This is about the network-design strategies; for riding in auto cargo space, see Trunking (auto). Trunking is the act of riding in an Automobile in the trunk rather than in designated passenger positions

Trunking is a concept in modern communications by which a communications system can provide network access to many clients by sharing a set of lines or frequencies instead of providing them individually. This is analogous to the structure of a tree with one trunk and many branches. Examples of this include telephone systems and the VHF radios commonly used by police agencies. More recently port trunking has been applied in computer networking as well. Link aggregation, or IEEE 8023ad, is a Computer networking term which describes using multiple Ethernet network cables/ports in parallel to increase the

Contents 1 Etymology 2 Radio Communication 3 Telecommunications 3.1 Trunk line 3.2 Trunk call 3.3 Telephone exchange 4 Computer networks 4.1 Link Aggregation 4.2 VLANs 5 See also 6 References

Etymology

How the term came to apply to communications is unclear, but it probably derives from transport. In the middle 19th century the principal road of India was named Grand Trunk Road. The Grand Trunk Road (commonly abbreviated to GT Road is one of South Asia 's oldest and longest major roads The Grand Trunk Railway in Canada was named in 1852, long before any telephone cable. The Grand Trunk Railway (GTR was a railway system which operated in the Canadian provinces of Quebec and Ontario, as well as the American Since telephone trunks, trunk railways, and trunk roads connect branch offices or branch roads, they act much like the trunk of a tree. A trunk road, trunk highway, or strategic road is a major Road &mdashusually connecting two or more cities, Ports Airports A private branch exchange (PBX is a Telephone exchange that serves a particular business or office as opposed to one that a Common carrier or telephone company In Botany, trunk (or bole) refers to the main structural member of a Tree that supports the Branches and is supported by and directly attached A tree is a perennial Woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or

An alternative explanation is that, from an early stage in the development of telephony, the need was found for thick cables (up to around 10 cm diameter) containing many pairs of wires. These were usually covered in lead. Thus, both in colour and size they resembled an elephant's trunk. Elephants ( family: Elephantidae) are large land Mammals of the order Proboscidea. This leaves open the question of what term was applied to connections among exchanges during the years when only open wire was used. In the field of Telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls

Radio Communication

In radio communication (public safety, etc. ), trunking refers to the ability of a signal to hop frequencies. Initially, all communication is received at known frequencies, but as silence is detected the site controller will broadcast new frequencies on which to communicate via a control channel, and the entire group of listening units will simultaneously migrate to that next frequency. ^[1][2]

Telecommunications

In telecommunications, a trunk is one of^[3]:

• In a communications network, a single transmission channel between two points, which are the switching centers or nodes or both. A telecommunications network is a network of Telecommunications links and nodes arranged so that messages may be passed from one part of the network to another over In Telecommunications transmission is the process of sending propagating and receiving an analogue or digital information signal over a physical point-to-point or Channel, in communications (sometimes called communications channel) refers to the medium used to convey Information from a A switching center is a node in a Telecommunications Circuit switching network which is connected to either another switching center and/or to end user See Trunked radio system. trunked radio system is a complex type of computer-controlled radio system
• A circuit between telephone switchboards or other switching equipment, as distinguished from local loop circuits which extend from telephone exchange switching equipment to individual telephones or information origination/termination equipment. An electrical network is an interconnection of Electrical elements such as Resistors Inductors Capacitors Transmission lines Voltage A switchboard (also called a manual exchange) was a device used to connect a group of Telephones manually to one another or to an outside connection within and between In Telephony, the local loop (also referred to as a subscriber line) is the physical link or circuit that connects from the Demarcation point of the In the field of Telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls Basic principle A traditional landline telephone system also known as "plain old telephone service" (POTS, commonly handles both signaling and audio information

Trunk line

When dealing with a PBX, trunk lines are the phone lines coming into the PBX from the telephone provider ^[4]. This differentiates these incoming lines from extension lines that connect the PBX to (usually) individual phone sets. An extension telephone is an additional Telephone wired to the same Telephone line as another Trunking saves cost, because there are usually fewer trunk lines than extension lines, since it is unusual in most offices to have all extension lines in use for external calls at once. Trunk lines transmit voice and data in formats such as analog, T1, E1, ISDN or PRI. The primary rate interface (PRI is a Telecommunications standard for carrying multiple DS0 voice and data transmissions between two physical locations See illustration here The dial tone lines for outgoing calls are called DDCO (Direct Dial Central Office) trunks. A dial tone (known in the British Isles as a dialling tone) is a Telephony signal used to indicate that the Telephone exchange is working

Trunk call

In the UK and the Commonwealth countries, a trunk call was a long distance one as opposed to a local call. Long distance in Telecommunications, refers to Telephone calls made outside a certain area usually characterized by an Area code outside of a Local In Telephony, the term local call has the following meanings Any call using a single switching facility; that is not traveling to another See Subscriber trunk dialling and Trunk vs Toll. Subscriber trunk dialling ( STD, also known as subscriber toll dialling) is a term for the UK Telephone system allowing subscribers to dial trunk In the US, under the purview of the Bell System, local Telephone calls were free except in a few big cities and the term toll was adopted for Long

