Trunking

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Contents 1 Computer networks 1.1 Port trunking 1.2 VLANs 2 Telecommunications 2.1 Trunk call 2.2 Telephone exchange 2.3 Derivation 3 References

[edit] Computer networks

[edit] Port trunking

In computer networking, trunking describes using multiple network cables or ports in parallel to increase the link speed beyond the limits of any one single cable or port. This is called port trunking or link aggregation. Trunks may be used to interconnect switches, such as major, minor, public and private switches, to form networks.

[edit] VLANs

In the context of VLANs, the term "trunk" denotes a network link carrying multiple VLANs which are identified by labels (or "tags") inserted into their packets. Trunking protocols like ISL and IEEE 802.1Q are needed to carry the data through the trunk.

[edit] Telecommunications

In telecommunications, a trunk is one of^[1]:

• In a communications network, a single transmission channel between two points, which are the switching centers or nodes or both. See Trunked Radio Systems.
• A circuit between switchboards or other switching equipment, as distinguished from circuits which extend between telephone exchange switching equipment and information origination/termination equipment.

[edit] Trunk call

In the UK and the Commonwealth countries, a trunk call was a long distance one as opposed to a local call. See Subscriber trunk dialling and Trunk vs Toll.

[edit] Telephone exchange

Trunking also refers to the connection of switches and circuits within a telephone exchange.^[2] Trunking is closely related to the concept of Grading. Trunking allows a group of inlet switches at the same time. 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.^[3][4]

[edit] Derivation

From an early stage in the development of telephony, the need was found for thick cables (up to around 10 cm diameter). These were usually covered in lead. Thus, both in colour and size they resembled an elephant's trunk. Also, since they connect branch offices they act much like the trunk of a tree.

[edit] References

1. ^ From the Federal Standard 1037C and from MIL-STD-188 and from the Code of Federal Regulations, Telecommunications Parts 0-199
2. ^ Flood, J.E., Telecommunications Switching, Traffic and Networks Chapter 4: Telecommunications Traffic. New York: Prentice-Hall, 1998.
3. ^ Motorola, Trunking Communications Overview, last accessed 13 February 2005.
4. ^ The Genesis Group, Trunking Basics, last accessed 13 February 2005.