The Telecommunications Management Network (TMN) model was introduced by ITU-T Recommendation M.3000 in 1985 as a reference model for the Operation Support System (OSS) of telecommunications service providers. The TMN concept is an architectural framework for the interconnection of different types of OSS components and network elements. TMN also describes the standardized interfaces and protocols used for the exchange of information between OSS components and network elements, and the total functionality needed for network management.
The TMN model composes of the following four layers:
* Business management layer: performs functions related to business aspects, analyzes trends and quality issues, for example, or to provide a basis for billing and other financial reports.
* Service management layer: performs functions for the handling of services in the network: definition, administration and charging of services
* Network management layer: performs functions for distribution of network resources: configuration, control and supervision of the network
* Element management layer: contains functions for the handling of individual network elements. This includes alarm management, handling of information, backup, logging, and maintenance of hardware
At each layer in the TMN model, five functional areas called FCAPS are defined:
* Fault management: Fault recognition, isolation, reporting and recording.
* Accounting management: Collection, buffering and delivery of payment and accounting information.
* Configuration management: Installation of network equipment, setting of states and parameters, configuration of network capacity.
* Performance management: Collection, buffering and delivery of operating statistics for network optimization and capacity planning.
* Security management: Administration of authorization functions; handling of simultaneous use of an OSS, protection against intrusion from un-authorized users.
The above five functional areas form the basis of all network management systems for both data or tele-communications. The mapping between the TMN and FCAPS is shown below:
FCAPS Fault Configuration Accounting Performance Security
TMN
Business Management No No Yes Yes Yes
Service Management Yes Yes Yes Yes Yes
Network Management Yes Yes No Yes Yes
Element Management Yes Yes No Yes Yes
The TeleManagement Forum is working on a newer model to replace the aging TMN. This new model is called TOM (Telecoms Operations Map) or eTOM (enhanced Telecom Operations Map).
Mapping between TMN reference model and the FCAPS:
Mapping between TMN reference model and the FCAPS:
Mapping between TMN reference model and the FCAPS
Related Terms: TMN, Telecom Management Network, Operation Support System, OSS, FCAPS, TOM, eTOM
Network Protocol Suite Directory Index
Network communication is defined by network protocols. A network protocol is a formal set of rules, conventions and data structure that governs how computers exchange information over a network. In other words, network protocol is a standard procedure and format that two data communication devices must understand, accept and use to be able to talk to each other.
Network protocols are defined by many standard organizations worldwide and technology vendors over years of technology evolution and developments. In the following directory, we organize the network protocols according to their key functions, or their origin/sponsors - we call it protocol family and protocol suite. One of the most famous network protocol family is TCP/IP suite, which is the technical foundation of the Internet.
AppleTalk: Apple Computer Protocols Suite
AppleTalk is a multi-layered protocol of Apple Computers providing internetwork routing, transaction and data stream service, naming service, and comprehensive file and print sharing among Apple systems using the LocalTalk interface built into the Appl hardware. AppleTalk ports to other network media such as Ethernet by the use of LocalTalk to Ethernet bridges or by Ethernet add-in boards for Apple machines. Many third-party applications exist for the AppleTalk protocols.
An AppleTalk network can support up to 32 devices and data can be exchanged at a speed of 230.4 kilobits per second (Kbps). Devices can be as much as 1,000 feet apart. At the physical level, AppleTalk is a network with a bus topology that uses a trunk cable between connection modules.
The LocalTalk Link Access Protocol (LLAP) must be common to all systems on the network bus and handles the node-to-node delivery of data between devices connected to a single AppleTalk network. Data link layer interfaces to Ethernet, Token ring and FDDI are defined.
The Datagram Delivery Protocol (DDP) is the AppleTalk protocol implemented at the network layer. DDP is a connectionless datagram protocol providing best-effort delivery, which is similar to IP in the TCP/IP suite.
At the Transport Layer, several protocols exist to add different types of functionality to the underlying services. The Routing Table Maintenance Protocol (RTMP) allows bridges and internet routers to dynamically discover routes to the different AppleTalk networks in an internet. The AppleTalk Transaction Protocol (ATP) is responsible for controlling the transactions between requestor and responder sockets.
The Name Binding Protocol (NBP) is for the translation of a character string name into the internet address of the corresponding client. The AppleTalk Echo Protocol (AEP) allows a node to send data to any other node on an AppleTalk internet and receive an echoed copy of that data in return. The AppleTalk Data Stream Protocol (ADSP) is designed to provide byte-stream data transmission in a full duplex mode between any two sockets on an AppleTalk internet. The Zone Information Protocol (ZIP) is used to maintain an internet-wide mapping of networks to zone names.
In the Session Layer, the AppleTalk Session Protocol (ASP) is designed to interact with AppleTalk Transaction Protocol (ATP) to provide for establishing, maintaining and closing sessions.
The AppleTalk Filing Protocol (AFP) is an application or presentation layer protocol designed to control access to remote file systems. A key application using this protocol is the AppleShare for file sharing among a variety of user computers.