Telephone exchange

Trunking also refers to the connection of switches and circuits within a telephone exchange. A switch is a mechanical device used to connect and disconnect an electric Circuit at will A telecommunication circuit is defined as follows The complete path between two terminals over which one-way or two-way communications may be provided In the field of Telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls ^[5] Trunking is closely related to the concept of Grading. In Telecommunication engineering and in particular Teletraffic engineering, the quality of voice service is specified by two measures the grade of service ( Trunking allows a group of inlet switches at the same time. An inlet is a narrow body of water between islands or leading inland from a larger body of water often leading to an enclosed body of water such as a sound, bay, Thus the service provider can provide a lesser number of circuits than might otherwise be required, allowing many users to "share" a smaller number of connections and achieve capacity savings. A service provider is an Entity that provides services to other entities ^[6][7]

Computer networks

Link Aggregation

Main article: Link aggregation

In computer networking, trunking refers to the use of multiple network cables or ports in parallel to increase the link speed beyond the limits of any one single cable or port. Link aggregation, or IEEE 8023ad, is a Computer networking term which describes using multiple Ethernet network cables/ports in parallel to increase the Computer networking is the Engineering Discipline concerned with communication between Computer systems or devices Networking routers The Physical Layer is the first level in the seven-layer OSI model of computer networking. In Computer hardware, a 'port' serves as an interface between the computer and other computers or peripheral devices This is called port trunking or link aggregation. Link aggregation, or IEEE 8023ad, is a Computer networking term which describes using multiple Ethernet network cables/ports in parallel to increase the Link aggregation, or IEEE 8023ad, is a Computer networking term which describes using multiple Ethernet network cables/ports in parallel to increase the Trunks may be used to interconnect switches, such as major, minor, public and private switches, to form networks.

VLANs

In the context of VLANs, Cisco uses the term "trunking" to denote a network link carrying multiple VLANs between 2 switches or between a switch and a router, through the use of a "trunking protocol. A virtual LAN, commonly known as a VLAN, is a group of hosts with a common set of requirements that communicate as if they were attached to the Broadcast domain " To allow for multiple VLANs on one link, frames from individual VLANs must be identified. The most common and preferred method, IEEE 802.1Q adds a tag to the Ethernet frame header, labeling it as belonging to a certain VLAN; Since 802. IEEE 8021Q (also known as VLAN Tagging was a project in the IEEE 802 standards process to develop a mechanism to allow multiple bridged networks to transparently Ethernet is a family of frame -based Computer networking technologies for Local area networks (LANs 1Q is a non-proprietary standard, it is the only option in an environment with multiple vendor equipment. Cisco also has a proprietary trunking protocol called Inter Switch Link which encapsulates the Ethernet frame with its own container, which labels the frame as belonging to a specific VLAN. Cisco Inter-Switch Link ( ISL) is a Cisco Systems proprietary protocol that maintains VLAN information as traffic flows between switches and routers

See also

• Multi-Link Trunking (MLT): Nortel's Port Aggregation Protocol
• Split multi-link trunking (SMLT): Nortel's proprietary enhancement to LACP

References

1. ^ http://www.tech-faq.com/trunking.shtml (aeolianmeson)
2. ^ http://www.police-scanner.info/scanning/trunked-radio-systems.htm (aeolianmeson)
3. ^ From the Federal Standard 1037C and from MIL-STD-188 and from the Code of Federal Regulations, Telecommunications Parts 0-199
4. ^ Versadial, Call recording encyclopedia, last accessed 18 Apr 2007
5. ^ Flood, J. See also Nortel List of Nortel Products and Protocols Nortel Networks Corporation () formerly known as Northern Telecom Limited and sometimes known simply as Nortel, is a multinational Telecommunications SMLT Topologies two switches between which the SMLT is split are known as aggregation switches and form a logical cluster which appears to the other end of the SMLT link as a single SMLT Topologies two switches between which the SMLT is split are known as aggregation switches and form a logical cluster which appears to the other end of the SMLT link as a single Nortel Networks Corporation () formerly known as Northern Telecom Limited and sometimes known simply as Nortel, is a multinational Telecommunications Federal Standard 1037C, entitled Telecommunications Glossary of Telecommunication Terms is a United States Federal Standard issued by the General Services Administration MIL-STD-188 is a series of US military standards relating to Telecommunications Purpose Faced with “past technical deficiencies in telecommunications The Code of Federal Regulations Telecommunications, containing the U E. , Telecommunications Switching, Traffic and Networks Chapter 4: Telecommunications Traffic. New York: Prentice-Hall, 1998.
6. ^ Motorola, Trunking Communications Overview, last accessed 13 February 2005.
7. ^ The Genesis Group, Trunking Basics, last accessed 13 February 2005.

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