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Network and Optical Industry Common Terminology

[ Bridge | Class 1M | Dark Fiber | DWDM | Extended Availability | FDDI | HFC | ICMP | IEC | IGMP | IP | ISDN | MPLS | OC | OSI Model | Packet Switching | PON | Router | SDH | SONET | Switch | TCP/IP | UTP | VCSEL Lasers | VLAN | VPN | WDM | 100BASE-T ]

Bridge

A device that connects two local-area networks (LANs), or two segments of the same LAN. The two LANs being connected can be alike or dissimilar. For example, a bridge can connect an Ethernet with a Token-Ring network. Unlike routers, bridges are protocol-independent. They simply forward packets without analyzing and re-routing messages. Consequently, they're faster than routers but also less versatile.

Class 1M

Class 1M laser products have a wavelength range of 302.5 to 106nm. Class 1M products are safe to eyes and skin under normal conditions, including when users view the laser beam directly.

Dark Fiber

Dark fiber refers to unused fiber-optic cable. Often, companies lay more fiber lines than what's needed at the moment to curb costs. The dark strands can be leased to individuals or other companies that want to establish optical connections among their own locations. Under such a scenario, the fiber is neither controlled by nor connected to the local phone company. Instead, the company or individual provides the necessary components to make it functional.

DWDM

Dense Wavelength Division Multiplexing is an optical technology used to increase bandwidth over existing fiber-optic backbones. DWDM works by combining and transmitting multiple signals simultaneously at different wavelengths on the same fiber. In effect, one fiber is transformed into multiple virtual fibers. A key advantage of DWDM is that it's protocol and bit-rate independent. DWDM-based networks can transmit data in IP, ATM, SONET/SDH, and Ethernet, and handle bit-rates between 100 Mb/s and 2.5 Gbps.

Extended Availability

Extended Availability, based on DualPath Architectecture for Outdoor Wireless is the combination (blending) of two market-adopted Outdoor Wireless technologies to provide the highest available connectivity throughput and network uptime, more commonly referred to as "network availability". Only through an integrated, combined Outdoor Wireless solution can shortcomings of current stand-alone Outdoor Wireless products be addressed, resulting in new and improved alternatives for enterprises and mobile carriers seeking to deploy point-to-point connections with true fiber-optic capacity and coveted 99.999% network availability. No standalone Outdoor Wireless product today can provide this fiber-like performance - let alone provide it both easily and economically. DualPath Architecture for Outdoor Wireless is a proprietary design platform patented by LightPointe in the United States and Europe (US 6,763,195 B1; AND EP 1 249 084 B1).

FDDI

Fiber Distributed Data Interface is a set of ANSI protocols for sending digital data over fiber optic cable. FDDI networks are token-passing networks, and support data rates of up to 100 Mbps. FDDI networks are typically used as backbones for wide-area networks. An extension to FDDI, called FDDI-2, supports the transmission of voice and video information as well as data. Another variation of FDDI, called FDDI Full Duplex Technology (FFDT) uses the same network infrastructure but can potentially support data rates up to 200 Mbps.

HFC

Hybrid Fiber Coax is a way of delivering video, voice telephony, data, and other interactive services over coaxial and fiber optic cables. An HFC network works consists of a head-end office, distribution center, fiber nodes, and network interface units. The head-end office receives information such as television signals, Internet packets, and streaming media, and then delivers them through a SONET ring to distribution centers. The distribution centers then send the signals to neighborhood fiber nodes, which convert the optical signals to electrical signals and redistributes them on coaxial cables to residents' homes where network interface units send the appropriate signals to the appropriate devices (i.e. television, computer, telephone).

ICMP

Internet Control Message Protocol is an extension to the Internet Protocol (IP) defined by RFC 792. ICMP supports packets containing error, control, and informational messages. The PING command, for example, uses ICMP to test an Internet connection.

IEC

The International Electrotechnical Commission (IEC), www.iec.ch/, is the leading global organization that establishes international standards for electronics, electro-optics, and related technologies. For laser product manufacturers, this means that IEC creates safety standards that work to improve the quality of laser products, as well as to improve human safety. Specifically, Amendment 2 of IEC standard 60825-1 lays out the safety regulations that laser manufacturing companies must meet in order to be compliant. In January 2004, our laser diode products officially met all European standards for laser safety and became IEC-compliant.

Until recently, companies manufacturing laser products for sale in North America and Europe had to conduct different safety tests for each geographic location. However, the U.S. Center For Devices and Radiological Health (CDRH), a division of the Food and Drug Administration, issued Laser Notice Number 50 in July 2001. This notice indicates that CDRH will accept compliance with portions of IEC 60825-1 as an alternative to meeting certain requirements published by CDRH itself, mainly with regard to labeling. The result: Europe and North America have an agreed-upon set of labeling requirements applicable to both markets. These common standards will undoubtedly help to remove technical barriers resulting from differing certification criteria in Europe and the U.S.