Protocol Structure
AppleTalk protocols in the OSI layers:
Ethernet: IEEE 802.3 Local Area Network (LAN) protocols
Ethernet protocols refer to the family of local-area network (LAN) covered by the IEEE 802.3. In the Ethernet standard, there are two modes of operation: half-duplex and full-duplex modes. In the half duplex mode, data are transmitted using the popular Carrier-Sense Multiple Access/Collision Detection (CSMA/CD) protocol on a shared medium. The main disadvantages of the half-duplex are the efficiency and distance limitation, in which the link distance is limited by the minimum MAC frame size. This restriction reduces the efficiency drastically for high-rate transmission. Therefore, the carrier extension technique is used to ensure the minimum frame size of 512 bytes in Gigabit Ethernet to achieve a reasonable link distance.
Four data rates are currently defined for operation over optical fiber and twisted-pair cables:
* 10 Mbps—10Base-T Ethernet (IEEE 802.3)
* 100 Mbps—Fast Ethernet (IEEE 802.3u)
* 1000 Mbps—Gigabit Ethernet (IEEE 802.3z)
* 10-Gigabit - 10 Gbps Ethernet (IEEE 802.3ae).
In this document, we discuss the general aspects of the Ethernet. The specific issues regarding Fast Ethernet, Gigabit and 10 Gigabit Ethernet will be discussed in separate documents.
The Ethernet system consists of three basic elements: 1. the physical medium used to carry Ethernet signals between computers, 2. a set of medium access control rules embedded in each Ethernet interface that allow multiple computers to fairly arbitrate access to the shared Ethernet channel, and 3. an Ethernet frame that consists of a standardized set of bits used to carry data over the system.
As with all IEEE 802 protocols, the ISO data link layer is divided into two IEEE 802 sublayers, the Media Access Control (MAC) sublayer and the MAC-client sublayer. The IEEE 802.3 physical layer corresponds to the ISO physical layer.
The MAC sub-layer has two primary responsibilities:
* Data encapsulation, including frame assembly before transmission, and frame parsing/error detection during and after reception
* Media access control, including initiation of frame transmission and recovery from transmission failure
The MAC-client sub-layer may be one of the following:
* Logical Link Control (LLC), which provides the interface between the Ethernet MAC and the upper layers in the protocol stack of the end station. The LLC sublayer is defined by IEEE 802.2 standards.
* Bridge entity, which provides LAN-to-LAN interfaces between LANs that use the same protocol (for example, Ethernet to Ethernet) and also between different protocols (for example, Ethernet to Token Ring). Bridge entities are defined by IEEE 802.1 standards
Each Ethernet-equipped computer operates independently of all other stations on the network: there is no central controller. All stations attached to an Ethernet are connected to a shared signaling system, also called the medium. To send data a station first listens to the channel, and when the channel is idle the station transmits its data in the form of an Ethernet frame, or packet.
After each frame transmission, all stations on the network must contend equally for the next frame transmission opportunity. Access to the shared channel is determined by the medium access control (MAC) mechanism embedded in the Ethernet interface located in each station. The medium access control mechanism is based on a system called Carrier Sense Multiple Access with Collision Detection (CSMA/CD).
As each Ethernet frame is sent onto the shared signal channel, all Ethernet interfaces look at the destination address. If the destination address of the frame matches with the interface address, the frame will be read entirely and be delivered to the networking software running on that computer. All other network interfaces will stop reading the frame when they discover that the destination address does not match their own address.
When it comes to how signals flow over the set of media segments that make up an Ethernet system, it helps to understand the topology of the system. The signal topology of the Ethernet is also known as the logical topology, to distinguish it from the actual physical layout of the media cables. The logical topology of an Ethernet provides a single channel (or bus) that carries Ethernet signals to all stations.
Multiple Ethernet segments can be linked together to form a larger Ethernet LAN using a signal amplifying and retiming device called a repeater. Through the use of repeaters, a given Ethernet system of multiple segments can grow as a "non-rooted branching tree." “Non-rooted" means that the resulting system of linked segments may grow in any direction, and does not have a specific root segment. Most importantly, segments must never be connected in a loop. Every segment in the system must have two ends, since the Ethernet system will not operate correctly in the presence of loop paths.
Even though the media segments may be physically connected in a star pattern, with multiple segments attached to a repeater, the logical topology is still that of a single Ethernet channel that carries signals to all stations.
Token Ring: IEEE 802.5 LAN Protocol
Token Ring is a LAN protocol defined in the IEEE 802.5 where all stations are connected in a ring and each station can directly hear transmissions only from its immediate neighbor. Permission to transmit is granted by a message (token) that circulates around the ring.
Token Ring as defined in IEEE 802.5 is originated from the IBM Token Ring LAN technologies. Both are based on the Token Passing technologies. While them differ in minor ways but generally compatible with each other.
