Bundling (data transmission)

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Bundling (English trunking ) in telecommunications and computer science refers to the merging of several transmission channels (physical lines, frequency bands, etc.) to form a single logical connection that is visible to the user.

In computer science, trunking usually refers to the merging of several physically separate Ethernet or telecommunications connections into a single logical one. The data is transferred with synchronous or asynchronous methods over the resulting logical connection. At the physical level, either a single channel or (to distribute the load and increase throughput) several parallel channels are used. The Link Aggregation Control Protocol (LACP) used for bandwidth scaling is standardized by the IEEE under "Aggregation of Multiple Link Segments"; see also the term Spanning Tree Protocol .

Trunking is also used as a term for trunked radio networks.

Trunking is a term from Sun Microsystems , but it is also used across manufacturers. For Cisco , the term Etherchannel in Linux systems, the term bonding used actually is in all three at the same function.

The term “trunk” is used in VLANs with a slightly different meaning. Several different VLANs are routed over a physical connection, so there is no increase in throughput.

Trunk in the network cabling

In structured cabling , considered here within a data center , trunks are the combination of several cables in a single one. In addition to simplifying a physical installation, this bundling offers other advantages. This makes it easier to handle changes, cable routes in the data center are better used and, last but not least, fire loads are reduced.

A distinction is made here between copper trunks and fiber optic trunks. Copper trunks are typically formed from six to eight individual cables that are cut to length at the factory and terminated on both sides with modular RJ45 connection units. Fiber optic trunks can be designed as single fiber trunks , for example, factory - made with LC connectors at both ends , or as multi-fiber trunks. The latter has a multi-fiber connector such as the MPO connector at its ends and can typically be used for parallel optical systems such as Infiniband or 40/100 Gigabit Ethernet, depending on the design.

To migrate from single-fiber technology (based on e.g. LC or SC connectors) to parallel optical transmission, module technology is used in addition to the MPO trunks. This includes an MPO with z. B. twelve fibers and the front six LC duplex couplings or dividers (harnesses) with z. B. one side twelve MPO fibers. Six LC duplex connectors are used on the other side.

Bundling in communications technology

In communications engineering, a bundle is a logical group of channels (or lines) that are used equally from the user's point of view. Telecommunications systems differentiate between feeder, recipient and internal bundles. The distribution of traffic to the various channels of a customer group is not transparent for the user. Since bundles cannot be tailored to every conceivable offer for economic reasons , a suitable traffic model in connection with a certain service must ensure that blockages in a bundle do not exceed an acceptable level. The dimensioning of bundles is carried out using methods of traffic theory .

literature

  • Volker Jung, Hans-Jürgen Warnecke (Hrsg.): Handbook for telecommunications. 2nd edition, Springer Verlag Berlin Heidelberg, Berlin Heidelberg 2002, ISBN 978-3-642-62736-1 .
  • Peter Bocker: data transfer. Volume I - Basics, Springer Verlag Berlin Heidelberg GmbH, Berlin Heidelberg 1976, ISBN 978-3-662-06499-3 .

See also

Web links