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IGMP

Internet Group Management Protocol is defined in RFC 1112 as the standard for IP multicasting in the Internet. It's used to establish host memberships in particular multicast groups on a single network. The mechanisms of the protocol allow a host to inform its local router, using Host Membership Reports, that it wants to receive messages addressed to a specific multicast group. All hosts conforming to level 2 of the IP multicasting specification require IGMP.

IP

Abbreviation of Internet Protocol, pronounced as two separate letters. IP specifies the format of packets, also called datagrams, and the addressing scheme. Most networks combine IP with a higher-level protocol called Transport Control Protocol (TCP), which establishes a virtual connection between a destination and a source. IP by itself is something like the postal system. It allows you to address a package and drop it in the system, but there's no direct link between you and the recipient. TCP/IP, on the other hand, establishes a connection between two hosts so that they can send messages back and forth for a period of time. The current version of IP is IPv4. A new version, called IPv6 or IPng, is under development.

ISDN

Abbreviation of Integrated Services Digital Network, an international communications standard for sending voice, video, and data over digital telephone lines or normal telephone wires. ISDN supports data transfer rates of 64 Kbps (64,000 bits per second). Most ISDN lines offered by telephone companies provide two lines at once, called B channels. One line can be used for voice and the other for data. Both lines can be used for data to reach data rates of 128 Kbps, more than twice the speed of today's fastest modems. The original version of ISDN employs baseband transmission. Another version, called B-ISDN, uses broadband transmission and is able to support transmission rates of 1.5 Mbps. B-ISDN requires fiber optic cables and is not widely available

MPLS

Multiprotocol Label Switching is an IETF initiative that integrates Layer 2 information about network links (bandwidth, latency, utilization) into Layer 3 (IP) within a particular autonomous system — or ISP in order to simplify and improve IP-packet exchange. MPLS gives network operators flexibility to divert and route traffic around link failures, congestion, and bottlenecks.

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OC

Short for Optical Carrier, used to specify the speed of fiber optic networks conforming to the SONET standard. The table shows the speeds for common OC levels.

OC-1 = 51.85 Mbps OC-3 = 155.52 Mbps OC-12 = 622.08 Mbps OC-24 = 1.244 Gbps OC-48 = 2.488 Gbps

OSI Model

Short for Open System Interconnection, an ISO standard for worldwide communications that defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.

Layer Name Function 7 Application Layer Program-to-program communication. 6 Presentation Layer Manages data representation conversions. For example, the Presentation Layer would be responsible for converting from EBCDIC to ASCII. 5 Session Layer Responsible for establishing and maintaining communications channels. In practice, this layer is often combined with the Transport Layer. 4 Transport Layer Responsible for end-to-end integrity of data transmission. 3 Network Layer Routes data from one node to another. 2 Data Link Layer Responsible for physical passing data from one node to another. 1 Physical Layer Manages putting data onto the network media and taking the data off.

Packet Switching

Refers to protocols in which messages are divided into packets before they are sent. Each packet is then transmitted individually and can even follow different routes to its destination. Once all the packets forming a message arrive at the destination, they are recompiled into the original message. Most modern Wide Area Network (WAN) protocols, including TCP/IP, X.25, and Frame Relay, are based on packet-switching technologies. In contrast, normal telephone service is based on a circuit-switching technology, in which a dedicated line is allocated for transmission between two parties. Circuit-switching is ideal when data must be transmitted quickly and must arrive in the same order in which it's sent. This is the case with most real-time data, such as live audio and video. Packet switching is more efficient and robust for data that can withstand some delays in transmission, such as e-mail messages and Web pages. A new technology, ATM, attempts to combine the best of both worlds — the guaranteed delivery of circuit-switched networks and the robustness and efficiency of packet-switching networks.

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PON

Passive Optical Network is a high bandwidth point to multipoint optical fiber network based on the asynchronous transfer mode protocol (ATM). PONs generally consist of an OLT (Optical Line Termination), which is connected to ONUs (Optical Network Units), using only fiber cables, optical splitters and other passive components (do not transmit signals using electricity). Up to 32 ONUs can be connected to an OLT. The OLT is located at a local exchange, and the ONU is located either on the street, in a building, or even in a user's home. PONs rely on lightwaves for data transfer. In a PON, signals are routed over the local link with all signals along that link going to all interim transfer points. Optical splitters route signals through the network; optical receivers at intermediate points and subscriber terminals tuned for specific wavelengths of light direct signals intended for their groups of subscribers. At the final destination, a specific residence or business can detect its specified signal. PONs are capable of delivering high volumes of upstream and downstream bandwidth (up to 622 Mbps downstream and 155 Mbps upstream), which can be changed on-the-fly depending on an individual user's needs.

