers can monitor, manage, and tune servers and application resources from a single console which saves time and maximizes IT resources.
*Planned Growth of Ten Gigabit Network Features.
For the first time ever, Ethernet can be a low-latency network due to RDMA (Remote Direct Memory Access) support, which is critical in the server-to-server communication typically associated with clustering and server area networks.
> Gigabit Ethernet in Local Area Networks
Ethernet technology is already the most deployed technology for high-performance LAN environments. With the extension of Ten Gigabit Ethernet into the family of Ethernet technologies, LANs can provide better support the rising number of bandwidth hungry applications and reach greater distances. Similar to Gigabit Ethernet technology, the Ten Gigabit standard supports both single-mode and multimode fiber media.
With links up to 40 km, Ten Gigabit Ethernet allows companies that manage their own LAN environments the ability to strategically choose the location of their data center and server farms - up to 40 km away from their campuses. This enables them to support multiple campus locations within that 40 km range. Within data centers, switch-to-switch applications, as well as switch-to-server applications, can be deployed over a more cost-effective, short-haul, multi-mode fiber medium to create Ten Gigabit Ethernet backbones that support the continuous growth of bandwidth-hungry applications.
With Ten Gigabit backbones, companies can easily support Gigabit Ethernet connectivity in workstations and desktops with reduced network congestion, enabling greater implementation of bandwidth-intensive applications, such as streaming video, medical imaging, centralized applications, and high-end graphics. Ten Gigabit Ethernet also improves network latency, due to the speed of the link and over-provisioning bandwidth, to compensate for the bursty nature of data in enterprise applications.
The bandwidth that Ten Gigabit backbones provide also enables the next generation of network applications. It can help make telemedicine, telecommuting, distance learning and interactive, and digital videoconferencing everyday realities instead of remote future possibilities.
Ten Gigabit Ethernet enables enterprises to reduce network congestion, increase use of bandwidth-intensive applications, and make more strategic decisions about the location of their key networking assets by extending their LAN up to 40 km.
> Gigabit Ethernet in Metropolitan and Storage Applications
Gigabit Ethernet is already being deployed as a backbone technology for dark fiber metropolitan networks. With appropriate Ten Gigabit Ethernet interfaces, optical transceivers and single mode fiber, network and Internet service providers will be able to build links reaching 40 km or more , encircling metropolitan areas with city-wide networks.
Ten Gigabit Ethernet now enables cost-effective, high-speed infrastructure for both network attached storage (NAS) and storage area networks (SAN). Prior to the introduction of Ten Gigabit Ethernet, some industry observers maintained that Ethernet lacked sufficient horsepower to get the job done. Ten Gigabit Ethernet can now offer equivalent or superior data carrying capacity at latencies similar to many other storage
There are numerous applications for Gigabit Ethernet today, such as back-up and database mining. Some of the applications that will take advantage of Ten Gigabit Ethernet is:
Â¢ Business continuance/disaster recovery
Â¢ Remote back-up
Â¢ Storage on demand
Â¢ Streaming media
> Ten Gigabit Ethernet in Wide Area Networks
Ten Gigabit Ethernet enables ISPs and NSPs to create very high speed links at a very low cost from co-located, carrier-class switches and routers to the optical equipment, directly attached to the SONET/SDH cloud. Ten Gigabit Ethernet, with the WAN PHY, also allows the construction of WANs that connect geographically dispersed LANs between campuses or points of presence (POPs) over existing SONET/SDH/TDM networks. Ten Gigabit Ethernet links between a service provider's switch and a DWDM device or LTE (line termination equipment) might in fact be very short - less than 300 meters.
Ethernet has withstood the test of time to become the most widely adopted networking technology in the world. With the rising dependency on networks and the increasing number of bandwidth-intensive applications, service providers seek higher capacity networking solutions that simplify and reduce the total cost of network connectivity, thus permitting profitable service differentiation, while maintaining very high levels of reliability. The Ten Gigabit Ethernet IEEE 802.3ae Ten Gigabit Ethernet standard is proving to be a solid solution to network challenges. Ten Gigabit Ethernet is the natural evolution of the well-established IEEE 802.3ae standard in speed and distance. In addition to increasing the line speed for enterprise networks, it extends Ethernet's proven value set and economics to metropolitan and wide area networks by providing:
> Potentially lowest total cost-of-ownership(infrastructure/operational/human capital)
> Straight-forward migration to higher performance levels
> Proven multi-vendor and installed-base interoperability(Plug and Play)
> Familiar network management feature set
An Ethernet-optimized infrastructure is taking place in the metropolitan area and many metropolitan areas are currently the focus of intense network development intending to deliver optical Ethernet services. Ten Gigabit Ethernet is on the roadmap of most switch, router and metropolitan optical system vendors to enable:
> Cost-effective, Gigabit-level connections between customer access gear and service provider POPs in native Ethernet format.
> Simple, high-speed, low-cost access to the metropolitan optical infrastructure.
> Metropolitan-based campus interconnection over dark fiber, targeting distances of Ten to 40 km.
> End-to-end optical networks with common management systems.
IEEE 802.3 had recently formed two new study groups to investigate Ten Gigabit Ethernet over copper cabling. The TenGBASE-CX4 study group has developed a standard called as IEEE 802.3ak, for transmitting and receiving signals via a 4-pair twinax cable, commonly referred to as a 4x InfiniBand cable. The goal of the study group was to provide a standard for a low-cost inter-rack and rack-to-rack solution. The TenGBASE-T study group is developing a standard for the transmission and reception of Ten Gigabit Ethernet via a Category 5 or better unshielded twisted pair (UTP) copper cable up to TenO m .
The Ten Gigabit Ethernet is the low cost solution for high speed and reliable data networking and is most likely to be used extensively in LAN, MAN and WAN, implying technology convergence and faster switching , and even in fields as diverse as animation and supercomputing.
4. intel.com 3. cisco.com
TEN GIGABIT ETHERNET OVERVIEW 2
TEN GIGABIT ETHERNET IN THE MARKETPLACE 12
APPLICATIONS OF TEN GIGABIT ETHERNET 14
FUTURE SCOPE 19