Editing Datastream

{{about|the UK-specific technology|the more general meaning of the term |Data stream}}
{{abbreviations|date=November 2011}}

'''Datastream''' is a type of [[broadband network]] connection in the United Kingdom. Datastream is a wholesale product in which the wholesale customer can purchase connectivity between their own point of presence and a number of end users. Some authors use the term "datastream" for replacing the term [[dataflow]] to avoid confusion with dataflow computing or [[dataflow architecture]], based on an indeterministic machine paradigm (a research scene which is dead meanwhile).

== Technical details ==
The connections between the end users and the [[Other Logical Operator]] (OLO) (the wholesale customer of the DataStream product) were provided in three parts.

# BT provided connectivity between the end user and the nearest BT Serving Exchange via [[asymmetric digital subscriber line]], [[symmetric digital subscriber line]], and [[fiber to the x|fibre to the x]]. The end user access line could have a bandwidth ranging between 288&nbsp;kbit/s and 8,128&nbsp;kbit/s (8&nbsp;Mibit/s) downstream and up to 832&nbsp;kbit/s upstream for Asymmetric digital subscriber line, and up to 2048&nbsp;kbit/s (2&nbsp;Mibit/s) for Symmetric digital subscriber line. For fibre-based connections, speeds can be as high as 100&nbsp;Mbit/s although most connections of this type are fibre from exchange to cabinet so therefore limited to a maximum of 40&nbsp;Mbit/s. 
# For each serving exchange involved in providing end user access lines, a virtual path is provisioned to a BT ATM switch on BT's core network. A virtual path can range in size from 250&nbsp;kbit/s to 34&nbsp;Mbit/s. One or more [[Digital Subscriber Line Digital Multiplexer]]s at the serving exchange combine the traffic from the end user access lines for delivery to the ATM switch.
# From the BT switch, the traffic from the various virtual paths is combined and an ATM Customer Access Link (CAL) is used to connect to the [[Network Terminating Equipment]] (NTE) at the wholesale customer's point of presence.

== Comparison to IPStream and LLU ==
[[IPstream]], DataStream, and [[local loop unbundling]] (LLU) are all products that can be used for the delivery of bit-stream products, but represent different degrees of involvement from BT. In the case of LLU, the OLO has direct access to the twisted pair delivered to the end-user's [[Network termination|NTE]] and has near total control of the connection from end-to-end. With DataStream, BT still manages the [[DSL]] multiplexing equipment at the various local exchanges, and hands off the aggregated traffic to the OLO at one or a few points of presence. With IPStream, BT also provides the IP transport services

==External links==
* [http://www.thinkbroadband.com/news/i/1061.html Technical Information] on Datastream from thinkbroadband.com
* [http://www2.bt.com/static/i/btretail/panretail/terms/bt374.htm Conditions for BT Datastream Service] from BT

[[Category:Digital subscriber line]]
[[Category:Telecommunications in the United Kingdom]]


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