What is Trunking?
Trunking is a method of carrying traffic of VLANs over a point-to-point link between two devices. If two switches are connected together, switches’ ports of both sides of the link must be configured for trunking. The ports on both the switches of the link must also be configured with the same tagging mechanism that can be InterSwitch Link (ISL) or 802.1Q.
Trunking is a method that is common to most forms of electronic communications today. Essentially, trunking makes it possible for a communications system such as a telephone network to provide widespread access to many different users. This function is achieved by the ability to allow users to share a particular set of lines or frequencies, rather than requiring one single line or trunk for each user. The end result of this process of sharing frequencies means faster and more stable connectivity for a larger client base. Trunking has made many of the telecommunications services many of us rely on daily to be possible. For example, the PBX system that many offices use to receive and route inbound calls is made possible by trunking technology. The inbound call enters the PBX on what is known as a trunk line. The trunk call is received by a line is provided by the local telephone access provider. Once the signal is received, the PBX can route the call to any extension currently active on
“Trunking” is a word borrowed from the telephone system to describe a large number of users sharing a much smaller number of communication paths. The wires from your home telephone, along with hundreds of others, connect to a local “central office.” Your central office connects with other central offices around the country by way of “trunks,” which are really just pairs of copper wires (or these days, strands of glass called fiber optics). When you pick up the phone and place a long distance call, your central office assigns one of its idle trunks to your call, linking you to the destination central office. That trunk remains dedicated to you for as long as your call lasts. When you finally hang up, the trunk returns to idle and is available for another call. Because your phone sits idle most of the time (unless you have teen-aged children), just like all the other telephones in your neighborhood, the telephone company doesn’t have to go to the expense of having a trunk between central
Traditional radio equipment works because all parties involved in the communication agree on what frequencies they will utilize. Traditional radio scanners work by scanning for and then listening to those frequencies. Trunking radios, on the other hand, constantly renegotiate the frequencies utilized for the conversation. This allows for more efficient utilization of limited frequencies because each conversation does not require a dedicated channel. However, it also makes it very difficult to scan trunked conversations because you do not usually know what frequency the next portion of the conversation will appear on. Trunked radio systems are utilize one or more “Control” or “Data” channels. The data passed via the control channel instructs each radio in the system which frequency to switch to in order to remain on the selected channel. Several utilities are available to monitor and decode some of the common trunking protocols: Trunking Protocol Trunking Software Motorola Trunker, Trep
The simplest explanation: Trunking dynamically assigns pooled frequencies within the electromagnetic spectrum, on an as-needed basis. Assignment of a frequency, or channel, is done via some form of digital signaling. LTR, SmarTrunk, EDACS, MARC-V, MPT, TETRA, iDEN, and traditional Motorola trunking are examples of the types of trunking currently available. Heres an example of Trunking using a real life experience: Say you need to go to the bank to visit a teller. The bank has fifteen teller windows but this time of the day the traffic is slow so some windows are open, and available for any entering customer, and some busy. As a customer enters the bank he or she simply proceeds to an open window and begins their transaction. Now the day grows later and traffic begins to pick up. Numerous customers enter the bank at a pace quicker than any transaction between a customer and teller so a line, or queue, is created. This type of queue basically works on the principle of first come, first s