Token-passing networks move a small frame, called a token, around the network. Possession of the token grants the right to transmit. If a node receiving the token has no information to send, it seizes the token, alters 1 bit of the token (which turns the token into a start-of-frame sequence), appends the information that it wants to transmit, and sends this information to the next station on the ring. While the information frame is circling the ring, no token is on the network, which means that other stations wanting to transmit must wait. Therefore, collisions cannot occur in Token Ring networks.
The information frame circulates the ring until it reaches the intended destination station, which copies the information for further processing. The information frame continues to circle the ring and is finally removed when it reaches the sending station. The sending station can check the returning frame to see whether the frame was seen and subsequently copied by the destination.
Unlike Ethernet CSMA/CD networks, token-passing networks are deterministic, which means that it is possible to calculate the maximum time that will pass before any end station will be capable of transmitting. This feature and several reliability features make Token Ring networks ideal for applications in which delay must be predictable and robust network operation is important.
The Fiber Distributed-Data Interface (FDDI) also uses the Token Passing protocol.
Protocol Structure - Token Ring: IEEE 802.5 LAN Protocol
1 byte 2 bytes 3 bytes 9 bytes 15 bytes
SDEL AC FC Destination address Source address
Route information 0-30 bytes
Information (LLC or MAC) variable
FCS (4 bytes) EDEL (1) FS(1)
* SDEL / EDEL - Starting Delimiter / Ending Delimiter. Both the SDEL and EDEL have intentional Manchester code violations in certain bit positions so that the start and end of a frame can never be accidentally recognized in the middle of other data.
* AC - Access control field Contains the Priority fields.
* FC - Frame control field indicates whether the frame contains data or control information
* Destination address C Destination station address.
* Source address CSource station address.
* Route information C The field with routing control, route descriptor and routing type information.
* Information - The Information field may be LLC or MAC.
* FCS - Frame check sequence.
* Frame status - Contains bits that may be set on by the recipient of the frame to signal recognition of the address and whether the frame was successfully copied.
FDDI: Fiber Distributed Data Interface
Fiber Distributed Data Interface (FDDI) is a set of ANSI protocols for sending digital data over fiber optic cable. FDDI networks are token-passing (similar to IEEE 802.5 Token Ring protocol) and dual-ring networks, and support data rates of up to 100 Mbps. FDDI networks are typically used as backbones technology because of its support for high bandwidth and great distance. A related copper specification similar to FDDI protocols, called Copper Distributed Data Interface (CDDI), has also been defined to provide 100-Mbps service over twisted-pair copper.
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.
FDDI uses dual-ring architecture with traffic on each ring flowing in opposite directions (called counter-rotating). The dual rings consist of a primary and a secondary ring. During normal operation, the primary ring is used for data transmission, and the secondary ring remains idle. As will be discussed in detail later in this chapter, the primary purpose of the dual rings is to provide superior reliability and robustness.
FDDI specifies the physical and media-access portions of the OSI reference model. FDDI is not actually a single specification, but it is a collection of four separate specifications, each with a specific function. Combined, these specifications have the capability to provide high-speed connectivity between upper-layer protocols such as TCP/IP and IPX, and media such as fiber-optic cabling.
FDDI"s four specifications are the Media Access Control (MAC), Physical Layer Protocol (PHY), Physical-Medium Dependent (PMD), and Station Management (SMT) specifications. The MAC specification defines how the medium is accessed, including frame format, token handling, addressing, algorithms for calculating cyclic redundancy check (CRC) value, and error-recovery mechanisms. The PHY specification defines data encoding/decoding procedures, clocking requirements, and framing, among other functions. The PMD specification defines the characteristics of the transmission medium, including fiber-optic links, power levels, bit-error rates, optical components, and connectors. The SMT specification defines FDDI station configuration, ring configuration, and ring control features, including station insertion and removal, initialization, fault isolation and recovery, scheduling, and statistics collection.
Protocol Structure - FDDI: Fiber Distributed Data Interface
2 6 6
0-30
Variable 4 bytes
Frame control Destination address Source address Route information Information FCS
Frame control - The frame control structure is as follows:
C L F F Z Z Z Z
C Class bit: 0 Asynchronous frame; 1 Synchronous frame/
L Address length bit: 0 16 bits (never); 1 48 bits (always).
FF Format bits.
ZZZZ Control bits.
Destination address - The address structure is as follows:
I/G U/L Address bits
Source address - The address structure is as follows:
I/G RII Address bits
I/G Individual/group address: 0 Group address; 1 Individual address.
RII Routing information indicator: 0 RI absent; 1 RI present.
Route Information - The structure of the route information is as follows:
3 5 1 6 1 16 16 16
RT LTH D LF r RD1 RD@ ... RDn
RC Routing control (16 bits).
RDn Route descriptor (16 bits).
RT Routing type (3 bits).
LTH Length (5 bits).
D Direction bit (1 bit).
LF Largest frame (6 bits).
r reserved (1 bit).
Information - The Information field may be LLC, MAC or SMT protocol.
FCS - Frame check sequence.
Related protocols:IEEE 802.5, 802.2