Router

A device that connects any number of LANs. Routers use headers and a forwarding table to determine where packets go, and they use ICMP to communicate with each other and configure the best route between any two hosts.

SDH

Short for Synchronous Digital Hierarchy, an international standard for synchronous data transmission over fiber optic cables. The North American equivalent of SDH is SONET.

• Single Mode Fiber
  Yellow and labeled
  62.5/125 Core and Cladding
• Multi-Mode
  Orange and Gray exterior
• ST Fiber connecter that is like a BNC bayonette connection
• SC This is the fiber type connector that is push-pull connectors

SONET

Short for Synchronous Optical Network, a standard for connecting fiber-optic transmission systems. SONET was proposed by Bellcore in the middle 1980s and is now an ANSI standard. SONET defines interface standards at the physical layer of the OSI seven-layer model. The standard defines a hierarchy of interface rates that allow data streams at different rates to be multiplexed. SONET establishes Optical Carrier (OC) levels from 51.8 Mbps (about the same as a T-3 line) to 2.48 Gbps. Prior rate standards used by different countries specified rates that were not compatible for multiplexing. With the implementation of SONET, communication carriers throughout the world can interconnect their existing digital carrier and fiber optic systems. The international equivalent of SONET, standardized by the ITU, is called SDH. SDH defines a standard rate of transmission at 155.52 Mbps, which is referred to as STS-3 at the electrical level and STM-1 for SDH. STM-1 is equivalent to SONET's Optical Carrier (OC) levels -3.

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Switch

In networks, a device that filters and forwards packets between LAN segments. Switches operate at the data link layer (layer 2) of the OSI Reference Model and therefore support any packet protocol. LANs that use switches to join segments are called switched LANs or, in the case of Ethernet networks, switched Ethernet LANs.

TCP/IP

Abbreviation for Transmission Control Protocol/Internet Protocol, the suite of communications protocols used to connect hosts on the Internet. TCP/IP uses several protocols, the two main ones being TCP and IP. TCP/IP is built into the UNIX operating system and is used by the Internet, making it the de facto standard for transmitting data over networks. Even network operating systems that have their own protocols, such as Netware, also support TCP/IP.

UTP

Short for Unshielded Twisted Pair, a popular type of cable that consists of two unshielded wires twisted around each other. Due to its low cost, UTP cabling is used extensively for local-area networks (LANs) and telephone connections. UTP cabling does not offer as high bandwidth or as good protection from interference as coaxial or fiber optic cables, but it is less expensive and easier to work with.

VCSEL Lasers

Vertical-cavity surface emitting lasers. Of the two types of diode lasers, the vertical-cavity surface emitting lasers (VCSELs) have advantages over the traditionally used edge-emitting lasers. The laser beam from a VCSEL is circularly symmetric and hence can be very tightly focused, in contrast with the highly asymmetric output beam of an edge-emitting laser. The tighter focusing makes a VCSEL easier to couple to an optical fiber. VCSELs can also be produced in two-dimensional arrays, which cannot be achieved using the edge-emitting lasers. Fabricating VSCELs in a two-dimensional array would allow for the possibility of parallel or phased transmission.

VLAN

Short for virtual LAN, a network of computers that behave as if they are connected to the same wire even though they may actually be physically located on different segments of a LAN. VLANs are configured through software rather than hardware, which makes them extremely flexible. One of the biggest advantages of VLANs is that when a computer is physically moved to another location, it can stay on the same VLAN without any hardware reconfiguration.

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VPN

Short for Virtual Private Network, a network that is constructed by using public wires to connect nodes. For example, there are a number of systems that enable you to create networks using the Internet as the medium for transporting data. These systems use encryption and other security mechanisms to ensure that only authorized users can access the network and that the data cannot be intercepted.

WDM

Wavelength Division Multiplexing, a type of multiplexing developed for use on optical fiber. WDM modulates each of several data streams onto a different part of the light spectrum. WDM is the optical equivalent of FDM. Also see DWDM.

100BASE-T

A networking standard that supports data transfer rates up to 100 Mbps (100 megabits per second). 100BASE-T is based on the older Ethernet standard. Because it is 10 times faster than Ethernet, it is often referred to as Fast Ethernet. Officially, the 100BASE-T standard is IEEE 802.3u.

Like Ethernet, 100BASE-T is based on the CSMA/CD LAN access method. There are several different cabling schemes that can be used with 100BASE-T, including:

• 100BASE-TX: two pairs of high-quality twisted-pair wires
• 100BASE-T4: four pairs of normal-quality twisted-pair wires
• 100BASE-FX: fiber optic cables. All Ethernet interfaces are multi-mode fiber and use 1300nm
• 10BASE-FX is 850nm